Alex building an eyewall, still not a hurricane
Tropical Storm Alex is slowly building an eyewall, which is now more than 50% complete, according to recent satellite imagery and microwave images (Figure 1.) Satellite loops show a slot of dry air is spiraling into the center of the storm, and until this dry slot gets closed off, Alex will not be able to intensify significantly. Alex's heavy thunderstorms and low level spiral bands continue to slowly increase, but upper-level outflow is mediocre to the north and east, and absent elsewhere. The Hurricane Hunters are in the storm and have not found any hurricane-force winds at the surface yet.
Figure 1. Microwave "radar in space" image taken at 10:11 am CDT Tuesday June 28, 2010, showing that Alex had built an eyewall a little more than 50% complete. Image credit: Navy Research Lab.
Impacts
Alex is already bringing bands of heavy rain to the coasts of Texas and Mexico, as seen on the Brownsville, Texas radar. Hurricane local statements with projections for how Alex will affect the coast are now being issued by the National Weather Service in Brownsville and Corpus Christi. Since Alex is a large storm, it will have a storm surge that will affect most of the South Texas coast. NHC is giving a 40% - 60% chance of a storm surge of at least 3 feet affecting the Brownsville area, and 10% - 30% chance the surge will exceed 5 feet. In theory, a Category 2 hurricane moving WNW at 5 mph can bring a storm surge of up to 8 - 9 feet to the South Texas coast (Figure 2.) However, Alex is now unlikely to get that strong, and the surge should be less. Flooding damage from the expected 6 - 12 inches of rain from Alex will also be a major concern, as will wind damage. The combined wind, surge, and flooding damage from 2008's Hurricane Dolly, which hit near Brownsville, were about $1.05 billion. Dolly was a Category 2 hurricane offshore that weakened to a Category 1 hurricane with 85 mph winds when it made landfall. I expect Alex will be similar in its impacts to Dolly, though Alex's storm surge damage is likely to be greater. If Alex hits more than 50 miles south of the Texas border, as currently appears likely, the damage will be far less, since this region of the coast is relatively sparsely populated.
Figure 2. 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 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. This Maximum of the "Maximum Envelope of Waters" (MOM) image was generated for high tide, and thus shows the worst-case inundation scenarios for a mid-strength Category 2 hurricane moving WNW at 5 mph. For more information on storm surge, consult our detailed storm surge pages.
Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models confirm the faster movement of Alex to the coast, and residents in the affected areas now have 12 hours less to prepare for Alex's arrival than it seemed with yesterday's forecasts. Conditions will begin to deteriorate along the coast late tonight, so today is the day to finish preparations if you live near the Texas/Mexico border! The ridge that is steering Alex to the northwest is expected to strengthen today and Wednesday, which should push Alex on a more west-northwest and then westerly track on Wednesday. A few models even have Alex moving west-southwest by the time it makes landfall. The most northerly landfall location, near Brownsville, is predicted by the HWRF model.
To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 4am CDT (9 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:
Brownsville, TX: 88% chance of tropical storm conditions (winds 39+ mph), 23% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.
Corpus Christi, TX: 42% tropical storm, 1% hurricane.
La Pesco, MX: 37% tropical storm, 3% hurricane.
Freeport, TX: 18% tropical storm, 0% hurricane.
Tampico, MX: 14% tropical storm, 0% hurricane.
Galveston, TX: 13% tropical storm, 0% hurricane.
Intensity forecast for Alex
Alex is over a region of ocean with a warm, clockwise rotating Loop Current eddy that broke off from the Loop Current in July 2009 and moved west-southwest over the past 11 months. This eddy has moderately high total ocean heat content . Wind shear has fallen to a low 5 knots, and is projected by the SHIPS model to remain in the low range, below 10 knots, this afternoon and Wednesday. The combination of low wind shear and moderately high ocean heat content should allow Alex to intensify into a Category 1 hurricane, but time is running out for it to be a Category 2 hurricane. NHC is giving Alex a 79% chance of being a hurricane on Wednesday morning, and a 4% chance it will be a major hurricane at that time. Water vapor satellite images show the amount of dry air over the western Gulf of Mexico has decreased over the past day, though as I noted above, the dry slot wrapping into Alex's core is currently keeping the storm from closing off an eyewall. Dry air may turn out to be an increasing detriment to Alex on Wednesday as the storm approaches land. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. I don't expect Alex to stall out again, so slow motion leading to upwelling of cold water will probably not be a problem for Alex. The main issue limiting intensification will be the fact that Alex is so large, and it takes more time for a large storm to organize. Thus, I think Alex has only a 10% chance of intensifying into a major hurricane before landfall.
