Dr. Jeff Masters' WunderBlog

Pakistan monsoon floods kill at least 800

By: JeffMasters, 05:56 PM GMT am 31. Juli 2010

The deadliest weather disaster of 2010 is unfolding in Pakistan, where heavy monsoon rains have triggered flooding that has left at least 817 people dead. A death toll may reach 3000, according to the local head of Pakistan's largest rescue service, and more monsoon rains are on the way. Monsoon floods have also hit southeastern Afghanistan hard, where at least 64 have been killed. The heavy rains were caused by a monsoon depression (also called a monsoon low) that formed over the Bay of Bengal on July 24, crossed over India, and reached Pakistan on July 27. The rains increased in intensity over the next two days, peaking on July 29 and 30, when a low pressure system that moved across Pakistan from the west enhanced rainfall from the monsoon depression. Over the 3-day period July 28 - 30, torrential rains in excess of 8 inches (203 mm) fell in many regions of northwest Pakistan, resulting in that nation's worst floods since at least 1929. Rainfall amounts at two stations in the catchment basins of the Jhelum River and Indus River reached 19.49" (495 mm) for the month of July, and 7.56" (192 mm) fell in a single day, July 30, at Tarbela.

A monsoon depression is similar to a tropical depression, but forms in the Indian Southwest Monsoon over the Bay of Bengal. Like tropical depressions, monsoon depressions are hundreds of miles in diameter, have nearly calm winds near the center, and can have sustained winds of 30 - 35 mph. Four monsoon depressions originated in the Bay of Bengal in 2009; the average is 6 - 7. A new monsoon depression developed over the Bay of Bengal yesterday, and is headed westward towards Pakistan. Heavy rains from this new monsoon depression will begin affecting Pakistan on Monday, according to the Pakistan Meteorological Department.


Figure 1. The heavy thunderstorms of a monsoon depression lie over northwestern Pakistan near Islamabad in this visible satellite image taken by NASA's MODIS instrument on July 29, 2010. Image credit: NASA.

Tropical Atlantic may get active by mid-week
The Invest 90L tropical wave off the coast of Africa has grown disorganized, and NHC is no longer generating forecast tracks for the system. A tropical wave that moved of the coast of Africa Thursday is in the eastern Atlantic near 10N 25W, a few hundred miles south of the Cape Verdes Islands. This morning's 12Z run of the NOGAPS model predicts that this wave will develop into a tropical storm by Wednesday, and reach the Lesser Antilles Islands Friday. This morning's 12Z run of the GFS and ECMWF models predict that an area of disturbed weather near 8N 37W, in the east-central Atlantic, will develop into a tropical storm that will move through the Lesser Antilles on Thursday. Wind shear is low to moderate, sea surface temperatures are at record highs, and the dust and dry air of the Saharan Air Layer (SAL) are far enough to the north of these disturbed areas to potentially allow formation of a tropical storm. However, the Madden-Julian Oscillation currently favors downward motion over the tropical Atlantic, which will act to decrease the chances of tropical storm formation. NHC is giving a 30% chance that a tropical depression will form by Monday afternoon from one of these areas of disturbed weather.

Next update
I'll have an update Monday morning at the latest.

Jeff Masters

Flood

Updated: 07:13 PM GMT am 31. Juli 2010

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Little change to 90L; new African tropical wave is worth watching

By: JeffMasters, 08:53 PM GMT am 30. Juli 2010

Invest 90L is a tropical wave in the eastern Atlantic near 10N 33W with a very limited amount of heavy thunderstorm activity but a decent amount of spin. It does not have a well-defined surface circulation, and has shown little change in organization today. CIMMS wind-shear analyses show a low amount of wind shear (5 - 10 knots) over 90L, and sea surface temperatures are a record warm 29°C. The wave currently is in a moist environment and is not being affected by the dry Saharan Air Layer (SAL) to its northwest. The disturbance has moved far enough away from the Equator to leverage the Earth's spin to help it develop. The Saharan Air Layer with its dust and dry air lurks just to the north of 90L, but the SHIPS model predicts 90L will remain far enough from the dry air over the next five days so that it will not interfere with development.


Figure 1. Afternoon visible satellite image from 2pm EDT 7/30/10 of the relatively tiny 90L, and the large new tropical wave that moved off the coast of Africa yesterday.

Forecast for 90L
One factor inhibiting development of 90L this week will be the Madden-Julian Oscillation (MJO.) The MJO currently favors downward motion over the tropical Atlantic, which will act to decrease the chances of tropical storm formation. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased.

Perhaps the main factor interfering with 90L's development will be the presence of the large tropical wave to the east of 90L that moved off the coast of Africa yesterday. This new wave is large enough and close enough to 90L that it will probably begin to dominate regional weather patterns this weekend, stealing away 90L's inflow of low-level moist air. The new wave may also act to bring sinking air over 90L that will tend to suppress 90L's thunderstorm activity. It may turn out that the new wave will also steal some of 90L's spin, and end up being a threat to develop itself later on this weekend.

The latest 8am EDT (12Z) model runs for 90L show very little in the way of development of the storm. The predominant track forecast takes 90L into or just north of the northern Lesser Antilles Islands about 6 - 8 days from now. Looking at climatology based on research done by Dr. Bob Hart at Florida State University,, 90L has a 19% chance of developing into a tropical cyclone by 2pm Sunday. NHC is putting these odds at 20%. Dr. Hart also has an experimental product showing that historically, about 30% of all tropical cyclones that develop at 90L's current position eventually hit land as a hurricane. Of course, 90L is not yet a tropical cyclone, and I think that the large tropical wave off the coast of Africa will kill 90L this weekend.

Tropical wave in the eastern Caribbean
A tropical wave in the eastern Caribbean, south of the Dominican Republic, is moving west at 15 - 20 mph with no signs of development. The wave is under a high 20 knots of wind shear, due to strong upper-level westerly winds from an upper level low centered north of Puerto Rico. This shear is expected to remain remain high through Saturday. By Sunday, when the wave will be approaching Nicaragua, the wave will be far enough away from the upper level low that shear should fall to the moderate range, 10 - 20 knots. Some development is possible on Sunday, but the wave will have only about a 1-day window to develop before its westerly motion brings it inland over Nicaragua on Monday. NHC is giving this wave a 10% chance of developing into a tropical depression by 2pm Sunday.

Extreme cold records for 2010
In my post yesterday, I reported that fourteen countries had set their all-time hottest temperature record this year. I neglected to mention that one country has also set its coldest temperature in recorded history mark in 2010. Guinea had its coldest temperature in its history on January 9, 2010, when the mercury hit 1.4°C (34.5°F) at Mali-ville in the Labe region. Of the 229 countries with extreme coldest temperature records, 14 of these records have occurred in the past ten years (6% of all countries). There have been five times as many (74) extreme hottest temperature records in the past ten years (33% of all countries.) My source for extreme weather records is Chris Burt, author of Extreme Weather.

New study finds huge drop in the plants that form the base of the oceanic food chain
A study published this week in the journal Nature documents that microscopic marine phytoplankton, which form the basis of the marine food chain, have declined by 40% globally since 1950. Joe Romm at climateprogress.org discusses the implications, using this headline:

Scientists may have found the most devastating impact yet of human-caused global warming — a 40% decline in phytoplankton since 1950 linked to the rise in ocean sea surface temperatures. If confirmed, it may represent the single most important finding of the year in climate science.

I plan to discuss this paper next week.

Next update
I'll have an update this weekend, probably by 8pm EDT Saturday.

Jeff Masters

Hurricane

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Moscow hits 102°F; hottest day ever in Finland; 90L a long-range theat

By: JeffMasters, 01:54 AM GMT am 30. Juli 2010

At 4pm local time today in Moscow, Russia, the temperature surpassed 100°F for the first time in recorded history. The high temperature of 100.8°F (37.8°C) recorded at the Moscow Observatory, the official weather location for Moscow, beat Moscow's previous record of 99.5°F (37.5°C), set just three days ago, on July 26. Prior to 2010, Moscow's hottest temperature of all-time was 36.6°C (98.2°F), set in August, 1920. Records in Moscow go back to 1879. Baltschug, another official downtown Moscow weather site, hit an astonishing 102.2°F (39.0°C) today. Finland also recorded its hottest temperature in its history today, when the mercury hit 99°F (37.2°C) at Joensuu. The old (undisputed) record was 95°F (35°C) at Jvaskyla on July 9, 1914. There is little relief in sight, as the latest forecast for Moscow predicts continued highs in the 90s for most of the coming week.

A remarkable year for extreme heat
Finland's new national heat record makes it the fourteenth country (or semi-independent territory) to break an all-time hottest temperature record this year. My source for extreme temperature records is Chris Burt, author of the book Extreme Weather. July in Moscow is easily going to smash the record for hottest month in Moscow's history. By my rough estimate, the temperature has been 18°F (10°C) above average this month. The record hottest July, in 1938, had temperatures 5.3°C above average. Given that the planet as a whole has seen record high temperatures the past four months in a row, it should not be a surprise to see unprecedented heat waves like the Russian heat wave. A record warm planet "loads the dice" in favor of regional heat waves more extreme than anything experienced in recorded history.


Figure 1. Russia's heat wave has contributed to a severe fire season this July. Fires on dry peat bogs east of Moscow are covering the city with smoke as this photo taken yesterday (July 28, 2010.) Tiny red dots indicate hot spots of high surface temperatures associated with fires, and multiple clusters of such dots appear east of Moscow. Dull gray smoke mixes with opaque white clouds east and northeast of the capital city. Air pollution levels in Moscow due to the smoke and smog are so high that residents have been warned to stay home rather than go in to work. Firefighters are battling 340 blazes across Russia covering 86,658 hectares (214,136 acres) amid a drought that led the government to declare weather-related emergencies in 23 crop-producing regions. Agriculture Minister Yelena Skrynnik said on July 23 that the drought had damaged 10.1 million hectares, or 32 percent of all land under cultivation, according to Bloomberg. Raging fires have destroyed hundreds of houses across Russia today and forced mass evacuations in the city of Voronezh, 300 miles southeast of Moscow, according to the Associated Press. Image credit: NASA's Aqua satellite.

Fourteen extreme national high temperature records have been set in 2010
This year now ranks in second place for the most number of countries that have set extreme heat records, according to a list supplied to me today by Chris Burt. The new list removes a number of old disputed records, resulting in the year 2007 surpassing 2010 as the year with the most extreme heat records--fifteen. Keep in mind that the matter of determining extreme records is very difficult, and it is often a judgment call as to whether an old record is reliable or not. The list of countries (225) includes islands that are not independent countries, such as Puerto Rico and Greenland. One-third (33%) of those heat records were set in the past ten years. Ten years have had extreme heat records set at five or more countries on Mr. Burt's list:

2007: 15 records
2010: 14 records
2003: 12 records
2005: 11 records
1998: 9 records
1983: 9 records
2009: 6 records
2000: 5 records
1999: 5 records
1987: 5 records

I highly recommend the book Extreme Weather by Chris Burt for those interested in weather records. I thank Mr. Burt and weather record researchers Maximiliano Herrera and Howard Rainford for their assistance identifying this year's new extreme temperature records. Here's a list of the fourteen nations that have set extreme heat records this year:

Finland recorded its hottest temperature on July 29, 2010, when the mercury hit 99°F (37.2°C) at Joensuu. The old (undisputed) record was 95°F (35°C) at Jvaskyla on July 9, 1914.

Qatar had its hottest temperature in history on July 14, 2010, when the mercury hit 50.4°C (122.7°F) at Doha Airport.

Russia had its hottest temperature in history on July 11, when the mercury rose to 44.0°C (111.2°F) in Yashkul, Kalmykia Republic, in the European portion of Russia near the Kazakhstan border. The previous hottest temperature in Russia (not including the former Soviet republics) was the 43.8°C (110.8°F) reading measured at Alexander Gaj, Kalmykia Republic, on August 6, 1940. The remarkable heat in Russia this year has not been limited just to the European portion of the country--the Asian portion of Russia also recorded its hottest temperature in history this year, a 42.3°C (108.1°F) reading at Belogorsk, near the Amur River border with China. The previous record for the Asian portion of Russia was 41.7°C (107.1°F) at nearby Aksha on July 21, 2004.

Sudan recorded its hottest temperature in its history on June 25 when the mercury rose to 49.6°C (121.3°F) at Dongola. The previous record was 49.5°C (121.1°F) set in July 1987 in Aba Hamed.

Niger tied its record for hottest day in history on June 22, 2010, when the temperature reached 47.1°C (116.8°F) at Bilma. That record stood for just one day, as Bilma broke the record again on June 23, when the mercury topped out at 48.2°C (118.8°F). The previous record was 47.1°C on May 24, 1998, also at Bilma.

Saudi Arabia had its hottest temperature ever on June 22, 2010, with a reading of 52.0°C (125.6°F) in Jeddah, the second largest city in Saudi Arabia. The previous record was 51.7°C (125.1°F), at Abqaiq, date unknown. The record heat was accompanied by a sandstorm, which caused eight power plants to go offline, resulting in blackouts to several Saudi cities.

Chad had its hottest day in history on June 22, 2010, when the temperature reached 47.6°C (117.7°F) at Faya. The previous record was 47.4°C (117.3°F) at Faya on June 3 and June 9, 1961.

Kuwait recorded its hottest temperature in history on June 15 in Abdaly, according to the Kuwait Met office. The mercury hit 52.6°C (126.7°F). Kuwait's previous all-time hottest temperature was 51.9°C (125.4°F), on July 27,2007, at Abdaly. Temperatures reached 51°C (123.8°F) in the capital of Kuwait City on June 15, 2010.

Iraq had its hottest day in history on June 14, 2010, when the mercury hit 52.0°C (125.6°F) in Basra. Iraq's previous record was 51.7°C (125.1°F) set August 8, 1937, in Ash Shu'aybah.

Pakistan had its hottest temperature in history on May 26, when the mercury hit an astonishing 53.5°C (128.3°F) at the town of MohenjuDaro, according to the Pakistani Meteorological Department. While this temperature reading must be reviewed by the World Meteorological Organization (WMO) for authenticity, not only is the 128.3°F reading the hottest temperature ever recorded in Pakistan, it is the hottest reliably measured temperature ever recorded on the continent of Asia.

Myanmar (Burma) had its hottest temperature in its recorded history on May 12, when the mercury hit 47°C (116.6°F) in Myinmu, according to the Myanmar Department of Meteorology and Hydrology. Myanmar's previous hottest temperature was 45.8°C (114.4°F) at Minbu, Magwe division on May 9, 1998. According to Chris Burt, author of the authoritative weather records book Extreme Weather, the 47°C measured this year is the hottest temperature in Southeast Asia history.

