African wave 99L may develop; Felicia threatens Hawaii; record rains from Morakot
A strong tropical wave with a high amount of spin moved off the coast of Africa yesterday, and has a good chance of becoming the first named storm of the 2009 Atlantic hurricane season. The wave was designated 99L by NHC Sunday morning. Wind shear is moderate, about 10 knots, and sea surface temperatures are moderately warm, about 27 - 28°C. There is a large area of dry air to 99L's north, but this is not currently interfering with the storm's organization. This morning's QuikSCAT pass showed a nearly closed surface circulation, stretched out along two axes. The storm can now be classified as tropical depression using the satellite-based Dvorak classification technique, but the surface circulation will have to show better definition before 99L can be classified as a tropical depression. Top winds were in the 20 - 30 mph range, as estimated by QuikSCAT and the Dvorak satellite estimates.
Figure 2. Visible satellite image of disturbance 99L.
Wind shear is expected to be low, 5 - 10 knots, tonight through Tuesday. SSTs will remain relatively constant at 27°C, so conditions favor development. NHC has given 99L a moderate (30 - 50% chance) of developing into a tropical depression by Tuesday morning, which is a reasonable forecast. The UKMET, GFS, and NOGAPS models all develop 99L into a tropical depression 1 - 4 days from now. The dry air of the Saharan Air Layer may become a problem for 99L 2 -4 days from now, as the storm moves slightly north of due west. It is too early to say if 99L will recurve north of the Lesser Antilles Islands or not, since it will be at least 6 days before the storm makes it that far.
The GFS model predicts development of a new tropical wave coming off the coast of Africa about 6 - 7 days from now.
Felicia weakens to a tropical storm, still a threat to Hawaii
Tropical Storm Felicia has weakened steadily over the past 24 hours, thanks to cool sea surface temperatures and increasing shear. Recent satellite imagery shows that wind shear is beginning to affect the storm, with strong upper-level winds from the west pushing the storm's heavy thunderstorm activity all to the east side of the center.
Figure 2. History of hurricane activity over Hawaii since 1950. Hawaii islands have been hit by only 9 tropical cyclones of tropical depression or greater strength, with 4 others passing withing 75 miles of an island. Image credit: NOAA Coastal Services Center.
Sea surface temperatures (SSTs) under Felicia are 25°C, well below the 26°C threshold typically needed to sustain a hurricane. SSTs will slowly increase to 26°C by the time the storm reaches Hawaii, though. Wind shear has increased to a moderate to high 20 knots, and is expected to increase further to 30 knots by Monday morning. The high shear combined with the cool SSTs should reduce Felicia to tropical depression strength by the time the center reaches the Hawaiian Islands Monday night. The wind speed probabilities forecast shows about a 40% chance Felicia will still be a weak tropical storm when it moves through the islands Monday night, and 40% chance it will be a tropical depression. If Felicia does hold together that long, it would be only the tenth tropical cyclone of tropical depression or higher strength to affect the islands since 1950 (Figure 1). Large swells from Felicia are already affecting the Big Island, and a high surf warning has been posted for the Big Island. Felicia or its remnants should bring heavy rain, flash flooding, and mud slides to the islands beginning Monday morning, and a Flash Flood Watch has been posted for most of the islands.
Typhoon Morakot hits China
Typhoon Morakot hit China this morning as a tropical storm, lashing the mainland with very heavy rain. Yesterday, Morakot hit Taiwan, dumping up to 80 inches of rain on the island over a 2-day period, according to news reports. The world 2-day rainfall record is 98.42", set at Reunion Island on March 15 - 17, 1952, so the Typhoon Morakot 2-day totals are some of the highest ever measured in the world. The highest 1-day rainfall total ever recorded on Taiwan occurred Saturday at Weiliao Mountain in Pingtung County, which recorded 1.403 meters (4.6 feet or 55 inches) or rain. Nine the ten highest one-day rainfall amounts in Taiwanese history were reached on Saturday, according to the Central Weather Bureau. Three are dead and 31 people missing on the island, and Morakot also killed 23 people in the Philippines.
I'll have an update on Monday.
Jeff Masters
Reader Comments
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And very little rain in West Bay over the past week...except for a heavy 10 minute shower one of the days.
Reading back it looks like thing are getting a little crazy. lol
AGREED!! (ps. Anna only has 1 n (Ana))
Evening StormW
All's well it seems. Nothing on the horizon as a threat.