Elsewhere in the tropics
The last few runs of the NOGAPS model have been predicting the formation of a tropical disturbance off the coast of Nicaragua on Friday or Saturday that will move northwestward towards western Cuba. The GFS model, and the two models that use it for starting conditions, the GFDL and HWRF, are indicating the possibility that a weak extratropical storm may form along coastal Alabama this weekend. It is unlikely that such a storm would be over water long enough to transition to a tropical storm.
Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex's winds will not directly affect the oil slick location. However, because Alex is such a deep low pressure region, strong southeast to south winds of 10 - 20 knots will blow over the oil slick region today through Thursday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border. Alex is currently bringing swells of 3 - 4 feet to the coastal regions impacted by the oil slick, and these swells will increase to 6 - 8 feet on Wednesday. Wave heights will increase to 5 - 7 feet on Wednesday. Alex is expected to bring a storm surge of 1 - 2 feet along the coast in the oil spill region. The swells and waves that will accompany these high water levels will act to push oil deep into the marshlands in some locations. The long range forecast for the oil slick region is uncertain, due to the possibility a weak area of low pressure might develop late this week along the remains of a cold front draped across the region.
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
"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) Alex
2) A look ahead at what may happen the rest of hurricane season
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.
Next post
I'll have an update Wednesday morning by 9:30am CDT. Rob Carver is planning on doing a late-night update tonight.
Jeff Masters
Reader Comments
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Closeup:
Looks nicer than the last one, lets see how it reacts to the land/sea change
they will...you're annoying poof!
Looks just south of west to me.
hot towers
impressive
Yes, that is well-known. Ike was a ridiculously huge storm (hurricane wind radius larger than many system's tropical storm radius) with the pressure of at least a cat 3, possibly a 4. And a surge in that range as well. Alex looks a lot like Ike in many ways, including pressure that does not correlate with wind the way an "average" system would. But what kind of surge will it produce?
browser?
I would have to serve myself something if that happens, haha! >:D
Well "these people" must not get it either.
AL, 01, 2010063000, , BEST, 0, 230N, 944W, 65, 973, HU,
i fear think ike ish....
A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.
I'm really tired of having to explain this each year. The data IS from the National Hurricane Center to the models, this has shown us what the next advisory is going to be each time Alex gained strength, weakened, or stayed the same and with every other storm the past few years.
Seriously I must eat a bit of crow. I thought for certain this thing was going further north, maybe Corpus Christi.
For the record I was the only answer that included the definition of Knot as a "nautical MPH" for Balto. I thought that was what she was asking for anyway.
I hope to GOD he isn't trying to bury himself down in the BOC, if he does, he's hanging around waiting for that next trough.
They will not issue a special advisory until recon does a NE quad pass.
Simple.
There is some. Not great, but a chance.
I find that you guys speak Spanish funny. XD
As you would think we speak English funny. LOL!
Just sayin :-/
Or.... did he forget to log in?
Then why doesn't the NHC change the post?
Exactly! They want to see what are the strongest winds before issuance.
Transmitted: 30th day of the month at 01:06Z
Date: June 30, 2010
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Storm Number: 01
Storm Name: Alex (flight in the North Atlantic basin)
Mission Number: 10
Observation Number: 21
INBOUND
01:06:30Z 22.617N 93.033W 842.5 mb
(~ 24.88 inHg) 1,471 meters
(~ 4,826 feet) 997.1 mb
(~ 29.44 inHg) - From 185° at 45 knots
(From the S at ~ 51.7 mph)
I've seen that some of the models are forecasting possible development off the Alabama coast this weekend. Since I live on the Alabama coast (Mobile), that kinda has me a little concerned. Hopefully nothing will form.
Haven't been that far east (Anahuac) in a year, since my grandmother's funeral. Tons of blue tarps still up everywhere. How is it now?
I have been hoping the NHC would re-evaluate how they assign category numbers to account for systems like Ike (or Katrina), where the storm behaved more like something a lot stronger than it officially was. Go look at what they have done with the Fujita Scale (which is no longer in use in the US, but was replaced with the Enhanced Fujita Scale).
FULL IMAGE
SOURCE
Rural..and Still in the throes of recovery
what dry air lol
http://www.ssd.noaa.gov/goes/flt/t1/wv-l.jpg
Its feeding information for the models to run off of on the next run, they only issue advisories at 2, 11, and 8 a.m or p.m unless there is a special change.
Or was there an JAVA/etc update that I haven't heard of?"
1461 ShenValleyFlyFish "browser?"
Mexicans say you speak Spanish funny and Britons say I speak English real funny.
LOL
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