Ascention Island (St. Helena, a U.K. Territory) had its hottest temperature in history on March 25, 2010, when the mercury hit 34.9°C (94.8°C) at Georgetown. The previous record was 34.0°C (93.2°F) at Georgetown in April 2003, exact day unknown.

The Solomon Islands had their hottest temperature in history on February 1, 2010, when the mercury hit 36.1°C (97°F) at Lata Nendo (Ndeni). The previous record for Solomon Islands was 35.6°C (96.0°F) at Honaiara, date unknown.

Columbia had its hottest temperature in history on January 24, 2010, when Puerto Salgar hit 42.3°C (108°F). The previous record was 42.0°C (107.6°F) at El Salto in March 1988 (exact day unknown).

90L forms in far eastern Atlantic
NHC has designated an area of thunderstorms in the tropical Atlantic as Invest 90L (8.5 N, 30.0 W). Microwave remote sensing suggests there are some decent thunderstorms in 90L, as peak rain rates were around 1 - 2 inches per hour. According to CIMMS wind-shear analyses, 90L is under a moderate 10 - 15 knots of wind shear, and upper level winds over the disturbance are diverging, which creates a vacuum effect that will enhance updrafts and thunderstorm growth. The disturbance is tracking into a broad area of weak shear to the west and northwest. The steering currents for 90L are to the west-northwest, which will move it into this area of weaker shear. The disturbance is at 8°N latitude, which is too close to the Equator to leverage the Earth's spin very well to spin up. As 90L's west-northwest motion carries it farther from the Equator, the additional spin the disturbance gains from the Earth's rotation will aid development, particularly once 90L gets north of 10°N latitude.The Saharan Air Layer with its dust and dry air lurks just to the north of 90L, but the SHIPS model predicts 90L will remain far enough from the dry air over the next five days so that it will not interfere with development.


Figure 2. IR Satellite Composite of 90L taken at 5:40 pm EDT.


Figure 3. Saharan Air Layer analysis courtesy of the University of Wisconsin CIMSS group.

Model Forecasts and Climatology
The latest 2pm EDT (18Z) runs of the GFDL and HWRF models show 90L developing into a hurricane 3 - 5 days from now. These models suggest that 90L will pass well northeast of the Lesser Antilles Islands. The 18Z GFS model develops 90L into a tropical storm about 7 days from now, and forecasts a track through the northern Lesser Antilles Islands 7 - 8 days from now. The 18Z NOGAPS and 12Z ECMWF models show little development of 90L. The GFDL and HWRF models are too aggressive developing 90L, and likely show too much of a northward motion due to excessive depth of the system they portray. The GFS solution, showing a more delayed development and possible threat to the Lesser Antilles Islands is probably more reasonable. Looking at climatology based on research done by Dr. Bob Hart at Florida State University,, 90L has a 36% chance of developing into a tropical cyclone by 2pm Saturday. NHC is putting these odds at 20%. Dr. Hart also has an experimental product showing that historically, about 30% of all tropical cyclones at 90L's current position eventually hit land as a hurricane. Of course, 90L is not yet a tropical cyclone, but these odds suggest that 90L has the potential to become a dangerous Cape Verdes-type hurricane that will affect land.

Next update
I'll have an update by 8pm Friday.

Jeff Masters (with lots of help from Rob Carver on the 90L portion of the post!)

Heat

Updated: 02:03 AM GMT am 30. Juli 2010

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Invest 90L in the Tropical Atlantic

By: JeffMasters, 11:35 PM GMT am 29. Juli 2010

Hi everybody, Dr. Rob Carver filling in for Dr. Masters while he's on vacation.

NHC has designated an area of thunderstorms in the tropical Atlantic as Invest 90L (8.5 N, 30.0 W). Microwave remote sensing suggests there are some decent storms in 90L, peak rain rates were around 1-2 inches/hours. According to CIMMS wind-shear analyses 90L is under 10-15 knots of shear with positive divergence aloft. The former isn't quite favorable for further development as it will ventilate the system, but the latter is favorable because it will aid in removing outflow from the storms. There's also a broad area of weak shear to the west and northwest of 90L's current position. Looking at the 500 mb height patterns, the steering currents for 90L are to the WNW, which will move it into the area of weaker shear and get it further away from the equator. This is important because if 90L stays south, it will have trouble developing a circulation. It will have a better chance of becoming a tropical cyclone once it goes north of 10N. The Saharan Air Layer is lurking just to the north of 90L. A WNW track would keep 90L out of the SAL, which is good for development.


Fig. 1 IR Satellite Composite of 90L taken at 540 PM EDT.


Fig. 2 Saharan Air Layer analysis courtesy of CIMMS.

Model Forecasts and Climatology
The 12Z Canadian model moves 90L to the WNW and develops tropical-storm force winds at the surface. The 12Z and 18Z GFS runs are less aggressive in intensifying 90L and adjusts the track so that 90L is moving to the WNW. Based on the run-to-run consistency, previous model verification (i.e. the Canadian model's tendency to overdo intensification), general synoptic pattern, I favor the GFS solution for now. Looking at climatology based on research done by Dr. Bob Hart at Florida State University, none of the tropical cyclones that passed within 1 degree of 90L's current position has ever made landfall. We'll have to keep an eye on this storm, but I don't think it's likely to be a major threat to the Caribbean or US.

Update
Dr. Masters says he'll update this blog entry with a discussion of the Moscow heatwaves later tonight.

Hurricane

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Storms of My Grandchildren by Dr. James Hansen

By: JeffMasters, 11:34 PM GMT am 26. Juli 2010

"Storms of My Grandchildren: The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity" is NASA climate change scientist Dr. James Hansen's first book. Dr. Hansen is arguably the most visible and well-respected climate change scientist in the world, and has headed the NASA Goddard Institute for Space Studies in New York City since 1981. He is also an adjunct professor in the Department of Earth and Environmental Sciences at Columbia University. Dr. Hansen greatly raised awareness of the threat of global warming during his Congressional testimony during the record hot summer of 1988, and issued one of the first-ever climate model predictions of global warming (see an analysis here to see how his 1988 prediction did.) In 2009, Dr. Hansen was awarded the Carl-Gustaf Rossby Research Medal, the highest honor bestowed by the American Meteorological Society, for his "outstanding contributions to climate modeling, understanding climate change forcings and sensitivity, and for clear communication of climate science in the public arena."

Storms of My Grandchildren focuses on the key concepts of the science of climate change, told through Hansen's personal experiences as a key player in field's scientific advancements and political dramas over the past 40 years. Dr. Hansen's writing style is very straight-forward and understandable, and he clearly explains the scientific concepts involved in a friendly way that anyone with a high school level science education can understand. I did not find any scientific errors in his book. However, some of his explanations are too long-winded, and the book is probably too long, at 274 pages. Nevertheless, Storms of My Grandchildren is a must-read, due to the importance of the subject matter and who is writing it. Hansen is not a fancy writer. He comes across as a plain Iowan who happened to stumble into the field of climate change and discovered things he had to speak out about. And he does plenty of speaking out in his book.

James Hansen vs. Richard Lindzen
Dr. Hansen's book opens with an interesting chapter on his participation in four meetings of Vice President Dick Cheney's cabinet-level Climate Task Force in 2001. It seems that the Bush Administration was prepared to let Dr. Hansen's views on climate change influence policy. However, Dr. Richard Lindzen, whom Hansen describes as "the dean of of global warming contrarians", was also present at the meetings. Dr.Lindzen was able to confuse the task force members enough so that they never took Dr. Hansen's views seriously. Hansen observes that "U.S. policies regarding carbon dioxide during the Bush-Cheney administration seem to have been based on, or at a minimum, congruent with, Lindzen's perspective." Hansen asserts that Lindzen was able to do this by acting more like a lawyer than a scientist: "He and other contrarians tend to act like lawyers defending a client, presenting only arguments that favor their client. This is in direct contradiction to...the scientific method." Hansen also comments that he asked Lindzen what he thought of the link between smoking and cancer, since Lindzen had been a witness for the tobacco industry decades earlier. Lindzen "began rattling off all the problems with the data relating smoking to health problems, which was closely analogous to his views of climate data."

Alarmism
Global warming contrarians often dismiss scientists such a Dr. Hansen as "alarmists" who concoct fearsome stories about climate change in order to get research funding. Dr. Lindzen made this accusation at Cheney's Climate Task Force in 2001. However, Dr. Hansen notes that "in 1981 I lost funding for research on the climate effects of carbon dioxide because the Energy Department was displeased with a paper, 'Climate Impact of Increasing Carbon Dioxide,' I had published in Science magazine. The paper made a number of predictions for the 21st century, including 'opening of the fabled Northwest Passage', which the Energy Department considered to be alarmist but which have since proven to be accurate." If you read Dr. Hansen's book and listen to his lectures, it is clear that he is not an alarmist out to get more research funding by hyping the dangers of global warming. Hansen says in his book that "my basic nature nature is very placid, even comfortably stolid", and that nature comes through very clearly in Storms of My Grandchildren. Hansen's writings express a quiet determination to plainly set forth the scientific truth on climate change. He has surprisingly few angry words towards the politicians, lobbyists, and scientists intent on distorting the scientific truth.

The science of climate change
The bulk of Storms of My Grandchildren is devoted to explanations of the science of climate change. Hansen's greatest concern is disintegration of the gerat ice sheets in Greenland and West Antarctica causing sea level rise: "Once the ice sheets begin to rapidly disintegrate, sea level would be continuously changing for centuries. Coastal cities would become impractical to maintain." Hansen is concerned that evidence from past climate periods show that the massive ice sheets that cover Greenland and Antarctica can melt quickly, with large changes within a century. For example, sea level at the end of the most recent Ice Age, 13,000 - 14,000 years ago, rose at a rate of 3 - 5 meters (10 - 17 feet) per century for several centuries. Hansen is convinced that just a 1.7 -2°C warming, which would likely result if we stabilize CO2 at 450 ppm, would be a "disaster scenario" that would trigger rapid disintegration of the ice sheets and disastrous rises in sea level. Hansen advocates stabilizing CO2 at 350 ppm (we are currently at 390 ppm, with a rate of increase of 2 ppm per year.)

Another of Hansen's main concerns is the extinction of species. He notes that studies of more than 1,000 species of plants, animals, and insects have found an average migration rate towards the poles due to climate warming in the last half of the 20th century to be four miles per decade. "That is not fast enough. During the past thirty years the lines marking the regions in which a given average temperature prevails (isotherms) have been moving poleward at a rate of about thirty-five miles per decade. If greenhouse gases continue to increase at business-as-usual rates, then the rate of isotherm movement will double in this century to at least seventy miles per decade."

Hansen's other main concern is the release of large amounts of methane gas stored in sea-floor sediments in the form of methane hydrates. If ocean temperatures warm according to predictions, the higher temperatures at the sea floor may be enough to destabilize the methane hydrate sediments and release huge quantities of methane into the atmosphere. Methane is a greenhouse gas 20 - 25 times more potent than carbon dioxide.

Solutions to the climate change problem
Dr. Hansen is a controversial figure, since he has stepped outside his field of expertise and become an activist in promoting solutions to the climate change problem. He devotes a chapter called "An Honest, Effective Path" in the book to this. His main theme is that we need to tax fossil fuels using a "fee-and-dividend" approach. All of the tax money collected would be distributed uniformly to the public. This carbon tax would gradually rise, giving people time to adjust their lifestyle, choice of vehicle, home insulation, etc. Those who do better at reducing their fossil fuel use will receive more in the dividend than they will pay in the added costs of the products they buy. The approach is straightforward and does not require a large bureaucracy, but currently has little political support. Hansen is vehemently opposed to the approach that has the most political support, "Cap-and-trade": "Cap-and-trade is what governments and the people in alligator shoes (the lobbyists for special interests) are trying to foist on you. Whoops. As an objective scientist I should delete such personal opinions, to at least flag them. But I am sixty-eight years old, and I am fed up with the way things work in Washington." Hansen also promotes an overlooked type of nuclear power, "fast" reactors with liquid metal coolant that produce far less nuclear waste and are much more efficient than conventional nuclear reactors.

Quotes from the book
"Humanity treads today on a slippery slope. As we continue to pump greenhouse gases into the air, we move onto a steeper, even more slippery incline. We seem oblivious to the danger--unaware how close we may be to a situation in which a catastrophic slip becomes practically unavoidable, a slip where we suddenly lose all control and are pulled into a torrential stream that hurls us over a precipice to our demise."

"In order for a democracy to function well, the public needs to be honestly informed. But the undue influence of special interests and government greenwash pose formidable barriers to a well-informed public. Without a well-informed public, humanity itself and all species on the planet are threatened."

"Of course by 2005 I was well aware that the NASA Office of Public Affairs had become an office of propaganda. In 2004, I learned that NASA press releases related to global warming were sent to the White House, where they were edited to appear less serious or discarded entirely."

"If we let special interests rule, my grandchildren and yours will pay the price."

"The role of money in our capitals is the biggest problem for democracy and for the planet."

"The problem with asking people to pledge to reduce their fossil fuel use is that even if lots of people do, one effect is reduced demand for fossil fuel and thus a lower price--making it easier for someone else to burn...it is necessary for people to reduce their emissions, but it is not sufficient if the government does not adopt policies that cause much of the fossil fuels to be left in the ground permanently."

"I have argued that it is time to 'draw a line in the sand' and demand no new coal plants."

"The present situation is analogous to that faced by Lincoln with slavery and Churchill with Nazism--the time for compromises and appeasement is over."

"Humans are beginning to hammer the climate system with a forcing more than an order of magnitude more powerful than the forcings that nature employed."

"Once ice sheet disintegration begins in earnest, our grandchildren will live the rest of their lives in a chaotic transition period."

"After the ice is gone, would Earth proceed to the Venus syndrome, a runaway greenhouse effect that would destroy all life on the planet, perhaps permanently? While that is difficult to say based on present information, I've come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a dead certainty."

"One suggestion I have for now: Support Bill McKibben and his organization 350.org. It is the most effective and responsible leadership in the public struggle for climate justice."

Commentary
James Hansen understands the Earth's climate as well as any person alive, and his concern about where our climate is headed makes Storms of My Grandchildren a must-read for everyone who cares about the world their grandchildren will inherit. Storms of My Grandchildren retails for $16.50 at Amazon.com. Dr. Hansen's web site is http://www.columbia.edu/~jeh1/.

