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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I live on a lake....up a hill....winds are exacerbated here because of a slight up-slope from the lake....
I road out a TS here before....house sits up off the ground....I'm not BS-ing....my house was shaking.
It was not fun.
AMOUNTS OF 10 INCHES ACROSS PORTIONS OF NORTH FLORIDA NEAR THE PATH
OF THE CENTER.
COASTAL STORM SURGE FLOODING OF 3 TO 5 FEET ABOVE NORMAL TIDE
LEVELS CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE CENTER
MAKES LANDFALL.
From the advisory for TD4.
Possibly the last few frames, but not really enough to tell, plus the center is a little bit more tricky to spot..
STRENGTHENING PRIOR TO LANDFALL BUT AFTER THE 12 HOUR 45 KT
FORECAST INTENSITY SHOWN BELOW IS LIKELY.
Yea, I wish i could see the look on their faces when they turn on the tv when getting their cup of coffee...WTH! a TD! *spills coffee*
I have so much to learn about this stuff...if anything on radar..my idea would be that its less organized..but i shalt agree with Ike that there is more red around the center..i probably think it has to look perfect to be a storm lol
NHC doesn't just yet on the site but hey anything can happen examples are Humberto 07 and Marco 08 (not a hurricane but a strong TS)
I think NHC had it at like 1% chance lol..not likely..
I wouldn't rule it out.
maybe?
There are others...TampaSpin.....
Channel 7 in Panama City hasn't even mentioned it....hello! Wake up. lol
Wow! LOL like a said earlier rude awakening. Maybe they should have some of that coffee dumped on them it isnt working fast enought hehe
Probably a 50-60 mph TS at landfall.
Coming in from our SSE may lessen it's affects...hopefully....
FOX 28 in Panama City...nothing...
but i knew when i went to bed we would have a td if not a ts this morning.. had to have a little sleep.....
so im sitting here working on my shopping list since this was my prep week.... watching ana and bill... and along comes td4 to celebrate the 40th aniv of camile..... yep thats monday....
The meteorologist is sleeping!..he must not be awaken..though id think someone is in the office..at least they could page him and tell him to get the heck out of bed..haha
TD 4 - is consolidating.
Its amazing that you go to bed at 22:00 BST, and get up at 10:41 BST - and this just decides to turn up.
LOL...
Buoy within 50 miles of the COC...not much...but it's WNW of the center....
Like I said they need the hot coffee spilt on them it isn't working by just drinking it LOL =D
Literally....
Long time lurker here. I'm in Mobile and I've checked all the local news stations this morning as well....nothing here either (with the exception of a mention to watch it on wkrg.com). It's amazing to me that this can happen. Hope it's very small and weak so that it doesn't catch anyone unprepared....the stores will be crazy today. Good thing we picked up some stuff yesterday just in the event that 'Gulf Blob' flared up!!
They won't mention it on the TV, its too late to evacuate people however there website is taking years to load:
http://www.wjhg.com/unclassified/769277.html
http://www.wjhg.com/
well heres whats feeding "Claudette"...
Sorry! I'll tell everyone I know to go to WalMart for their supplies today! lol! :)
http://www.fox28.com/global/Category.asp?c=162708
http://www.fox28.com/global/Story.asp?S=10754383
Those two have only just turned up on there website.
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