Ana and TD 3 take aim at the Lesser Antilles
Tropical Storm Ana was born this morning, when the remnants of Tropical Depression Two made a comeback and organized into the first tropical storm of the 2009 Atlantic hurricane season. Ana is the latest first named storm of the season since Hurricane Andrew got its name on August 17, 1992. The two storms have some similarities, as Andrew formed in the same part of the ocean, and also struggled in its early days with high wind shear and dry air. Let's hope the similarities end there.
Ana is struggling this afternoon. After an modest burst of heavy thunderstorm activity prompted NHC to upgrade Ana to a tropical storm early this morning, Ana has run into strong upper-level winds from the west that are creating high wind shear. This shear was not forecast, and it is not clear how long it will last. The shear has acted to drive dry air into the core of Ana, destroying almost all of Ana's heavy thunderstorms. The low-level center of the storm is now exposed to view, something that often foreshadows the death of a storm. It is possible the shear will destroy Ana, and several models (the GFS and ECMWF) forecast this may be the case. However, the shear forecast calls for shear to drop into the low range, 5 - 10 knots, tonight through Tuesday. If the shear does drop as forecast, Ana should be able to moisten the atmosphere around it sufficiently to protest itself from the dry Saharan air that surrounds it (Figure 1). SSTs are 27°C today, and will increase to 28°C by Sunday. By the time Ana moves into the Bahamas, total ocean heat content rises steeply (Figure 2), and rapid intensification of Ana is possible, if the shear and dry air haven't disrupted the storm. The intensity forecast models, for the most part, predict a steady intensification of Ana to the threshold of hurricane strength five days from now. The HWRF model is on the strong side, predicting a Category 2 hurricane. The GFDL predicts a weak tropical storm five days from now, but that is because the model has Ana passing over the rugged terrain of Hispaniola, something the other models do not predict. In summary, the intensity forecast for Ana has higher than usual uncertainty, and I give equal chances that the storm will be a hurricane--or non-existent--four days from now.
Figure 1. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the north of Tropical Depression Three. Image credit: NOAA/SSD
Tropical Depression Three forms, could be Bill later today
QuikSCAT data from this morning and satellite loops revealed that the tropical wave (90L) in the middle Atlantic has finally developed a well developed surface circulation and can be classified as Tropical Depression Three. Recent satellite imagery suggests that TD 3 may already be Tropical Storm Bill. Water vapor imagery (Figure 1) shows that TD 3's center consolidated a few hundred miles south of the dry air of the Saharan Air Layer (SAL). Thus, the storm should not be affected by dry air and dust as much as Ana has been. Ana may also act to moisten the atmosphere in front of TD 3, helping protect the storm from the SAL as it edges farther north over the the three days.
Figure 2. Heat content of the ocean, in kJ per square cm. Oceanic heat content steadily increases for Ana and TD 3 as they approach the Lesser Antilles Islands. Oceanic heat content levels of 90 kJ per square cm are frequently associated with rapid intensification of hurricanes. Image credit: University of Miami.
Wind shear is moderate, 15 knots, but is forecast to fall to 10 - 15 knots on days 2 - 5. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow TD 3 to intensify steadily, and I expect the storm will be at hurricane strength by Wednesday, when it will be near the northern Lesser Antilles Islands. Most of our reliable intensity models strengthen TD 3 into a hurricane by Wednesday. Oceanic heat content (Figure 2) increases sharply just before the islands, so TD 3 could be intensifying rapidly as it moves through or just north of the Lesser Antilles on Thursday. TD 3 consolidated farther south than expected, so the track models calling for a more northerly path were probably incorrect. In particular, the ECMWF model, which had TD 3 turning sharply northwestward and missing the Lesser Antilles Islands, was probably much too far to the north in this morning's 00Z run. TD 3 will probably pass very close to the northern Lesser Antilles islands on Wednesday and Thursday.
I'll have an update Sunday.
Jeff Masters
Reader Comments
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You're welcome.