Jeff Masters

Book and Movie Reviews

Updated: 11:36 PM GMT am 26. Juli 2010

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Bonnie barely alive

By: JeffMasters, 12:58 PM GMT am 24. Juli 2010

Tropical Depression Bonnie is barely clinging to life. Wind shear of 25 knots and dry air from an upper-level low pressure system over the Gulf of Mexico are taking their toll on Bonnie, which is now just a swirl of low clouds accompanied by a small clump of heavy thunderstorms on the north side of the center of circulation. These thunderstorms are now visible on New Orleans long range radar, and will arrive in coastal Louisiana early this afternoon, well ahead of the center. The Hurricane Hunters are in Bonnie, and have found a much weaker storm with top winds of just 30 mph.


Figure 1. Morning satellite image of Tropical Depression Bonnie. At the time, Bonnie had sustained winds of 30 mph.

Forecast for Bonnie
The current NHC forecast for Bonnie looks good, with the storm making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days, including several high tide cycles. Bonnie will be lucky to be a tropical depression at landfall, and should only create a storm surge of 1 - 2 feet that will come at low tide. This will result in a storm tide level that will inundate land to at most one foot above ground level.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Elsewhere in the tropics
There are no other threat areas of concern today. The only model calling for possible tropical development in the next week is the NOGAPS model, which predicts a strong tropical disturbance could form off the coast of Nicaragua in the Southwest Caribbean about a week from now.

Next update
The next updates will be by wunderground meteorologists Rob Carver and Shaun Tanner. I'm taking advantage of a break in the tropical action to take a few days away. I'll be back blogging on Friday, at the latest.

Jeff Masters

Hurricane

Updated: 08:32 PM GMT am 03. Januar 2012

Permalink

Bonnie weakens to a tropical depression

By: JeffMasters, 08:40 PM GMT am 23. Juli 2010

Tropical Depression Bonnie is nearing the end of its traverse of South Florida, and passage over land has significantly disrupted the small storm. Satellite images show almost no heavy thunderstorms near Bonnie's center of circulation, and the center is now exposed to view. Radar-estimated rainfall from the Key West radar shows that Bonnie dumped very little rain on South Florida--maximum rainfall amounts from the storm were about four inches over a small region southwest of Miami. Water vapor satellite loops show that Bonnie is embedded in a large area of dry air, thanks to an upper level low to the west over the Gulf of Mexico. This low has brought an increasing amount of wind shear to Bonnie today, and shear has increased from 20 knots this morning to 25 knots this afternoon. Surface observations in South Florida currently don't show any tropical storm force winds. Bonnie's top winds today were at Fowey Rocks, which had sustained winds of 46 mph, gusting to 53 mph, at 10:45 am EDT.


Figure 1. Satellite image of Bonnie from NASA's MODIS instrument, taken at 17:10 UTC July 23, 2010. Image credit: NASA/.

Track Forecast for Bonnie
The latest set of model runs from 8am EDT (12Z) are very similar to the three previous sets of runs, and this degree of consistency gives me confidence that Bonnie will stay within the cone of uncertainty depicted on the track forecast images. The projected track will take Bonnie over the oil spill region, and the storm's strong east to southeasterly winds will begin to affect the oil slick on Saturday morning. Assuming Bonnie doesn't dissipate over the next day, the storm's winds, coupled with a likely storm surge of 2 - 4 feet, will drive oil into a substantial area of the Louisiana marshlands. However, the current NHC forecast has Bonnie making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days, including several high tide cycles. The latest oil trajectory forecasts from NOAA (Figure 2) predicts potential oil impacts along a 150-mile stretch of Louisiana coast on Sunday.


Figure 2. Oil Trajectory forecast for Sunday for the Deepwater Horizon oil spill. Image credit: NOAA.

Intensity Forecast for Bonnie
Bonnie has been disrupted by its passage over land, and it will take at least six hours for the storm to reorganize once it moves over the warm waters of the Gulf of Mexico tonight. This process will be hindered by the large upper-level low to its west. If the low remains in its present location, relative to Bonnie, it will bring high wind shear of about 20 - 30 knots to the storm. This will allow for only slow intensification, or may even destroy Bonnie. Bonnie is unlikely to intensify to more than a 50 mph tropical storm, and I give a 30% chance it will dissipate over the Gulf of Mexico before making landfall. The GFDL model predicts Bonnie could hit the Gulf Coast as a 50 mph tropical storm, but the other major models such as the HWRF, GFS, ECMWF, and NOGAPS show a much weaker storm. I don't give Bonnie any chance of becoming a hurricane. NHC is putting the odds of Bonnie being a hurricane at 2 pm Saturday at 4% (5pm advisory.)

If you are wondering about the specific probabilities of receiving tropical storm force winds at your location, I recommend the wind probability product from NHC. The latest probabilities of various locations getting tropical storm force winds, 39 mph or higher, from the 5pm EDT advisory:

Buras, LA 30%
New Orleans 28%
Mobile, AL 37%
Pensacola, FL 30%

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update Saturday morning.

Jeff Masters

Hurricane

Updated: 08:32 PM GMT am 03. Januar 2012

Permalink

Bonnie makes landfall in South Florida

By: JeffMasters, 02:05 PM GMT am 23. Juli 2010

Tropical Storm Bonnie is making landfall in South Florida south of Miami as a minimal tropical storm with 40 mph winds. Radar-estimated rainfall from the Miami radar shows that Bonnie is a relatively dry storm--maximum rainfall amounts from the storm have been just 2 - 3 inches over the waters to the east of Miami. Water vapor satellite loops show that Bonnie is embedded in a large area of dry air, thanks to an upper level low to the west over the Gulf of Mexico. Over the past twelve hours, Bonnie has sped up, and this has brought the storm closer to the upper level low. The upper level low is now bringing high levels of wind shear--about 20 knots--to the tropical storm. Satellite images of Bonnie show that the storm is being stretched into an oval shape by the strong steering flow, and this distortion is inhibiting intensification. Bonnie is a small storm, and is only affecting a limited area of South Florida with strong winds and heavy rain. Surface observations in the Bahamas and South Florida showed a number of stations with winds in the 30 - 46 mph range this morning, including Fowey Rocks, which had sustatined winds of 46 mph, gusting to 53 mph, at 10:45 am EDT.


Figure 1. Radar image of Bonnie at landfall from the Miami radar.

Track Forecast for Bonnie
Bonnie has sped up more than the models expected, but they are in pretty good agreement about a continued track to the west-northwest to northwest with a landfall between Louisiana and the Florida Panhandle. The latest set of model runs from 2am EDT (6Z) are very similar to the two previous sets of runs, and this degree of consistency gives me confidence that Bonnie will stay within the cone of uncertainty depicted on the track forecast images. The projected track will take Bonnie over the oil spill region, and the storm's strong east to southeasterly winds will begin to affect the oil slick on Saturday morning. These winds, coupled with a storm surge of 2 - 4 feet, will result in a substantial area of the Louisiana marshlands getting oiled. The latest oil trajectory forecasts from NOAA (Figure 2) predict potential oil impacts along a 150-mile stretch of Louisiana coast on Sunday. Given Bonnie's rapid forward speed, small size, and expected landfall intensity of 50 mph or less, oil impacts on the Louisiana coast will be similar to or less than what was experienced during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days.


Figure 2. Oil Trajectory forecast for Sunday for the Deepwater Horizon oil spill. Image credit: NOAA.

Intensity Forecast for Bonnie
The primary detriment to development of Bonnie will be the presence of the large upper-level low to its west. If the low remains in its present location, relative to Bonnie, it will bring high wind shear of about 20 knots to the storm. This will allow for only slow intensification, and Bonnie is unlikely to intensify to more than a 50 mph tropical storm. This is the solution of the major global models such as the GFDL, HWRF, GFS, ECMWF, and NOGAPS. However, if the upper-level low weakens or pulls away from Bonnie, less shear and dry air will affect the storm, potentially allowing Bonnie to intensify to a strong tropical storm with 60 - 65 mph winds. The more statistically based intensity models--SHIPS and LGEM--foresee this sort of scenario. I'll go with the lower intensity scenario, since Bonnie is such a small storm and will be more sensitive than usual to hostile wind shear and dry air. I give Bonnie a 10% chance of becoming a hurricane. NHC is putting the odds of Bonnie being a hurricane at 8 pm Saturday at 9% (11am advisory.)

If you are wondering about the specific probabilities of receiving tropical storm force winds at your location, I recommend the wind probability product from NHC. The latest probabilities of various locations getting tropical storm force winds, 39 mph or higher, from the 11am EDT advisory :

Buras, LA 41%
New Orleans 32%
Mobile, AL 37%
Pensacola, FL 31%

Moscow records its hottest temperature in history
The temperature in Moscow, Russia reached 37°C (98.6°F) today, the hottest temperature ever recorded in the city. According to Wikipedia, Moscow's previous highest temperature ever recorded was 36.8°C (98.2°F) in August 1920. With the wunderground.com forecast for Moscow calling for continued temperatures in the mid to upper nineties for the next week, Moscow should easily be able break its record for warmest July since record keeping began in 1879.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update this afternoon.

Jeff Masters

Hurricane

Updated: 08:32 PM GMT am 03. Januar 2012

Permalink

Tropical Storm Bonnie Makes Her Debut

By: JeffMasters, 04:32 AM GMT am 23. Juli 2010

Hi everybody, this is Dr. Rob Carver filling in for Jeff on the late shift.

Based on information from Hurricane Hunters, the National Hurricane Center upgraded TD Three to Tropical Storm Bonnie. As of the 11PM EDT advisory, Bonnie was at 23.4N, 76.5W which is 285 miles southeast of Miami, Florida. Bonnie has maximum winds of 40 mph, a minimum central pressure of 1007 mb, and is moving to the northwest at 14 mph. Bonnie will pass over the Everglades/Florida Keys Friday and cross into the Gulf of Mexico Friday night/early Saturday morning. Tropical storm warnings are in effect for both Florida coasts south of Lake Okeechobee to Key West.


Fig. 1 IR satellite image of Tropical Storm Bonnie at 1216AM EDT.

Threats
NHC is expecting 2-4 inches of rain over south Florida due to Bonnie and 3-5 inches over the Bahamas. They are forecasting a storm surge of 1-2 feet. Tropical storm force winds are expected in the Bahamas starting Thursday night, and they are forecast to arrive in southern Florida Friday morning.

Impacts and Emergency Preparedness
As of 1130PDT EDT, the Key West NWS office is indicating that there are no evacuation orders in effect or planned for Monroe County (the Keys). Small craft are being advised to stay in port and be well secured to their docks. Two shelters will be opened, Key West High School and Stanley Switlik Elementary School in Marathon.

Most of the ships at the Deepwater Horizon oil spill site and other skimming ships have been ordered to seek safe harbor. In the statement, Adm. Allen said ships that operate the ROVs will be the last out and the first back to keep the wellhead observations going as long as possible.

Forecast/Model Assessment
The track models and ensemble models show remarkably good agreement for Bonnie's path across south Florida and towards southeast Louisiana. The current intensity forecast calls for Bonnie to maintain strong tropical storm force winds (40-50 knots) until it makes landfall in Louisiana, with a 15% chance of becoming a hurricane before then. However, the global models (GFS, Canadian GEM, NOGAPS) and the hurricane dynamical models (GFDL, Navy GFDL, and HWRF) do not intensify Bonnie at all. The statistical models (SHIPS and LGEM) support the intensity forecast.

I'm inclined to take the predictions of global and dynamical models with a large grain of salt. When I reviewed the latest model runs (18Z and 12Z), it was apparent that none of the models had a good initialization of Bonnie's structure. Bonnie has a relatively small circulation, so it's easy for the models' initialization to act like there isn't much of a storm there. Without accurate starting conditions, any model will have trouble producing an accurate forecast. NHC has a good summary of the different forecast models they use.

Next Update
Jeff will have an update sometime Friday morning.

Hurricane

Permalink

TD 3 growing more organized

By: JeffMasters, 08:01 PM GMT am 22. Juli 2010

Tropical Depression Three is steadily organizing, and appears poised to become a much stronger storm than was forecast. Water vapor satellite loops show that the upper level low to the west of TD 3 that has been bringing high levels of wind shear to the storm is now moving faster to the west than predicted. This faster motion has resulted in a reduction in wind shear over TD 3, to a moderate 10 knots. Satellite images of TD 3 show that the storm is taking advantage of the lower shear by developing several low-level spiral bands to the north and east of the center. However, the center of circulation is still exposed to view, and dry air is still getting injected into the core of the storm from the southwest. The storm's heavy thunderstorms have not increased in intensity this afternoon, and the amount of heavy thunderstorm activity near the core of the storm is still limited. TD 3 will need to build more intense thunderstorms near its center before significant intensification can occur. TD 3 is a small storm, and surface observations in the Bahamas do not show the circulation very well. An outer rain band of TD 3 is now visible on Miami long-range radar, and a flood watch has been issued for all of South Florida. The Hurricane Hunters are in the storm at present, and have found top surface winds of 35 - 40 mph.


Figure 1. Afternoon satellite image of TD 3.

Track Forecast for TD 3
The storm is in a straightforward steering current environment, and TD 3 should progress steadily to the west-northwest through Sunday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 8am EDT (12Z) foresee a track more to the north than the previous set of model runs. This increases the threat to the oil spill region, and I give a 40% chance that the oil spill region will see tropical storm force winds of 39 mph or higher this weekend. Oil recovery and relief well drilling operations should cease. If TD 3 makes a direct hit on the oil spill region as a tropical storm with 50 - 60 mph winds, it will likely drive a storm surge of 3 - 6 feet with high waves on top into the Louisiana marshlands, fouling a large area with oil. Oil would also penetrate into Lake Pontchartrain, which lies just two feet above sea level. However, the wave action of the storm will dilute the oil to some degree, which may limit the damage to the marshlands.

If you are wondering about the specific probabilities of receiving tropical storm force winds at your location, I recommend the wind probability product from NHC. The latest 5 pm probabilities of various locations getting tropical storm force winds, 39 mph or higher:

Marathon 55%
Marco Island 43%
Miami 34%
New Orleans 33%
Galveston 13%

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. If the low remains in its present location, relative to TD 3, it will bring wind shear of about 10 knots to the storm. This will allow for steady intensification of perhaps 20 mph per day, and TD 3 could be a hurricane by Sunday at that pace. However, if the upper-level low slows down a bit, relative to TD 3, more shear and dry air will affect the storm, potentially weakening it. None of the computer models is calling for TD 3 to strengthen into a hurricane, but if the shear continues at 10 knots, I expect TD 3 will become a hurricane. My low-confidence intensity forecast gives TD 3 a 40% chance of becoming a hurricane. NHC is putting the odds of TD 3 being a hurricane at 2 pm Sunday at 15% with their 5pm advisory.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and probably does not have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update in the morning. ABC World News Tonight will probably show a sound bite I did for them today, on their 6:30pm broadcast.

