Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 4:17 PM GMT on August 15, 2009

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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

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Go outside to walk the dog and come back in to a new invest, what's next.... Oh, yeah - African wave!!!
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Night all.
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While Wilma started over Jamaica...it rapidly intensified in the same general area to make landfall as a major huricane. I doubt many people anticipated that since it had already made landfall in cancun. No one thought that the area between cancun and SWFL would be enough to allow for a major hurricane second landfall. There are others that have surprised even the best mets at how quickly they can intensify in these waters.
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Back to matters

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting truecajun:


yes bill looks good there


Wow you look so cute in the pic! :) haha!
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2209. Skyepony (Mod)
Gulf streamer is a NOAA invest & has floater on it.
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Quoting CosmicEvents:

You're right. He's the quasi-met I mentioned. He knows his stuff allright...but fully trained...nope.
.
He's paid(I guess, which would make him a professional) by the USCG(my thoughts with the troops land and sea), but he's not formally trained as far as I know. I have the same definition as you for what constitutes a fully trained met.
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So Drakeon is now our English professor as well?
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AL 91 2009081518 BEST 0 249N 818W 25 1014 DB
AL 91 2009081600 BEST 0 259N 831W 25 1013 DB
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2204. 996tt
Quoting Drakoen:
\

The way you use your commas. When and when to.


This really isn't the place for English lessons . . . Kind of like me acting like a met too . . . Let it go and enjoy life. Have a great evening you guys.
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.35kts-1004mb-112N-359W.95pc.jpg | Bill .35kts-1004mb-144N-507W.100pc.jpg | ANA From the Navy site
Member Since: October 9, 2008 Posts: 0 Comments: 8242
2202. JLPR
Quoting farhaonhebrew:


.. if the misinformation is going to be the agenda on Monday


xD Im going to pull a chair and sit inside a supermarket on Monday morning xD
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2201. IKE
Quoting nrtiwlnvragn:
AL 91 2009081600 BEST 0 260N 830W 25 0 DB


I figured it might get an invest.
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Quoting clwstmchasr:
2175. Tazmanian 8:49 PM EDT on August 15, 2009
i think 91L will make land fall somm where in TX


Taz, it's heading somewhere between the Western FL Panhandle and New Orleans.
i agree!!
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2199. jipmg
eh idk what im looking at, but looks like the LLC of TS ana has jogged NW a tiny bit, and BILL's center may be further south than the NHC estimated
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You can see 91L here

Link
Quoting stormfanpr:
Good evening everyone. Looks like this is going to be a very intense week for us here in Puerto Rico.


.. if the misinformation is going to be the agenda on Monday
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Quoting WeatherStudent:


Really? I see, are you saying that I committed a grammatical fragment, runoff, incomplete sentence, or what, Drak? Please further elaborate in regards to what you just meant by that? Because at first glance I thought that you were referring to the mispelling of certain terminologies.
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2193. Drakoen
Quoting WeatherStudent:


Really? I see, are you saying that I committed a grammatical fragment, runoff, incomplete sentence, or what, Drak? Please further elaborate in regards to what you just meant by that? Because at first glance I thought that you were referring to the mispell of certain terminologies.
\

The way you use your commas. When and when not to.
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Quoting Drakoen:
It's headed for the panhandle region.

crap
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Good point Rainy Eyes. I'm in Lehigh Acres!

FL could very well be quite soggy in a couple weeks.

What was that crazy lil storm that rapidly intensified at the beginning of season, was it last year or 2007 that hit SETX? Anyone remember off the top of their head. I suppose I could look it up. Not at home though so my bookmarks aren't available.
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By the way, I meant universal 'English' word for a disruptive blogger.
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2188. Skyepony (Mod)
Quoting Weather456:
proximity to land is the main problem


I was amazed how it tried over the spine of Cuba.
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Quoting bajelayman2:


A 'TROLL' is the universal internet language for someone coming onto a blog purely to make trouble, disrupt the blog.

Sometimes we may misinterpret intent and then think a person is a troll, but be mistaken.

Generally, it is fairly clear after a while, whether the person is merely being disruptive.



some regulars
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Weather456:


look at the post before yours. Forgive me but I will get back to you with where it is going. I have not been paying much attention but noticing something may try to get going.