Ah Yes
Correct. The disturbance will remain somewhat on the diurnal side until it develops a better defined and stronger circulation center.
Lol, the ensembles are better than the models.
WHXX01 KWBC 100036
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0036 UTC MON AUG 10 2009
DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.
ATLANTIC OBJECTIVE AIDS FOR
DISTURBANCE INVEST (AL992009) 20090810 0000 UTC
...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090810 0000 090810 1200 090811 0000 090811 1200
LAT LON LAT LON LAT LON LAT LON
BAMS 14.4N 23.2W 15.4N 26.2W 16.2N 29.1W 16.7N 31.8W
BAMD 14.4N 23.2W 15.4N 24.9W 16.6N 26.5W 17.8N 28.0W
BAMM 14.4N 23.2W 15.5N 25.7W 16.6N 28.0W 17.5N 30.2W
LBAR 14.4N 23.2W 15.6N 25.2W 17.1N 27.0W 18.8N 28.4W
SHIP 25KTS 29KTS 33KTS 37KTS
DSHP 25KTS 29KTS 33KTS 37KTS
...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090812 0000 090813 0000 090814 0000 090815 0000
LAT LON LAT LON LAT LON LAT LON
BAMS 16.8N 34.1W 17.1N 38.7W 18.7N 43.3W 22.1N 48.2W
BAMD 19.1N 29.5W 21.8N 32.1W 23.4N 32.6W 22.1N 32.7W
BAMM 18.4N 32.2W 20.4N 36.7W 22.7N 41.3W 25.8N 44.4W
LBAR 20.6N 29.4W 25.2N 31.4W 27.7N 34.2W 27.8N 35.3W
SHIP 40KTS 44KTS 43KTS 36KTS
DSHP 40KTS 44KTS 43KTS 36KTS
...INITIAL CONDITIONS...
LATCUR = 14.4N LONCUR = 23.2W DIRCUR = 295DEG SPDCUR = 13KT
LATM12 = 13.4N LONM12 = 21.0W DIRM12 = 293DEG SPDM12 = 16KT
LATM24 = 12.3N LONM24 = 18.1W
WNDCUR = 25KT RMAXWD = 30NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1010MB OUTRAD = 130NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
$$
NNNN
Bravo
Don't call it home please we don't need any type of TC this year here in Puerto Rico. We are really strugle with the swime flu and economics issue to recieve an unwelcome visit this summer. So call for a fish!!
Must have held the "N" key down too long LOL
Hilarious, can't stop LMAO
yea that is what I ment to say...wife was talking to me while I was typing so I obviously had no idea what I was typing.
I was bored so I made a compound-complex sentence.
And the CMC and the UKMET and the ECMWF.
and the ensembles but NOGAPS is the first to dive down there. It has only been 24 hours just wait. You will see all of them start to creep their way southward over the next two days and match the ensembles.
CMC....UKM
Very little I am afraid to say. For July only 2.05 inches at my home and so far for August only .30
Every day the temps are in the mid to high 90's with a heat index of close to 115.
To play in this heat requires constant fluid intake and that means water LOL
Hmmm...interesting
I see that nothings changed.
Im not talking about 99L.
The steering currents have not changed much, and still expect this system to move generally westward. The reason why the GFS expects to recurve out to sea, is because a shortwave trough is expected to amplify over the mid-Atlantic by about Friday. This may be enough to split the Atlantic subtropical ridge, and provide a weakness that would induce poleward movement. Most of the models do seem to agree with the Atlantic ridge-split scenario, but think that 99L will bypass it. The GFS moves it anomalously northward despite under the influence of the ridge, despite the ridge split. Thus, the GFS' poleward bias seems to be the reason why it is expecting this outcome. All-in-all, I am giving this a 30% chance of curving out to sea.
Well if you are a met I hope your abilities to forecast and there are many that can long range forecast the synoptic pattern. Even if you cant it is fun to try and learn from it if you are right or wrong.
what is it with the "coincides with a maximum observed in the total
precipitable water imagery" that they're adding now to every nhc discussion wave?
I think you should have a meeting with Cantore... Make it in Canada though. (Like in the YUKON Territories!)
Its ridiculous. Watch, it'll blow up again and people will do a 180 again. Its not even a Depression yet and people are banking on all these long range models. No one, not even the guys at NHC know where this'll go.
Just answering the question. I do not get fired up over anything anyone says here. I just assumed it was a normal question so I gave a calm normal answer.
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