Jeff Masters

Hurricane

Updated: 08:33 PM GMT am 03. Januar 2012

Permalink

Tropical Depression Three forms

By: JeffMasters, 03:42 PM GMT am 22. Juli 2010

Tropical Depression Three has formed over the Bahama Islands, and appears poised to become Tropical Storm Bonnie later today. Satellite images of TD 3 show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. The surface circulation center is exposed to view, thanks to strong upper-level winds out of the southwest that are creating about 20 knots of wind shear. This wind shear is due to the counter-clockwise circulation of air around a large upper-level low pressure system over Florida that is moving west at about the same speed TD 3 is. Water vapor satellite loops show a large area of dry air is associated with the upper-level low pressure system, and this dry air is hindering development of TD 3. The storm is attempting to wrap a curved band of clouds around its center, on its west side. If TD 3 is able to do this, the center will be protected from shear and dry air, and more significant strengthening can occur. Surface observations in the Bahamas and several nearby ships have shown top winds in TD 3 of up to 35 mph, so the storm is close to the 40 mph winds needed to be classified as a tropical storm.


Figure 1. Water vapor satellite image showing dry air (brown colors) associated with the upper-level low over Florida. Image credit: NOAA/NESDIS.

Track Forecast for TD 3
The storm is in a fairly straightforward steering current environment, and TD 3 should progress steadily to the west to west-northwest through Saturday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 2am EDT (6Z) had the advantage of having data from a flight of the NOAA jet last night, so we have higher confidence than usual in the track of TD 3 over the next two days. The location of TD 3's final landfall along the Gulf of Mexico coast has the usual uncertainties for 3 - 4 days, with the various models calling for landfall somewhere between the upper Texas coast and the Florida Panhandle coast. Given the uncertainties, the move halt operations in the Deepwater Horizon blowout recovery effort are probably wise.

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. As long as this low remains in its present location, relative to TD 3, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of TD 3 to no more than about 10 - 15 mph per day. If the upper-level low slow down a bit, relative to TD 3, more shear will affect the storm, potentially weakening it. Conversely, if the upper-level low picks up speed and pulls away from TD 3, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it would not take much of an additional separation between TD 3 and the upper level low to substantially reduce shear and allow TD 3 to intensify into a hurricane on Saturday. I put the odds of TD 3 making it to hurricane strength in the Gulf of Mexico at 20%.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and may barely have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update between 3 - 4 pm, when the Hurricane Hunters will be in the storm. I'll also speculate on the possible impact the storm will have on the oil spill region.

Jeff Masters

Hurricane

Permalink

Tropical depression forming over the Bahamas

By: JeffMasters, 01:29 PM GMT am 22. Juli 2010

A tropical wave (Invest 97L) over the eastern Bahama Islands has developed a closed circulation at the surface, and has become a tropical depression or tropical storm. Here is the text of the Special Tropical Weather Outlook from NHC at 8:25am EDT today:

Visible satellite images and observations from the Bahamas indicate that the area of low pressure in the southeastern Bahamas has become better organized and a closed circulation has formed. Advisories on a tropical depression or a tropical storm will be initiated at 11 am EDT...1500 UTC today. This advisory will likely include tropical storm watches and warnings for portions of the Bahamas and southern Florida.

Satellite images of 97L show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. Water vapor satellite loops show a large area of dry air lies to the west of 97L, over Florida. This dry air is associated with a large upper-level low pressure system that is moving west at about the same speed 97L is. The counter-clockwise flow of air around the upper low is bringing about 20 knots of wind shear to 97L. Surface observations in the Bahamas and several nearby ships have shown top winds in 97L of up to 35 mph, so the storm is close to the 40 mph winds needed to be classified as a tropical storm.


Figure 1. Water vapor satellite image showing dry air (brown colors) associated with the upper-level low over Florida. Image credit: NOAA/NESDIS.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west to west-northwest through Saturday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 2am EDT (6Z) had the advantage of having data from a flight of the NOAA jet last night, so we have higher confidence than usual in the track of 97L over the next two days. The location of 97L's final landfall along the Gulf of Mexico coast has the usual uncertainties for 3 - 4 days, with the various models calling for landfall somewhere between the upper Texas coast and the Florida Panhandle coast. Given the uncertainties, the move halt operations in the Deepwater Horizon blowout recovery effort are probably wise.

Intensity Forecast for 97L
The primary detriment to development of 97L for the next three days will be the presence of the large upper-level low to its west. As long as this low remains in its present location, relative to 97L, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of 97L to no more than about 10 - 20 mph per day. If the upper-level low picks up speed and pulls away from 97L, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it is possible. I put the odds of 97L making it to hurricane strength in the Gulf of Mexico at 20%.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and may barely have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

I'll have an update after NHC releases their 11am advisory package.

Jeff Masters

Hurricane

Permalink

97L gets disrupted by Hispaniola

By: JeffMasters, 12:53 PM GMT am 21. Juli 2010

A tropical wave (Invest 97L) near the north coast of Hispaniola has been disrupted by interaction with the island, plus the effects of moderate wind shear of 10 - 20 knots. The storm is no longer a threat to develop into a tropical depression today, and the Hurricane Hunter flight that was scheduled for today has been postponed until Thursday. The disturbance has brought heavy rains of 8+ inches to Culebra, Vieques, the Virgin Islands, and some of the northern Lesser Antilles Islands. Wunderblogger Weather456 reported that the power was knocked out on the island of St. Kitts for about 24 hours, due to the intense lightning associated with 97L. All of Puerto Rico and the Virgin Islands are under flash flood watches today.

Satellite images of 97L show a relatively meager number of heavy thunderstorms that are not well-organized. The curved bands to the north and east of the center have disappeared, and there is no evidence of low-level spiral banding or of a surface circulation. Surface observations over the northern Dominican Republic show only light winds, with no westerly winds indicating that a surface circulation is forming. Long-range radar loops from San Juan show a much reduced amount of thunderstorm activity.


Figure 1. Total radar-estimate rainfall for 97L.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today, and to Haiti on today and Thursday. Heavy rains from 97L will affect eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas Thursday, and South and Central Florida can expect heavy rains to arrive Thursday night or Friday morning. The latest suite of model runs from 2am EDT this morning (6Z) foresee 97L making landfall on the Florida coast somewhere between Miami and Cape Canaveral on Friday, then continuing into the Gulf of Mexico on Saturday. Only the Canadian model foresees a threat to Texas, and the other models predict a second landfall between eastern Louisiana and the Florida Panhandle.

Intensity Forecast for 97L
The primary detriment to development of 97L today will be its close proximity to the landmass of Hispaniola. Once the storm pulls away from the island tonight, 97L has a better chance of development. Also hindering development over the next two days will be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next three days, which should allow for some steady development of 97L on Thursday and Friday before it reaches Florida. NHC is giving 97L a 60% chance of developing into a tropical depression by Friday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development before 97L reaches Florida is unlikely, due to the storm's current state of disorganization and the dry air over the Bahamas. It's very unlikely that 97L has time to organize into a hurricane before hitting Florida. I put the odds of 97L making it to hurricane strength before reaching Florida at 5%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over water in the Gulf, which is very uncertain. The environment in the Gulf of Mexico should be favorable for intensification, if passage over Florida does not disrupt the storm too much.

I'll have a new post Thursday morning, or earlier if there's a major change to 97L.

Famed climate scientist Steven Schneider dies
Steven Schneider, one of the most influential and talented climate scientists of our time, died on Monday. Ricky Rood has a tribute to Dr. Schneider in today's blog. Ricky comments, "He is known for feistiness. His last book was Science as a Contact Sport: Inside the Battle to Save Earth's Climate. He was a man who was, bluntly, harassed and threatened by those who did not like his message. He never shrank from the battle."

Jeff Masters

Hurricane

Updated: 08:33 PM GMT am 03. Januar 2012

Permalink

97L continues to grow more organized; headed for Bahamas and Florida

By: JeffMasters, 07:07 PM GMT am 20. Juli 2010

A tropical wave (Invest 97L) between Puerto Rico and the Dominican Republic has continued to become more organized today, and is a threat to develop into a tropical depression as early as Wednesday morning. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day, and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 15 knots, which should allow 97L to continue to develop today. Satellite images of 97L show a moderate area of steadily organizing thunderstorms, with curved bands developing to the north and east of the center. There are no signs of a surface circulation on satellite imagery or on the 10:38am EDT ASCAT pass. Surface observations show only light winds over Puerto Rico and the Dominican Republic, but the surface winds at Punta Cana on the eastern tip of the Dominican Republic have shifted to the west this afternoon, indicating that a surface circulation may be forming just north of that location. Long-range radar loops from San Juan do not show any evidence of a surface circulation. The Hurricane Hunter mission scheduled for today was canceled, but is scheduled to fly Wednesday afternoon.


Figure 1. Total precipitation from 97L as predicted by the 12Z (8 am EDT) July 20, 2010 run of the HWRF model. Image credit: Morris Bender, NOAA/GFDL.

Track Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of isolated flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. The latest suite of model runs from 8am EDT this morning (12Z) foresee a more northerly track for 97L into Central Florida. Several models develop 97L into a tropical storm, with both the GFDL and HWRF models predicting 97L will hit South or Central Florida as a tropical storm on Friday. Most of the models have 97L entering the Gulf of Mexico on Saturday, but the amount of time 97L has over the Gulf may be limited to a day or less if the storm ends up exiting into the Gulf near Tampa Bay. The NOGAPS model predicts a more southerly path across South Florida and into Louisiana.

Intensity Forecast for 97L
One factor potentially aiding development of 97L will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will stay in the moderate range, 10 - 20 knots, over the next five days. The primary detriment to development of 97L over the next three days will probably be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. If the center forms close to the coast of the Dominican Republic, the high mountains of Hispaniola may also be a problem for the storm. NHC is giving 97L a 60% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 70% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas. I put the odds of 97L making it to hurricane strength before reaching Florida at 30%, and I give a 20% chance it will be a hurricane in the Gulf of Mexico. The probability of 97L being a hurricane in the Gulf of Mexico will depend heavily upon how long the storm spends over land or interacting with land over the next four days, which is very uncertain.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 97
2) A look ahead at the coming two weeks

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

Hurricane

Updated: 08:33 PM GMT am 03. Januar 2012

Permalink

97L a threat to become a tropical depression on Wednesday

By: JeffMasters, 01:31 PM GMT am 20. Juli 2010

A tropical wave (Invest 97L) near the east coast of Puerto Rico has become more organized overnight and is a threat to develop into a tropical depression as early as Wednesday. The disturbance has brought heavy rains of 8+ inches to Culebra and Vieques islands over the past day (Figure 1), and all of Puerto Rico and the Virgin Islands are under flash flood watches today. The storm could bring an additional 3 - 6 inches of rain to the islands over the next two days. The upper level low centered a few hundred miles north of the Dominican Republic is no longer bringing high levels of wind shear to 97L; wind shear has fallen to the moderate range, 10 - 20 knots, which may allow 97L to continue to develop today. Satellite images of 97L show a moderate area of disorganized thunderstorms, but no signs of a surface circulation, no low-level spiral banding, and no upper-level outflow. There is a large amount of dry air to the northwest of Puerto Rico that will interfere with development of 97L. Surface observations show only light winds over Puerto Rico, with no signs of a surface circulation. The Hurricane Hunters are on call to investigate 97L this afternoon, if necessary.


Figure 1. Total radar-estimated rainfall from Invest 97L.

Forecast for 97L
The storm is in a fairly straightforward steering current environment, and 97L should progress steadily to the west-northwest through Saturday. The rains from 97L's thunderstorms will bring the threat of flooding to the Dominican Republic today and Wednesday, and to Haiti on Wednesday and Thursday. Heavy rains from 97L will begin moving into eastern Cuba, the Turks and Caicos Islands, and the eastern Bahamas on Wednesday, and South Florida can expect heavy rains to arrive as early as Thursday night. We do have several models developing 97L into a tropical depression or tropical storm. The GFS and HWRF both take 97L to tropical storm status over the Bahamas by Thursday, with the storm then tracking over South Florida on Friday and entering the Gulf of Mexico on Saturday. The NOGAPS is similar, but portrays a weaker system. All of these models foresee a threat to the oil spill region by Saturday night or Sunday, with the storm making a second landfall somewhere between the Florida Panhandle and Louisiana. One factor potentially aiding the storm will be the Madden-Julian oscillation, which currently favors upward motion over the Gulf of Mexico and Caribbean. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. Also in favor of development are the warm ocean temperatures of 29°C. The SHIPS model predicts shear will remain moderate, 10 - 20 knots, over the next 4 - 5 days, and I believe the primary detriment to development of 97L over the next two days will be the presence of dry, stable air in its path over the Bahamas, thanks to the upper-level low to the north of the Dominican Republic. NHC is giving 97L a 40% chance of developing into a tropical depression by Thursday, which is a reasonable forecast. I think there is a 60% chance 97L will eventually become Tropical Storm Bonnie, sometime in the next five days. Sudden rapid development today or on Wednesday is unlikely, due to the dry air over the Bahamas, and I put the odds of 97L making it to hurricane strength before reaching Florida at 10%. There is a better chance that 97L could attain hurricane strength in the Gulf of Mexico, perhaps 20%. These probabilities will depend heavily upon how long 97L (or Bonnie) spends over land or interacting with land over the next four days, which is very uncertain.