Rains moving in now.....again.....
Welcome to the jungle. How long til the swell gets here?
Station SMKF1
Wind Direction (WDIR): W ( 260 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 19 kts
5-day plot - Wind Gust Wind Gust (GST): 21 kts
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 30.05 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): 0.02 in ( Rising )
5-day plot - Air Temperature Air Temperature (ATMP): 73.6 °F
5-day plot - Dew Point Dew Point (DEWP): 70.3 °F
5-day plot - Tide (above MLLW) Tide (above MLLW) (TIDE):
I agree..
pretty darn muggy and warm out too.. just hoping this blob doesn't form anything for you guys up north or in the gulf..
There are no Cat 5 building codes. If there were, buildings constructed to them would not be affordable to most people.
now THAT brings back memories
I was just going by what the NHC said. You may be right.
That blob needs to be 91L.
As K and Rita and Wilma All Showed in 2005,TCHP and upwelling dont alway's bring the Mixing one desires to see. This year were even warmer as 05.
Wind Direction (WDIR): SW ( 230 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 19 kts
5-day plot - Wind Gust Wind Gust (GST): 21 kts
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 30.04 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.02 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 75.4 °F
5-day plot - Dew Point Dew Point (DEWP): 69.1 °F
5-day plot - Tide (above MLLW) Tide (above MLLW) (TIDE): 0.85 ft
Yes, true...
But Category 5 hits are the maximum end of the scale, not the ONLY scale. You prepare yourself as best you can, even on the humblest of budgets, but intelligence.
I agree. Nothing to worry about now. Surface pressure are high. None of the computer models show development.
Thoughts
I don't want to have to deal with the noise and the Carbon emission.
I thought there was a front in the SO CONUS pushing south that might stall a storm in the GOM for a while without forward direction.
They weren't concerned about Humberto, either.
Many times the storms that are born in the GOM are not good-take Opal for example back in 95. Started in Bay of Campeche and made a beeline for Pensacola
All of that is possible. Still too early to tell the model really have been flip flopping on this trough.
listen, it doesn't matter what you say, if something is forming its forming, if something is dissiapting its dissipating, if people wishcast that doesnt mean all of a sudden the storms are going to form. If people down cast its the same thing.
Say what your eyes are seeing, and what reports are saying, dont say something is going to die or strengthen just because you want it to.
I'm actually always thinking about my Internet connection and riding it out with you guys on...
*aww* :D
Its the closest thing to home.
do the models show it moving WNW in the short term? Seems to be doing that right now
Wind Direction (WDIR): SSW ( 200 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 23 kts
5-day plot - Wind Gust Wind Gust (GST): 26 kts
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.99 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.04 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 77.5 °F
5-day plot - Water Temperature Water Temperature (WTMP): 86.2 °F
5-day plot - Salinity Salinity (SAL): 36.04 psu
And makes Ana look like a fart.
Ride it out with your family. We are just people behind computers that post everyday.
wait. so you like power, don't wanna lose it, but don't want a generator either?
Quoting Nolehead:
510. IKE 6:10 PM GMT on August 15, 2009
Quoting Bailey1777:
Any chance the blob in the GOM gets far enough West to give us some precip in Houston?
NHC says it's moving NW. That would put it coming in around Mobile/Pensacola.
lol..great let me get my red carpet out..
Welcome to the jungle. How long til the swell gets here?
hope this late afternoon or early dawn patrol!!!
Pcolasky...yeah i was working downtown p'cola took me 2 hours using every back road i knew to get me to my house on 9 mile...crazy!!!
I know you love me, man. Let it out. A little love won't hurt
I don't see anyone wish casting that blob. I do however see you getting ignored though :) -poof goes ws-
Yes. GFDL, HWRF, and the 3 BAM models show that.
Take a break, relax and realize the 12z models of today might not be the same as the 12z models of tomorrow.
Link
are you hogging all the rain today? I haven't had a drop at my house yet and don't want any!..lol
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