Yeah, this one kind of came out of nowhere.
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Any updates on this interest in the GOM? Is it doing anything if so, where is it projected to go?
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CC TX here, we could use a soaker TD/TS

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Quoting Grothar:
Well said. Drakoen has been quite helpful to me as has Weather456 and a few others. I find your comments entertaining, although others may disagree. I find it admirable that someone has the passion to spend time and share information as many people on this blog do. It should be fun and informative. Don't let anyone make fun of your English. I do not want to make this blog too long, so I shall enter another later with some questions I have. Since English is not my first language what is the meaning of a TROLL. It appears to be used as a condescending remark.


A 'TROLL' is the universal internet language for someone coming onto a blog purely to make trouble, disrupt the blog.

Sometimes we may misinterpret intent and then think a person is a troll, but be mistaken.

Generally, it is fairly clear after a while, whether the person is merely being disruptive.
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2180. Drakoen
It's headed for the panhandle region.
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2179. Skyepony (Mod)
ULL is moving away from the gulf sreamer pretty quick.
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proximity to land is the main problem
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting hurricane23:
As bill intensifys at a pretty good clip during the next day or two theres a pretty decent shot it will feel the weakness sooner rather the later.Hopefully sometime next week the gulfstream jet should begin to fly to get a much better idea how strong that ridge is.Latest quikscat on bill was pretty impressive.


yes bill looks good there
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i think 91L will make land fall somm where in TX
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Quoting southfloridajunkie:
We have Atlantic Floater 3 (Invest) for wave off the coast of Florida.

Link



At this rate we may use-up all the Atlantic floaters.
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2173. Grothar
Here is my question. I looked at the NOAA vapor map and only see a large Low NE of the Bahamas. Can someone tell me what would cause the turn of Bill so rapidly to the North as is being displayed in the Ensemble models?

P.S. Hi Taz
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2172. Drakoen
Quoting canesrule1:
Can u give me the models, tahnks


Just look at the dynamic models
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Thanks... I just wasn't sure why an image of ohio and pennsylvania were up
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Quoting tennisgirl08:


456...would really like your opinion of this invest. I looked at the latest radar loops and it looks impressive and to have a swirl. are you surprised by the markings as an invest this early and could this be a TD? guess it will run out of time before becoming anything significant, but the temps in the GOMEX are so warm right now. thanks in advance


look at the post before yours. Forgive me but I will get back to you with where it is going. I have not been paying much attention but noticing something may try to get going.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Drakoen:
Models take 91L inland in 24 hours. That's the amount of time it has to do something.
Can u give me the models, tahnks
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Quoting homegirl:
Proximity to land is the only thing prohibiting development of the GOM blob, now an AOI and might soon be 91L?

Latest CIMSS shows an anticyclone forming, low shear, warm SSTs, closed low (west winds reported from bouys)

Not much time for this to organize, but the panhandle might want to keep an eye on it. Definitely going to be a rainmaker for FL, but it's moving quickly so flooding shouldn't be an issue.


I am not worried about the moisture out of the invest that is sitting over me right now...it really hasn't rained all that much considering what we get in any typical rainy season thunderstorm (I am in Cape Coral) BUT I am worried about already being wet from this, our rainy season pattern then getting a potential one-two punch from Ana and Bill. That may not happen, but if it does, the grounds may not be able to handle it.
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Quoting tennisgirl08:


456...would really like your opinion of this invest. I looked at the latest radar loops and it looks impressive and to have a swirl. are you surprised by the markings as an invest this early and could this be a TD? guess it will run out of time before becoming anything significant, but the temps in the GOMEX are so warm right now. thanks in advance


More than warm HOT! 90-95 degrees for SST's. It will probably become a weak TS Claudette before it makes landfall.
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Quoting Weather456:
91L is in a favorable upper enviroment with some anticyclonic flow. With SSTs near 30C, some slow development is possible






456 am looking for word too what the mode runs say about 91L
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2164. Drakoen
Models take 91L inland in 24 hours. That's the amount of time it has to do something.
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About JeffMasters

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