Time to cut the forecast numbers for the coming hurricane season?
Here are the number of Atlantic named storms, hurricanes, and intense hurricanes predicted by the various forecast groups in their late May or early June forecasts:

23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique (Note: TSR increased their numbers to 19.1, 10.4, and 4.8 with their July 6 forecast)
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology

The group forecasting the lowest activity was the Florida State University group led by Dr. Tim LaRow. They use a new dynamical forecast model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year's June forecast by the COAPS model called for 17 named storms and 10 hurricanes. However, Dr. LaRow emailed me yesterday to say that the COAPS model is now calling for reduced activity. Using the state of the atmosphere and ocean as of July 15, a new run of the COAPS model was performed over the weekend. The new forecast is now calling for two fewer hurricanes--a total of 15 named storms and 8 hurricanes (including Alex.) The COAPS model generated an "ensemble" of five different forecasts, done by varying the initial sea surface temperatures by a few percent at the beginning of the model run. These five forecasts came up with a range of 12 - 16 named storms (including Alex), and 7 - 10 hurricanes. It will be interesting to see when CSU issues its August 4 forecast if they also cut their numbers. With only one named storm (Alex) thus far this year, it's getting pretty hard to have a season with 19 or 20 named storms. Only four hurricane seasons since 1851 have had as many as nineteen named storms. These four seasons--1887, 1933, 1995, and 2005--all had at least three named storms by July 20.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 97
2) A look ahead at the coming two weeks

Today's show will be about 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

Hurricane

Updated: 08:33 PM GMT am 03. Januar 2012

Permalink

Russia records its hottest temperature in history; 97L forms near Puerto Rico

By: JeffMasters, 02:40 PM GMT am 19. Juli 2010

A heat wave of unprecedented intensity has brought the world's largest country its hottest temperature in history. On July 11, the ongoing Russian heat wave sent the mercury to 44.0°C (111.2°F) in Yashkul, Kalmykia Republic, in the European portion of Russia near the Kazakhstan border. The previous hottest temperature in Russia (not including the former Soviet republics) was the 43.8°C (110.8°F) reading measured at Alexander Gaj, Kalmykia Republic, on August 6, 1940. The remarkable heat in Russia this year has not been limited just to the European portion of the country--the Asian portion of Russia also recorded its hottest temperature in history this year, a 42.3°C (108.1°F) reading at Belogorsk, near the Amur River border with China. The previous record for the Asian portion of Russia was 41.7°C (107.1°F) at nearby Aksha on July 21, 2004.


Figure 1. Departure of temperature from average for July 11, 2010 for Russia. Russia's hottest temperature in history was recorded in Yashkul, 44.0°C (111.2°F). This was 9 - 10°C (16 - 18°F) above average. Image credit: NOAA/ESRL.

Moscow on track for its hottest July in history
According to the Russian weather service, the first fourteen days of July in Moscow averaged 6.2°C above average. The record hottest July, in 1938, had temperatures averaging 5.3°C above average, so Moscow is on track to set the record for its warmest July in history. The past four days, Moscow has averaged 8.2°C above average. The heat wave peaked on July 17, when the mercury hit 35.0°C (95°F). Moscow's hottest temperature of all-time is 36.6°C (98.2°F), set in August, 1920. With the wunderground.com forecast for Moscow calling for high temperatures between 31 - 38°C (88 - 100°F) for the coming week, no end to the heat wave is in sight. Weather records for Moscow extend back to 1879.

Russia's remarkable heat wave has led to a state of emergency to be declared for 19 of Russia's 83 provinces, and record number of Russians have been drowning in swimming accidents as they take to the water to escape the heat. Over 1200 Russians drowned in June, with another 233 dying between July 5 and 12. The heat has also created dangerous levels of air pollution in Moscow, and severely impacted agriculture.

Nine new national extreme heat records this year
As I commented in Friday's post, six nations in Asia and Africa set new all-time hottest temperature marks in June. Two nations, Myanmar and Pakistan, set all-time hottest temperature marks in May, including Asia's hottest temperature ever, the astonishing 53.5°C (128.3°F) mark set on May 26 in Pakistan. Last week's record in Russia makes nine countries this year that have recorded their hottest temperature in history, making 2010 the year with the most national extreme heat records. My source for previous all-time records is the book Extreme Weather by Chris Burt. I thank Mr. Burt and weather records researchers Maximiliano Herrera and Howard Rainford for their assistance identifying this year's new extreme temperature records.


Figure 2. Morning satellite image of tropical wave 97L near Puerto Rico, and another tropical wave near Jamaica.

Two tropical waves worth watching
A tropical wave passing over the Virgin Islands this morning will bring heavy rain and possible flooding to Puerto Rico today. This wave was designated Invest 97L by NHC this morning. The wave is under about 20 knots of wind shear, due to strong upper-level westerly winds. The strong upper-level winds are associated with the counter-clockwise flow of air around an upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico. Satellite images of 97L show a moderate area of disorganized thunderstorms to the north of Puerto Rico, but no signs of a surface circulation, low-level spiral banding, or upper-level outflow. There is a large amount of dry air to the north of Puerto Rico that will interfere with development of 97L. As the wave progresses west to west-northwest through Wednesday, thunderstorm activity will increase, due to interaction with the upper low. The rains from these thunderstorms will bring the threat of flooding to the Dominican Republic on Tuesday and Haiti on Wednesday. The upper low will also bring high wind shear of 20 - 30 knots over the the wave through Wednesday. No development of the wave is likely until at least Wednesday, when the SHIPS model predicts shear will fall to the moderate range, 10 - 20 knots. At that time, 97L will be over the eastern Bahamas and eastern Cuba. However, none of the reliable computer models is calling for tropical cyclone development over the next seven days. I expect 97L will enter the Gulf of Mexico early next week. NHC is giving 97L a 20% chance of developing into a tropical depression by Wednesday. The Hurricane Hunters are on call to fly into 97L Tuesday afternoon, if necessary.

A second region of concern is a tropical wave in the Western Caribbean, near Jamaica. This wave is currently producing widely scattered thunderstorms, and shows no signs of organization. However, wind shear is a light 5 - 10 knots over the wave, and we need to keep an eye on this one. The wave will continue to the west at 10 - 15 mph this week, and will bring the threat of heavy rain to Belize and Mexico's Yucatan Peninsula late this week. NHC is giving this wave a 20% chance of developing into a tropical depression by Wednesday.


Figure 3. Approximate oil spill location on July 18, 2010, estimated by NOAA using visible satellite imagery from NASA's MODIS instrument and Synthetic Aperture Radar (SAR) imagery from polar-orbiting satellites. Image credit: NOAA Satellite Services Division.

Wind and ocean current forecast for the BP oil disaster
East to southeast winds of 10 - 20 knots will blow in the northern Gulf of Mexico today through Friday, according to the latest marine forecast from NOAA. The resulting ocean currents should push the oil to the west and northwest onto the portions of the Louisiana nearest the Deepwater Horizon blowout location, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range outlook is uncertain, and will depend upon what 97L does. It's a pleasant relief to look at the trajectory maps and not see the usual bull's eye of high oil concentrations at the blowout site! However, there is still plenty of oil in the Gulf that will slosh onto shore in the coming weeks and months.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next post
I'll have a new post on Tuesday.

Jeff Masters

Heat Hurricane

Updated: 03:48 PM GMT am 19. Juli 2010

Permalink

Tropical wave bringing heavy rain to northern Lesser Antilles

By: JeffMasters, 01:57 PM GMT am 18. Juli 2010

A tropical wave near 18N, 60W is entering the northernmost Lesser Antilles Islands and is generating some disorganized heavy thunderstorm activity. This wave is under about 20 knots of wind shear, due to strong upper-level westerly winds. The strong upper-level winds are associated with the counter-clockwise flow of air around an upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico. As the wave progresses west to west-northwest through Tuesday, thunderstorm activity will increase, due to interaction with the upper low. The rains from these thunderstorms will bring the threat of flooding to Puerto Rico on Monday, the Dominican Republic on Tuesday, and Haiti on Wednesday. The upper low will also bring high wind shear of 20 - 30 knots over the the wave on Monday and Tuesday. No development of the wave is likely until at least Thursday, when it will be over the eastern Bahamas and eastern Cuba. At that time, shear is expected to drop below 20 knots, and the wave has the potential to develop. However, none of the reliable computer models is calling for tropical cyclone development over the next seven days. I expect that this wave will eventually enter the Gulf of Mexico early next week. NHC is giving the wave a 10% chance of developing into a tropical depression by Tuesday.


Figure 1. Morning satellite image of tropical wave entering the Lesser Antilles Islands.

Next post
I'll have a new post on Monday.

Jeff Masters

Hurricane

Updated: 02:04 PM GMT am 18. Juli 2010

Permalink

NOAA: June 2010 the globe's 4th consecutive warmest month on record

By: JeffMasters, 03:02 PM GMT am 16. Juli 2010

June 2010 was the warmest June since record keeping began in 1880, according to the National Oceanic and Atmospheric Administration's (NOAA's) National Climatic Data Center (NCDC), and was the fourth consecutive warmest month on record. NASA's Goddard Institute for Space Studies rated June 2010 the third warmest June on record, behind June 1998 and June 2009. Both NOAA and NASA rated the year-to-date period, January - June, as the warmest such period on record. June 2010 global ocean temperatures were the fourth warmest on record, while land temperatures were the warmest on record. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were the 2nd warmest on record in June, according to both the University of Alabama Huntsville (UAH) and Remote Sensing Systems (RSS) groups. The record warmest temperatures in the lower atmosphere were recorded in 1998.

For those interested, NCDC has a page of notable weather highlights from June 2010.


Figure 1. Departure of temperature from average for June 2010. Image credit: National Climatic Data Center (NCDC).

June 2010 features an unprecedented heat wave in Asia and North Africa
A withering heat wave of unprecedented intensity brought the hottest temperatures in recorded history to six nations in Asia and Africa, plus the Asian portion of Russia, in June 2010. At least two other Middle East nations came within a degree of their hottest temperatures ever in June.

The heat was the most intense in Kuwait, which recorded its hottest temperature in history on June 15 in Abdaly, according to the Kuwait Met office. The mercury hit 52.6°C (126.7°F). Kuwait's previous all-time hottest temperature was 51.9°C (125.4°F), on July 27,2007, at Abdaly. Temperatures reached 51°C (123.8°F) in the capital of Kuwait City on June 15, 2010.

Iraq had its hottest day in history on June 14, 2010, when the mercury hit 52.0°C (125.6°F) in Basra. Iraq's previous record was 51.7°C (125.1°F) set August 8, 1937, in Ash Shu'aybah.

Saudi Arabia had its hottest temperature ever on June 22, 2010, with a reading of 52.0°C (125.6°F) in Jeddah, the second largest city in Saudi Arabia. The previous record was 51.7°C (125.1°F), at Abqaiq, date unknown. The record heat was accompanied by a sandstorm, which caused eight power plants to go offline, resulting in blackouts to several Saudi cities.

In Africa, Chad had its hottest day in history on June 22, 2010, when the temperature reached 47.6°C (117.7°F) at Faya. The previous record was 47.4°C (117.3°F) at Faya on June 3 and June 9, 1961.

Niger tied its record for hottest day in history on June 22, 2010, when the temperature reached 47.1°C (116.8°F) at Bilma. That record stood for just one day, as Bilma broke the record again on June 23, when the mercury topped out at 48.2°C (118.8°F). The previous record was 47.1°C on May 24, 1998, also at Bilma.

Sudan recorded its hottest temperature in its history on June 25 when the mercury rose to 49.6°C (121.3°F) at Dongola. The previous record was 49.5°C (121.1°F) set in July 1987 in Aba Hamed.

The Asian portion of Russia recorded its highest temperature in history on June 25, when the mercury hit 42.3°C (108.1°F) at Belogorsk, near the Amur River border with China. The previous record was 41.7°C (107.1°F) at nearby Aksha on July 21, 2004. (The record for European Russia is 43.8°C--110.8°F--set on August 6, 1940, at Alexandrov Gaj near the border with Kazakhstan.

Two other countries came within a degree of their all time hottest temperature on record during the heat wave. Bahrain had its hottest June temperature ever, 46.9°C, on June 20, missing the all-time record of 47.5°C (117.5°F), set July 14, 2000. Temperatures in Quatar reached 48.8°C (119.8°F) on June 20. Quatar's all-time record hottest temperature was 49.6°C (121.3°F) set on July 9, 2000. All of these records are unofficial, and will need to be verified by the World Meteorological Organization (WMO.) The source for the previous all-time records listed here is the book Extreme Weather by Chris Burt. According to Mr. Burt, the only other time as many as six nations set their all-time highest temperature marks in a single month was during the European heat wave of August 2003.


Figure 2. Dust storm over Iraq on June 23, 2010, the day after Iraq recorded its hottest temperature in its history. Image credit: NASA.

June 2010 Arctic sea ice extent lowest on record
Northern Hemisphere sea ice extent in June 2010 was the lowest in the 31-year satellite record, according to the National Snow and Ice Data Center. The rate of ice loss during June was the fastest on record, approximately 50% faster than average. Ice volume was also at a record low through the first half of June, according to University of Washington Polar Ice Center. The record ice loss in June was due in large part to the presence of strong high pressure north of Alaska, combined with strong low pressure over Siberia, which drove warm air from Asia over the pole. This pressure pattern, called the Arctic Dipole, was unknown until the 2000s, and may be the result of climate change.

Eighth warmest June on record for the U.S.
For the contiguous U.S., it was the 8th warmest June in the 116-year record, according to the National Climatic Data Center. Three states had their warmest June on record: Delaware, New Jersey, and North Carolina. Seventeen states had a top-ten warmest June, with five of these recording their second warmest June ever (Maryland, Virginia, South Carolina, Florida, and Louisiana.) No state recorded a top-ten coldest June.

U.S. precipitation
For the contiguous U.S., June 2010 ranked as the 17th wettest June in the 116-year record. June precipitation was the wettest on record for Michigan. Several other states were also anomalously wet, including: Iowa (2nd wettest), Nebraska and Illinois (3rd wettest), Indiana (4th wettest), Wisconsin (5th wettest), Oregon (6th wettest), and Ohio (10th wettest). Maryland (6th driest) was the only state that experienced a top-ten driest June.

U.S. Climate Extremes Index
NCDC's Climate Extremes Index (CEI) for January - June was about 6 percent higher than average. The CEI measures the prevalence of several types of climate extremes (like record or near-record warmth, dry spells, or rainy periods). Factors contributing to the elevated 2010 value were large footprints of: extreme wetness (more than three times the average footprint), warm minimum temperatures ("warm overnight lows"), and areas experiencing heavy 1-day precipitation events.

U.S. tornadoes
According to NOAA's Storm Prediction Center, there were 387 preliminary tornado reports during June. If confirmed, this will be the second most active June on record, behind 1992. Minnesota had a particularly busy month with 67 preliminary tornado reports, besting the previous record of 35 tornadoes during June 2005.

The tropics are quiet
None of the reliable computer models is calling for tropical cyclone development over the next seven days. There is an area of disturbed weather off the coast of Costa Rica that is generating some heavy thunderstorm activity over the extreme Southwest Caribbean. This disturbance should move westward over Nicaragua and Honduras over the weekend, bringing heavy rains to Central America. NHC is giving this disturbance a 10% chance of developing into a tropical depression by Sunday.


Figure 3. My neighbor Tom Vance works to clear a fallen tree from the road so we can get out of our subdivision.

Next post
I'll have a new post on Monday at the latest. I may have trouble posting much this weekend, as a severe thunderstorm knocked out power to my neighborhood last night. I was watching the storm from my porch when the winds suddenly began gusting to 60 - 70 mph, and figured I'd better hustle inside when the huge black walnut tree in front of my house began thrashing like the Hogwarts whomping willow! Two neighbors had trees crash through their roofs, and downed power lines started several small fires.

Jeff Masters

Climate Summaries

Permalink

La Niña is here

By: JeffMasters, 01:16 PM GMT am 15. Juli 2010

The equatorial Eastern Pacific Ocean continues to cool, and we have now crossed the threshold into La Niña conditions. Sea surface temperatures (SSTs) over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", fell to 0.8°C below average by July 12, according to NOAA.. The Australian Bureau of Meteorology put this number at 0.7°C below average (as of July 11.) Since La Niña conditions are defined as occurring when this number reaches 0.5°C below average, we are well into the territory of a weak La Niña event. La Niña conditions must be present for several months before this will be officially classified as a La Niña event, but it is highly likely that a full-fledged La Niña event lasting at least eight months has arrived. We started out the year with a strong El Niño, so it may seem surprising that we have transitioned La Niña so quickly, However, historically, about 35 - 40% of El Niño events are followed by a La Niña within the same year. Given current trends, I expect the current La Niña to cross the threshold needed to be defined as "moderate" strength--temperatures at least 1.0°C below average in the equatorial Eastern Pacific--by September.


Figure 1. Progression of El Niño to La Niña over the past year, as measured by SSTs in the the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region". Image credit: NOAA Climate Prediction Center.

The implications
It is well-known that both the number and intensity of hurricanes in the Atlantic tend to increase during La Niña events. However, as I discussed in a post last month, since 1995, neutral years (when neither an El Niño or La Niña are present) have had Atlantic hurricane activity equal to La Niña years. The last time we had a strong El Niño event followed by a La Niña event in the same year, in 1998, we had a Atlantic hurricane season 40% above average in activity, with 14 named storms, 10 hurricanes, and 3 intense hurricanes. The season was relatively late-starting, with only one named storm occurring before August 20. I'm thinking this year's season may be similar, though four or more intense hurricanes are a good bet due to the record warm SSTs.

Both El Niño and La Niña events have major impacts on regional and global weather patterns. For the remainder of July and August, we can expect La Niña to bring cloudier and wetter than average conditions to the Caribbean, but weather patterns over North America should not see much impact (Figure 2.) Globally, La Niña conditions tend to cause a net cooling of surface temperatures. Thus, while the past twelve month period has been the warmest globally since record keeping began in 1880, it is unlikely that the calendar year of 2010 will set the record for warmest year ever.



Figure 2. Typical regional weather anomalies observed during June - August when La Niña conditions are present. The Caribbean tends to be cloudier and wetter than average, but there is typically little change to temperature and precipitation patterns over North America. Image credit: NOAA Climate Prediction Center.

The tropics are quiet
There are no threat areas to discuss in the Tropical Atlantic today, and none of the reliable computer models is calling for tropical cyclone development over the next seven days.

Next post
I'll have a new post on Friday.

Jeff Masters

Climate Summaries

Permalink

Typhoon Conson kills 18 in the Philippines; record SSTs continue in the Atlantic

By: JeffMasters, 01:27 PM GMT am 14. Juli 2010

Tropical Storm Conson hit the Philippines' main island of Luzon yesterday as a strong tropical storm with 70 mph winds. Conson was briefly the season's first typhoon on Monday, when it intensified to an 80 mph Category 1 storm. Conson is being blamed for at least 18 deaths in the Philippines, with 57 other people missing. The storm caused an extended power outage to the entire island of Luzon. Conson is headed towards a second landfall later this week in China, but should not intensify into a typhoon again because of the presence of 20 - 30 knots of wind shear. Conson is only the second named storm in what has been an unusually quiet Northwest Pacific typhoon season. According to Digital Typhoon, an average season has six named storms by mid-July.


Figure 1. Tropical Storm Conson as captured by the MODIS instrument on NASA's Aqua satellite at 4:55 UTC July 13, 2010. At the time, Conson was a tropical storm with sustained winds of 70 mph. Image credit: NASA.

June SSTs in the tropical Atlantic set a new record
Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes had their warmest June on record, according to an analysis I did of historical SST data from the UK Hadley Center. SST data goes back to 1850, though there is much missing data before 1910 and during WWI and WWII. SSTs in the Main Development Region (10°N to 20°N and 20°W to 80°W) were 1.33°C above average during June, beating the previous record of 1.26°C set in June 2005. June 2010 is the fifth straight record warm month in the tropical Atlantic, and the third warmest anomaly measured for any month in history. The only warmer anomalies were 1.51°C and 1.46°C, set in May 2010 and April 2010, respectively. As I explained in detail in a post on record February SSTs in the Atlantic, the Arctic Oscillation (AO) and its close cousin, the North Atlantic Oscillation (NAO), are largely to blame for the record SSTs, though global warming and Atlantic Multidecadal Oscillation (AMO) also play a role. The magnitude of the anomaly has fallen over the past month, since trade winds over the tropical Atlantic have increased to slightly above-normal speeds. These higher trade wind speeds are due to the fact that the Bermuda-Azores High has had above-normal surface pressures over the past month. The Bermuda-Azores High and its associated trade winds are forecast to remain at above-average strength during the next two weeks, according to the latest runs of the GFS model. This means that Atlantic SST anomalies will continue to fall during the remainder of July. However, keep in mind that we are talking about anomalies--the ocean will continue to warm until its usual early September peak in temperature, and it is likely that we will have the warmest or second warmest SSTs on record over the tropical Atlantic during the peak part of hurricane season, mid-August through mid-October.


Figure 2. The departure of sea surface temperature (SST) from average for July 12, 2010. Image credit: NOAA/NESDIS.

The tropics are quiet
There are no threat areas to discuss in the tropical Atlantic today, and none of the reliable computer models is calling for tropical cyclone development over the next seven days. The NOGAPS model is calling for a strong tropical disturbance to form off the Nicaragua coast this weekend. If this disturbance forms, it would move west-northwest and bring heavy rains to Nicaragua and Honduras early next week.

Next post
I'll have a new post on Thursday.

Jeff Masters

Hurricane

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More pre-season predictions of a very active Atlantic hurricane season

By: JeffMasters, 03:02 PM GMT am 12. Juli 2010

Hello again, it's Jeff Masters back again after a week away. Well, the past week was a wicked hot time to be in New England, where I was vacationing, and I certainly didn't expect to see 98° temperatures in Maine like I experienced! Fortunately, it's not hard to find cold water to plunge into in New England. Thankfully, the tropics were relatively quiet during my week away, and remain so today. There are no threat areas in the Atlantic to discuss at present, and none of the reliable computer models is forecasting tropical cyclone development over the next seven days. The NOGAPS model does show a strong tropical disturbance developing near the waters offshore of Nicaragua and Honduras this weekend, though. With not much to discuss in the present-day tropics, let's take a look at more pre-season predictions of the coming Atlantic hurricane season.

2010 Atlantic hurricane season forecast from Penn State
Dr. Michael Mann and graduate student Michael Kozar of Penn State University (PSU) issued their 2010 Atlantic hurricane season forecast on May 28. Their forecast utilizes a statistical model to predict storm counts, based on historical activity. Their model is predicting 19 to 28 named storms in the Atlantic, with a best estimate of 23 storms. The forecast assumes that record warm SSTs will continue in the Atlantic Main Development Region for hurricanes. Dr. Mann has issued two previous forecasts, in 2007 and 2009. The 2007 forecast was perfect--15 storms were predicted, and 15 storms occurred. The 2009 forecast called for 11.5 named storms, and 9 occurred (the 2009 forecast also contained the caveat that if a strong El Niño event occurred, only 9.5 named storms were expected; a strong El Niño did indeed occur.) So, the 2009 forecast also did well.


2010 Atlantic hurricane season forecast from the UK GloSea model
A major new player in the seasonal Atlantic hurricane season forecast game is here--the UK Met Office, which issued its first Atlantic hurricane season forecast in 2007. The UK Met Office is the United Kingdom's version of our National Weather Service. Their 2010 Atlantic hurricane season forecast calls for 20 named storms, with a 70% chance the number will range between 13 and 27. They predict an ACE index of 204, which is about double the average ACE index.

I have high hopes for the UK Met Office forecast, since it is based on a promising new method--running a dynamical computer model of the global atmosphere-ocean system. The CSU forecast from Phil Klotzbach is based on statistical patterns of hurricane activity observed from past years. These statistical techniques do not work very well when the atmosphere behaves in ways it has not behaved in the past. The UK Met Office forecast avoids this problem by using a global computer forecast model--the GloSea model (short for GLObal SEAsonal model). GloSea is based on the HadGEM3 model--one of the leading climate models used to formulate the influential UN Intergovernmental Panel on Climate Change (IPCC) report. GloSea subdivides the atmosphere into a 3-dimensional grid 0.86° in longitude, 0.56° in latitude (about 62 km), and up to 85 levels in the vertical. This atmospheric model is coupled to an ocean model of even higher resolution. The initial state of the atmosphere and ocean as of June 1, 2010 were fed into the model, and the mathematical equations governing the motions of the atmosphere and ocean were solved at each grid point every few minutes, progressing out in time until the end of November (yes, this takes a colossal amount of computer power!) It's well-known that slight errors in specifying the initial state of the atmosphere can cause large errors in the forecast. This "sensitivity to initial conditions" is taken into account by making many model runs, each with a slight variation in the starting conditions which reflect the uncertainty in the initial state. This generates an "ensemble" of forecasts and the final forecast is created by analyzing all the member forecasts of this ensemble. Forty-two ensemble members were generated for this year's UK Met Office forecast. The researchers counted how many tropical storms formed during the six months the model ran to arrive at their forecast of twenty named storms for the remainder of this hurricane season. Of course, the exact timing and location of these twenty storms are bound to differ from what the model predicts, since one cannot make accurate forecasts of this nature so far in advance.

The grid used by GloSea is fine enough to see hurricanes form, but is too coarse to properly handle important features of these storms. This lack of resolution results in the model not generating the right number of storms. This discrepancy is corrected by looking back at time for the years 1989-2002, and coming up with correction factors (i.e., "fudge" factors) that give a reasonable forecast.

The future of seasonal hurricane forecasts using global dynamical computer models is bright. Their first three forecasts have been good. Last year the Met Office forecast was for 6 named storms and an ACE index of 60. The actual number of storms was 9, and the ACE index was 53. Their 2008 forecast called for 15 named storms, and 15 were observed. Their 2007 forecast called for 10 named storms in July - November, and 13 formed. A group using the European Center for Medium Range Weather Forecasting (ECWMF) model is also experimenting with some promising techniques using that model. Models like the GloSea and ECMWF will only get better as increased computer power and better understanding of the atmosphere are incorporated, necessitating less use of "fudge" factors based on historical hurricane patterns. If human-caused climate change amplifies in coming decades, statistical seasonal hurricane forecasts like the CSU's may be limited in how much they can be improved, since the atmosphere may move into new patterns very unlike what we've seen in the past 100 years. It is my expectation that ten years from now, seasonal hurricane forecasts based on global computer models such as the UK Met Office's GloSea will regularly out-perform the statistical forecasts issued by CSU.

2010 Atlantic hurricane season forecast from Florida State University
Last year, another group using dynamical computer forecast models entered the seasonal hurricane prediction fray. A group at Florida State University led by Dr. Tim LaRow introduced a new model called COAPS, which is funded by a 5-year, $6.2 million grant from NOAA. This year, the COAPS model is calling for 17 named storms and 10 hurricanes. Last year's prediction by the COAPS model was for 8 named storms and 4 hurricanes, which was very close to the observed 9 named storms and 3 hurricanes.

Summary of 2010 Atlantic hurricane season forecasts
Here are the number of named storms, hurricanes, and intense hurricanes predicted by the various forecasters:

23 named storms: PSU statistical model
20 named storms: UKMET GloSea dynamical model
18.5 named storms, 11 hurricanes, 5 major hurricanes: NOAA hybrid statistical/dynamical model technique
18 named storms, 10 hurricanes, 5 intense hurricanes: CSU statistical model (Phil Klotzbach/Bill Gray)
17.7 named storms, 9.5 hurricanes, 4.4 intense hurricanes: Tropical Storm Risk (TSR), hybrid statistical/dynamical model technique
17 named storms, 10 hurricanes: FSU dynamical model
10 named storms, 6 hurricanes, 2 intense hurricanes: climatology

Only four hurricane seasons since 1851 have had as many as nineteen named storms, so 5 out of 6 of these pre-season forecasts are calling for a top-five busiest season in history. One thing is for sure, though--this year won't be able to compete with the Hurricane Season of 2005 for early season activity--that year already had five named storm by this point in the season, including two major hurricanes (Dennis and Emily.)

Tropical Storm Conson threatens the Philippines
Weather456 has an interesting post on why the Western Pacific typhoon season has been exceptionally inactive this year. It looks like we'll have out first typhoon of the Western Pacific season later today, since Tropical Storm Conson appears poised to undergo rapid intensification, and should strike the main Philippine island of Luzon as a Category 1 or 2 typhoon.

Next post
I'll have an update Wednesday.

Jeff Masters

Hurricane

Updated: 06:17 PM GMT am 14. Juli 2010

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Flooding Continues Along the Rio Grande

By: JeffMasters, 08:52 AM GMT am 10. Juli 2010

Hi everybody, Dr. Rob Carver filling in for Jeff while he's on vacation.

Things have quieted down in the tropics. No invests are active, and the tropical waves at sea don't have many thunderstorms associated with them. However, the moisture associated with Alex and TD Two is still bring widespread showers to Mexico/Texas which is contributing to flooding alon the Rio Grande. Here are several videos documenting the troubles along the Rio Grande.









Finally, here's a story about relief efforts in northern Mexico for villages cutoff by flood damaged roads and bridges.


Next update
Jeff should be back on Monday. Have a good weekend.

Hurricane

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Tropical Depression Two Along South Texas Coast

By: JeffMasters, 04:46 PM GMT am 08. Juli 2010

Hello everybody, this is Senior Meteorologist Shaun Tanner writing Dr. Masters' blog while he is on vacation.

Tropical Depression Two formed overnight in the northern Bay of Campeche and is now making landfall along the extreme south coast of Texas. A hurricane hunter was sent into the system and found a low-level circulation. While there are some reports of tropical storm strength winds in the squalls of the system, there is just not enough evidence to upgrade the storm to tropical storm strength before landfall.

The satellite representation of the depression is quite impressive as half of the depression is now over landfall. Brownsville radar currently is showing the effects of the depression with heavy rain and thunderstorms through much of southern Texas.

The biggest lingering effect from the depression will be to prolong the devastating flooding that has been ongoing in southern Texas and northeast Mexico. Not including the rain that will fall due to the depression, over the past 7 days, the area near Houston has received over 10 inches of rain, while some inland areas of Texas has received over 4 inches of rain. The problem gets worse in the Mexican state of Coahuila near the Texas border has received upwards of 20 inches of rain in the past 7 days due to substantial moisture pouring into the area.

This surging watershed has caused massive flooding throughout the region, with the area near Laredo, Texas and Nuevo Laredo, Mexico being the hardest hit. The flooding has caused the major border crossing between those two cities to be closed as the Rio Grande surged and threatened to top the crossing's bridge. A contingent of Mexican officials, including the mayor of Piedras Negras, Coahuila, touring the flooding damage in an airplane crashed Wednesday, killing all six onboard. Evacuations on both sides of the border has forced tens of thousands of people out of their homes, while over 100,000 people were without water service. The flooding problem is extra dangerous because swollen dams had to release some of their water downstream into areas that towns that have already been swamped. It was even reported that one of these releases by the National Water Commission of Mexico was the largest emergency water release in the country.

Needless to say, the rain from Tropical Depression Two will only further the flooding problems in southern Texas and northeast Mexico. Figure 3 shows the severe map and the greens represent Flood Watches and Warnings. You can see almost the entire states of Texas and Oklahoma are under these watches and warnings in anticipation of several inches of rain from the remnants of Tropical Depression Two.


Figure 1. Satellite loop of Tropical Depression Two.


Figure 2. Storm-centered radar as depression makes landfall.


Figure 3. Severe map.

Hurricane

Updated: 04:47 PM GMT am 08. Juli 2010

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Invest 96L: Organizing in the Gulf

By: JeffMasters, 01:17 AM GMT am 08. Juli 2010

Hi everybody, Dr. Rob Carver filling in for Jeff while he's on vacation.

Invest 96L appears to be in the process of developing into a tropical cyclone. The strength and extent of it's thunderstorms is much improved from yesterday (I used CIMMS tropical storm page for my analysis). It's under an upper-level anticyclone which promotes development because it efficiently removes "exhaust" from the thunderstorms. Shear is relatively low (~10 knots), and SST's are adequate for supporting a tropical cyclone (~28 deg. C). In the most recent Tropical Weather Outlook, NHC mentioned that research flights found that upper-level conditions were promising for storm development, so they assess the chances of 96L of becoming a tropical cyclone at 80%. My take is that 96L has an 80% chance of becoming TD #2, and about a 40% chance of being named Bonnie. My reasoning is that 96L has about 24 hours to intensify before interactions with land start interfering with intensification processes. Also, model intensity forecasts are not very supportive of 96L attaining tropical storm force winds. The model track forecast aids have 96L's center of circulation making landfall somewhere between Brownsville and Corpus Christi.

Impacts
The 12Z operational GFS, HWRF, NOGAPS, and 18Z NAM tell a similar story about the surface winds. Near tropical-storm force winds affect the Texas coast from Corpus Christi to Matagorda Bay. A broad area of 30+ mph winds also affects the Deepwater Horizon oil spill recovery efforts. The 12Z Canadian global model downplays the wind strengths, and the 12Z parallel GFS fails to develop any significant surface wind (> 20 mph). That said, I believe that 96L's greatest impact will be in the form of rain.

The Rio Grande from Del Rio to Laredo is either at major flood stage or is forecast to reach major flood stage in the next 24 hours. This is due to Alex and the moisture he brought to the high terrain of northern Mexico. Nearly all of the forecast models I've looked at forecast 2-3 inches of rain over the Rio Grande Valley in the next 5 days. That will only encourage more flooding. The main forecast problem is how much rain will fall along the Gulf Coast. The parallel GFS and HWRF suggest that 4.5 to 6.5 inches of rain will fall in the Galveston/Houston area in the next 5 days. In my opinion, people living in this area should be prepared for flooding.


Fig. 1. 120 hr accumulated precipitation (mm) for 12Z parallel GFS. Operational GFS


Fig. 2. 120 hr accumulated precipitation (mm) for 12Z HWRF.


Fig. 3. 120 hr accumulated precipitation (mm) for 12Z Canadian global model. NOGAPS

Emergency Preparations
People living along the Gulf coast from south of the Rio Grande to the Texas/Louisiana border should review their emergency preparations (hurricane preparations also make for good flood preparations). Jeff has put together a guide to hurricane preparedness with plenty of links for more information.

Next Update
If 96L becomes TD2 or Bonnie, I'll have an update tonight. Shaun Tanner may post something in the morning if that's when the naming occurs. Otherwise, I'll post a tropical update tomorrow afternoon.

Hurricane

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The Northeast Heatwave

By: JeffMasters, 09:08 AM GMT am 07. Juli 2010

Hi, Dr. Rob Carver, filling in for Jeff while he's on vacation.

The most significant weather event in the US on July 6, 2010 didn't show up on any radar. The geostationary satellites didn't see it in their constant watch over the Earth's atmosphere. Instead, the tale of this event was told by the thermometers, because the heatwave in the Northeast was the most significant event for July 6, and it will likely be the most important weather story for July 7.

The heat wave covers Pennsylvania to Maine, but Tuesday's worst was centered over New York City. All six of the stations used by the New York NWS office for climate reports (Central Park, La Guardia, JFK, Islip, Bridgeport, and Newark) set or tied the daily high temperature record. Newark and Central Park both reached 103 degrees F.

How unusual is this heat wave?
Figures 1 and 2 show how warm the highs and lows are compared to 30 year averages. Unless you were at the Great Lakes, the Midwest and Northeast have highs well above normal, with 10-15+ degree F differences over the coastal cities of the Northeast. Using my gridded temperature data, the low for New York City was 6 degrees F above normal, which should happen 30% of the time (1.1 standard deviations away from normal). The high was roughly 20 degrees above normal, which should happen only 0.29% of the time (3.04 standard deviations away from normal). This is an unusually strong heat wave.

Why it's hot
Basically, it's because there is "the Bull of a high pressure ridge [over the NE US]" to quote the Mount Holly NWS office forecast discussion. The large ridge of high pressure is forcing air to slowly descend across the Northeast, preventing clouds from forming. Without no clouds and plenty of daylight, the Sun heats the ground which then heats the air.

When will it cool down?
That's an excellent question. A trough of low pressure off the coast will bring onshore winds to the Tri-State area and MA by Thursday, so they should cool down a bit. The southern part of the heat wave, DC and Philadelphia, will have to wait for a cold front to arrive from the Great Lakes sometime Saturday to get relief.

Population affected
As Figure 3 shows, heat advisories covered most of the urban areas of the northeastern US. By my calculations, over 32 million people were under a heat advisory. Different offices have different guidelines for heat advisories. The NWS office responsible for New York issues a heat advisory if the heat index will be above 95 deg. F for two or more days or if the index will be above 100 deg. F for any length of time.


Fig.1 Plot of the difference between maximum temperature (the high for the day) and average maximum temperature in degrees F for July 6.


Fig.2 Plot of the difference between minimum temperature (the low for the day) and average minimum temperature in degrees F for July 6.


Fig.3 Plot of the active heat advisories across the northeastern US for July 6.

Heatwave impacts
The predominant impact from heat waves is increased mortality. CDC estimates that over 8,000 people died during heat waves from 1979 to 2003. That's more than all of the deaths due to lightning, flooding, tornadoes, hurricanes, and earthquakes. The elderly, sick, poor, and very young face the worst of the effects of the heat. Wikipedia has an interesting article describing the Chicago Heat Wave of 1995, a modern heat wave with a large number of fatalities due to the heat.

Heatwave coping strategies
The Centers for Disease Control have some tips for dealing with the heat. In summary, drink plenty of water, spend time in air-conditioned buildings, and wear light-colored clothing.

Is this heat wave due to global warming?
Ah, the $64,000 question. In the absence of detailed analysis, it's hard to specify the exact cause for this heat wave, from a meteorological or climatological view point. However, events like this are consistent with research showing that heat waves are more likely with
global warming
. I like the metaphor of loaded dice, global warming is not specifically responsible for any heat wave, but it will make them happen more often.

Tropics
My thinking on Invest 96L is unchanged from this blog entry. In summary, I believe that 96L has a <50 % chance becoming a tropical cyclone before it makes landfall. If it does so, it will likely be near the coast when that happens. In any event though, the winds and waves it generates will likely disrupt oil spill recovery efforts. Also, I would expect a broad area of showers and 20+ mph winds will affect the Gulf coast somewhere from south Texas to Louisiana.

Next update
I'll have an update this afternoon to talk about the tropics.

Heat

Updated: 09:42 AM GMT am 07. Juli 2010

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Invest 96L: Not Looking So Good

By: JeffMasters, 11:40 PM GMT am 06. Juli 2010

Hi everybody, Dr. Rob Carver filling in for Jeff while he is on vacation.

Invest 96L is currently over the Yucatan peninsula and is not looking as impressive as it did over the holiday weekend. Right now, the cloud tops are warming, which indicate that the thunderstorms are weakening. This is likely due to 96L's being ashore right now. Looking into the future, 96L's doesn't show much promise of becoming a significant tropical cyclone. Nearly all of the model guidance has 96L moving in a northwesterly direction along the cool waters churned up in Alex's wake. It looks like 96L will miss the warm SST's at 25N, 87W. It's also expected to move from low shear to higher shear over the the Gulf of Mexico. The ocean offshort of the coastal bend of Texas (Corpus Christi to west of Houston) may allow 96L to intensify if it gets there. There is a small band of warm SST's at the continental shelf, and the wind shear is low (<10 knots).

Looking at the dynamical model output, the story is still murky. Looking at the broad picture, a broad area of 20+ mph winds will affect the Gulf coastline somewhere between Corpus Christi and southeast Louisiana. NAM favors SE Louisiana, while GEM and the parallel GFS favor the coast east of Corpus Christi. HWRF and NOGAPS have the wind affecting the coast west of Houston, while the operational GFS has the wind coming ashore east of Houston. NOGAPS and HWRF are also the only models that show surface winds that are tropical storm force.

I think that that the upper-level circulation and the surface circulation are not strongly coupled together in teh model simulations. This would explain the the discrepancies between the wind swaths I'm describing and the hurricane forecast aids. Those aids use an automatic process to identify the vortex center in the model data that may favor upper-level features for tracking instead of surface features.

To sum it all up, I believe that 96L has a <50 % chance becoming a tropical cyclone before it makes landfall. If it does so, it will likely be near the coast when that happens. In any event though, the winds and waves it generates will likely disrupt oil spill recovery efforts. Also, I would expect a broad area of showers and 20+ mph winds will affect the Gulf coast somewhere from south Texas to Louisiana.


Fig. 1 Plot of maximum winds (mph) over the next 5 days from the 12Z GFS. Parallel GFS wind swath.


Fig. 2 Plot of maximum winds (mph) over the next 5 days from the 12Z NOGAPS. Canadian Global wind swath.


Fig. 3 Plot of maximum winds (mph) over the next 5 days from the 12Z HWRF.


Fig. 4 Plot of maximum winds (mph) over the next 5 days from the 18Z NAM.

Next Update
Tweaks later tonight as necessary, possibly a late night entry describing the Northeast heat wave. Tropical update will be posted Wednesday afternoon.

Hurricane

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Invest 95L Brushes Louisiana Coastline

By: JeffMasters, 12:42 AM GMT am 06. Juli 2010

Hi all,

Dr. Rob Carver, filling in for Jeff this week.

Midnight CDT Update
The low known as Invest 95L stopped it's northward progression and is now moving west along the Louisiana coastline. This is the oddest mesoscale convective complex/tropical feature I've seen in awhile. It's still producing a lot of rain, 2+ inches inland and 6+ inches over the ocean.


Base reflectivity from Lake Charles, LA at 11PM July 5 showing a very nice comma head. Animated loop.


Invest 95L is making landfall now in southern Louisiana near Terrebonne Bay. A CMAN station in Terrebonne Bay is currently reporting winds from the SE at 21 mph and the pressure is 1009 mb. Looking at the radar data, Invest 95L never had convection around the center of circulation. Also, it was hard to see a distinct surface circulation in the different analyses available. I believe soaking rains for southern Lousisana are going to be Invest 95L's main legacy. It's already produced 5+ inches of rain in some offshore locations according to radar-derived rainfall estimates.


Fig. 1 Meteogram for TRBL1 in Terrebonne Bay, LA. Tabular data are here.


Fig. 2 Base reflectivity from New Orleans, LA at 706PM, July 5. Animated loop.

Invest 96L
430 AM Update
In sum, the 00Z model runs don't present a different picture. It is curious to note that the Canadian Global model does not intensify 96L at all in the 00Z run, while NOGAPS has shifted towards a SE Louisiana landfall. I think the following discussion is still valid.

96L is going to be an interesting feature to forecast. It's still on the edge of a strong wind shear gradient. 40+ knots of shear are on the NE side of 96L, and <10 knots are on the SW side. The "center" of 96L is under about 15 knots of shear. This is likely inhibiting 96L. Nearly all forecast models take 96L NW through the Yucatan peninsula and into the Gulf of Mexico. Near the Yucatan itself, sea-surface temperatures are relatively cool, not the best environment for intensification. However, at 25N, 87W there is a hotspot of SST's, which would promote rapid intensification. However, there's currently 20 knots of shear over the hotspot, so the thunderstorms that do form as a result will be well ventilated, and not cause 96L to intensify.

The dynamical models have different takes on how 96L intensifies in the next 120 hours. The 18Z operational GFS strongly intensifies 96L over the hotspot and takes 96L towards Grand Isle, LA. The parallel (for testing model configuration changes) GFS has a similar track, but does not strengthen 96L as much. This indicates uncertainty on how the models are handling the upper-level winds.

The 18Z HWRF solution is much like the parallel GFS solution. The 12Z Canadian global model has a more westerly track, pushing 96L towards Port Arthur, but it strengthens 96L right before it makes landfall, not when it's over open water. NOGAPS takes the "a little from column A, a little from column B" approach, with a spinup over the hotspot (op. GFS solution), but a westerly landfall (the Canadian solution). More data to initialize the models from synoptic reconnaissance flights will help reduce uncertainty.

The bottom line, 96L will move into the Gulf of Mexico and is then shrouded by the mists of uncertainty. I also think that it's a possibility (>50%) that it will become a tropical cyclone sometime in the next 48-72 hours (leaning towards sometime in day 2-3 based on the model runs.)


Fig. 3 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 GFS model run.Parallel GFS version.


Fig. 4 Plot of maximum winds (mph) for the next 120 hours from the 18Z July 5 HWRF model run.


Fig. 5 Plot of maximum winds (mph) for the next 120 hours from the 12Z July 5 CMC global model run.NOGAPS wind swath.

Next update
I'll probably tweak this blog later tonight as new model runs come in. I'll have a full update tomorrow afternoon (Pacific time).

Hurricane

Updated: 09:46 AM GMT am 06. Juli 2010

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A Tale of Two Invests

By: JeffMasters, 12:17 PM GMT am 04. Juli 2010

Good morning, everybody, Dr. Rob Carver filling in for Jeff on Independence Day.

Currently, NHC is monitoring two different areas for possible tropical cyclone development. Invest 95L is about 125 miles west-southwest of the mouth of the Mississippi and it doesn't have much thunderstorm activity associated with it. Dry air from the north and strong wind shear have weakened it considerably from yesterday, and NHC believes it has a 10% chance of becoming a tropical cyclone before the feature makes landfall.

Invest 96L is in the western Caribbean sea and bears watching closely. Earlier in the morning, the convection was all on the east side of the circulation center, but thunderstorms have developed on the southwest side. According to the CIMMS wind shear analysis, 96L is on the outskirts of a low wind shear region just east of the Yucatan peninsula. It's also over warm SST's (>29 deg C), so it could intensify. NHC gives it a 20% chance of becoming a tropical cyclone in the next 48 hours. Computer models have 96L going through the Yucatan Channel then turning left and making landfall somewhere near the Rio Grande.


Fig. 1 IR satellite composite from 720AM EDT.

Next Update
My next post will be sometime Monday afternoon/evening. If the situation changes significantly before then, I'll make a new post. In any event, enjoy the holidays...

Hurricane

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Gulf of Mexico disturbance 95L worth watching

By: JeffMasters, 06:02 PM GMT am 03. Juli 2010

A cold front that pushed off the Southeastern U.S. and Gulf Coast has stalled out over the waters immediately offshore. An area of low pressure, Invest 95L, has developed in the Gulf of Mexico, about 100 miles southeast of the Deepwater Horizon oil disaster. Satellite loops show that this low does have a broad surface circulation, but heavy thunderstorm activity is being limited by 15 - 20 knots of wind shear. Water Vapor satellite loops show that 95L is embedded in a large region of dry air associated with an upper-level cold-cored low pressure system, and this dry air will hinder 95L's development. The cold, dry air associated with this upper-level low is giving 95L a subtropical appearance, with the main heavy thunderstorm activity (to the south) located well away from the center of circulation. NHC is giving 95L a 20% chance of becoming a tropical or subtropical depression by 2pm Monday. Wind shear is forecast to be in the 20 - 30 knot range Sunday through Monday, so any development of 95L should be slow. The disturbance is moving west at about 10 - 15 mph, and a general westward motion towards Texas should continue through Monday. None of the reliable computer models develop 95L into a depression. The Hurricane Hunters are on call to investigate 95L on Sunday, if necessary.

Elsewhere in the tropics, we should keep an eye on the region to the east of South Carolina for possible development, as well as the western Caribbean. None of the reliable models is showing a tropical storm developing in the Atlantic over the coming week, though.


Figure 1. Afternoon satellite image of Invest 95L.

Next post
I am on vacation for the coming week, and Dr. Rob Carver will be handling most or all of the blogging duties July 5 - July 12. One of us will be posting on July 4 if there is a major development to report.

Jeff Masters

Hurricane

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Alex is gone; the tropics are relatively quiet

By: JeffMasters, 12:55 PM GMT am 02. Juli 2010

Hurricane Alex is gone, killed by the high mountains of northern Mexico. Alex's rains linger on, and will continue to cause flooding problems in northern Mexico today. Alex killed at least 24 people in its week-long traverse of the Caribbean and Gulf of Mexico. One death occurred in the Dominican Republic, and fourteen were killed in Central America. In Mexico, the outer rainbands of the storm killed three in Acapulco, one person in Oaxaca, and one person in Chiapas. Following its final landfall, Alex caused at least eight deaths in Nuevo León, with three persons reported missing. It is possible Alex will have its named retired, though I think it unlikely. One of the countries substantially affected by a hurricane must make a request to the World Meteorological Organization (WMO) to have the hurricane's name required. Mexico was the country most affected by Alex, and Mexico has been reluctant to make retirement requests in the past. For example, Mexico suffered two landfalls from Category 5 Hurricane Emily in 2005, yet did not request that Emily's name be retired; there will be a new storm named Emily next year.

I hope Alex will give the officials in charge of the BP oil disaster a bit of a wake up call. We've been told that five days are required to shut down operations in the event of tropical storm force winds are forecast for the clean-up region. It is very unrealistic to expect a five day warning, since the average track error in a 5-day forecast is about 300 miles. Furthermore, we have little skill forecasting the formation of tropical storms, and it is often the case that a tropical storm forms just a 1-day journey from the Deepwater Horizon blowout location. If we examine the incidence of tropical storm force winds in that region over the past five years, I suspect that they were successfully predicted five days in advance perhaps 30% of the time.


Figure 1. Microwave satellite image of Alex at landfall. Image credit: Navy Research Lab.

The tropics are relatively quiet
A cold front that pushed off the Southeastern U.S. and Gulf Coast has stalled out over the waters immediately offshore. Some of the models give support for an area of weak low pressure to develop over the northern Gulf of Mexico along this front. NHC is giving a 10% chance of a tropical depression forming by 8am Sunday over the northern Gulf of Mexico. The GFS model is also indicating development may occur by the middle of next week along the portion of the front offshore from South Carolina. There is also some suggestion by several models that a strong tropical disturbance may form by the middle of next week in the Gulf of Mexico's Bay of Campeche, or in the Western Caribbean. At this point, none of these possibilities are worthy of significant concern, though we'll keep to keep an eye on them.

I'll have an update Saturday afternoon. Have a great holiday weekend, everyone!

Jeff Masters

Hurricane

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Alex, strongest June hurricane in 44 years, is now a tropical storm

By: JeffMasters, 02:20 PM GMT am 01. Juli 2010

Hurricane Alex, the strongest June hurricane in 44 years, is Tropical Storm Alex, thanks to passage over the rugged terrain of Mexico. Alex made landfall at 9pm CDT last night, 110 miles south of Brownsville, Texas, as a Category 2 hurricane with 105 mph winds. Alex was the strongest June hurricane since Hurricane Alma of 1966, which had 125 mph winds as it skirted the west coast of Florida. Brownsville long-range radar shows that Alex's heavy rains continue to pound the Texas/Mexico border region, and satellite estimates of rainfall (Figure 1) show that some of Alex's spiral bands dumped rains in excess of five inches today, in addition to the 5+ inches that fell yesterday. The Brownsville airport received 6.46" of rain as of 8am CDT today from Alex. Alex is being blamed for at least thirteen deaths in Central America and Mexico due to flooding, though none of these deaths occurred in the region where the storm made landfall. Alex spawned two tornadoes that hit South Texas, and there were at least four other reports of tornado funnel clouds that did not touch ground. Alex may continue to spawn isolated tornadoes today over South Texas and northern Mexico.


Figure 1. Radar-estimated rainfall so far today for Alex.


Figure 2. Snapshot of the Brownsville long-range radar showing Hurricane Alex at landfall at 8pm CDT Wednesday June 30, 2010.


Figure 3. Alex nearing landfall in northeastern Mexico at 12:10 CDT June 30, 2010, as seen by the MODIS instrument on NASA's Terra satellite. Image credit: NASA.

Storm Surge
Alex's maximum storm surge occurred along a 50-mile stretch of the Mexican coast centered about 75 miles south of Brownsville, Texas. The National Hurricane Center Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model predicted that the maximum water depth at the coast reached about 5 - 6 feet above ground level (Figure 3.) A storm surge of 1 - 2 feet was predicted by SLOSH for the Brownsville, Texas region. A storm surge of about 2 feet was observed in South Texas at the South Padre Island Coast Guard Station and Port Isabel.


Figure 4. Hurricane Alex's Maximum Water Depth (storm tide minus the elevation of the land it is passing over) computed using the primary computer model used by the National Hurricane Center (NHC) to forecast storm surge--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. The accuracy of the SLOSH model is advertised as plus or minus 20%. The maximum surge occurred to the right of where Alex's core made landfall, over a sparsely populated marshy area. This "Maximum Water Depth" image shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of five feet above mean sea level, and the combined storm surge and tide (the "storm tide") is ten feet at your location, the water depth image will show five feet of inundation. For more information on storm surge, consult our detailed storm surge pages.

Alex in historical context
Alex is the first June hurricane since Hurricane Allison of 1995. There have been only eleven hurricanes in May or June since 1945; only four of these were major Category 3 or higher storms.

Alex's bizarre behavior
Alex had several rather remarkable features I've never seen in a hurricane. Firstly, it underwent an eyewall replacement cycle as a Category 1 hurricane with 80 mph winds. Usually, we don't see the inner eyewall collapse and an eyewall replacement cycle occur until a hurricane reaches Category 3 strength. I've seen it happen on occasion to a Category 2 storm, but never a Category 1. Secondly, after Alex's inner 9-mile diameter eyewall collapsed at 10am EDT yesterday morning, an outer spiral band began to become the new eyewall. Winds in this outer spiral band/new eywall increased as the day progressed, as typically happens in an eyewall replacement cycle. However, part way through that process, Alex suddenly reversed course, and was able to build a small inner eyewall with a 12-mile diameter that was completed by landfall. I've never seen a hurricane change its mind in the middle of an eyewall replacement cycle and build an inner eyewall so fast. Finally, Alex had an unusually weak winds, considering how low the pressure was. The pressure was more typical of a hurricane one Saffir-Simpson category stronger than what the surface winds suggested.

Elsewhere in the tropics
The latest run of the NOGAPS model predicts the formation of a tropical depression the Western Caribbean on Tuesday. None of the other models is showing tropical development worthy of concern over the coming seven days.

Wind and ocean current forecast for the BP oil disaster
Alex is continuing to generate very rough conditions over the Deepwater Horizon blowout location, with 5 - 9 foot waves and 3 - 4 foot swells. The wind and seas will gradually subside today, according to the latest marine forecast from NOAA. The resulting currents induced by Alex's strong winds will push oil to many protected bays and estuaries that haven't seen oil yet. The latest trajectory forecasts from NOAA and the State of Louisiana show oil will also move westward along the central Louisiana coast towards the Texas border. Winds will decrease to 5 - 15 knots Friday through Tuesday but remain mostly out of the southeast, keeping the pressure on the regions of coast in Louisiana, Alabama, and Mississippi that are seeing oil hit their shores this week.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next post
I'll have an update Friday morning. Dr. Rob Carver plans on summarizing Alex in his blog later today.

Jeff Masters

Hurricane

Updated: 08:36 PM GMT am 03. Januar 2012

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Category 2 Alex Makes Landfall on the Mexican Coast

By: JeffMasters, 01:27 AM GMT am 01. Juli 2010

Hi, Dr. Rob Carver filling in for Jeff on the late shift.

1AM CDT Update
Alex is weakening as it moves inland As of the 1AM advisory, Alex's winds have slowed to 85 mph. Alex is at 24.1N, 98.2W which is 35 miles northwest of La Pesca, MX and 135 miles south-southwest of Brownsville, TX. Alex is moving west-southwest at 10 mph. Alex may be slowing down, but it's still producing a lot of rain. Radar-derived rainfall estimates shows that Alex is covering widespread areas with 0.5-0.8 inches of rain in the last hour. Over the past 24 hours, the Rio Grande at Brownsville has risen 10 feet, but it's still about 14 feet away from the flood stage of 27 feet.

9PM CDT
The center of Alex's eye has made landfall according to NHC. They state that 9PM CDT, Alex's center crossed the shoreline in the municipality of Soto La Marina, MX, which is 110 miles south of Brownsville. At the time of landfall, Alex had wind speeds of 105 mph, making it a Category 2 storm on the Saffir-Simpson hurricane wind scale

With wind speeds near 100 mph, Alex is nearing landfall on the Mexican coast. As of 8PM CDT, Alex is at 24.3N, 97.5W, 40 miles northeast of La Pesca, MX and 110 miles south of Brownsville. It is moving west at 10 mph, and the center of the eye should arrive onshore around 9PM CDT. Alex has a very large circulation, hurricane force winds extend 70 miles away from the the center, and tropical storm force winds are 205 miles away. A MADIS station located in South Padre Island, TX has reported wind gusts of 60 mph and sustained winds of 35-40 mph. We have a plot of that station's data here, and it looks like the wind speed sensor failed around 733PM CDT. Unfortunately, that's a common fate for weather stations near a landfalling storm.

One of the last eye penetrations of Alex occured at 640PM CDT, and they found an partially complete eye with a 12 mile radius. The minimum central pressure was 948 mb, a 2 mb drop since the 6PM update, and the maximum wind estimate was 94 mph using the microwave radiometer.


Fig. 1Base reflectivity from KBRO showing Alex's eye at 721PM CDT.

Threat from winds
Hurricane force winds are likely taking place along the northeast Mexican coast right now. 25 mph winds with stronger gusts are being reported in the Brownsville area. A tornado watch is currently in place for the south Texas coast. SPC shows there have been 5 tornado reports so far.

Threat from rain
Radar-derived rainfall estimates suggest that up to 9 inches of rain have fallen in some locations near Brownsville, TX. 5+ inches of rain has fallen over a widespread area in the Rio Grande valley. The NWS office in Brownsville is forecasting a total of 6-12 inches rain across the Valley, with 12-15 inch totals possible in isolated locations. Flooding similar to that caused by Dolly in 2008 is expected across south Texas.

Threat from coastal flooding
The NWS is predicting a 3-4 foot storm surge for the coast from Brownsville to Port Isabel, TX. They think the coastal flooding will be limited and not cause significant damage to property along the coast.

Next update
I'll try to edit this blog with updates as more information comes in tonight. Jeff should have a full posting tomorrow morning, and I'll likely have a post describing the flooding at my blog Thursday night.

Hurricane

Updated: 08:36 PM GMT am 03. Januar 2012

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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