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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2164. Drakoen
Models take 91L inland in 24 hours. That's the amount of time it has to do something.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
Quoting bajelayman2:


Okay, sorry too. I guess I was over-sensitive, just was a fan of Carradine, the Actor, so reacted thusly when I saw the frame and comment.

Sometimes writing comes across different than intent, so reader reacts differently to intent.

Take care.

I am actually a big fan too, my husband and I have watched the movies more times than I can count and I did not mean any disrespect in that manner.

I am mostly just a lurker (I really do not know much about weather other than what I have learned here the last year)
My apologies for the bad joke.
Returning to lurking....
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Quoting southfloridajunkie:
We have Atlantic Floater 3 (Invest) for wave off the coast of Florida.

Link


we on the blog were up to DATE on this one right this afternoon. I'm very proud of you guys!

sadly my F5 session will end soon, but tomorrow will come full force.
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What about El Niño, well thanks. Quiet season LOL!
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where do they think 91L is going? where at on the GLuf coast?
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Quoting Weather456:


we have 91L


what a day


we might also have 92L soon with the African wave...
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Quoting Weather456:


we have 91L


what a day


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
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91L is in a favorable upper enviroment with some anticyclonic flow. With SSTs near 30C, some slow development is possible



Member Since: July 24, 2005 Posts: 407 Comments: 19076
ironically it seems that the upper leveltrough is helping ana, wetting their environment ..
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2154. Drakoen
Quoting WeatherStudent:


Really? Damn, Drakoen, which ones? Dispiccable and dosage, right? I knew it. I apologies.


Word usage is in regards diction while syntax is in regards to sentence structure.
Member Since: October 28, 2006 Posts: 57 Comments: 30829
Quoting MississippiWx:


What makes me stop and wonder about all the Northerly-biased models is the fact that Bill is still racing just South of due West at a fairly low latitude. For him to go north of the island chain, he's going to have to put on the brakes and/or strengthen significantly. Still could very much see a turn to the north eventually, but not before giving the islands a pretty hard punch.

I totally agree with you.
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2151. Patrap
Quoting PanhandleChuck:



What are we looking at Pat?


Should be interesting to see how the Invest,GOM Screamer handles the Loop edy and DMAX.

Member Since: July 3, 2005 Posts: 428 Comments: 129844
Quoting CJ5:


Yep, that is basic stuff I usually do too, as should everyone but like most on here I posted before I actually knew the facts..lol
Happens to the best of us. No worries.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
2149. Grothar
Quoting WeatherStudent:


Evening Mr. W,

Sir, please, for the love of God, you do not have to justify your professional meteorological credentials to the dispeccable redundant needs of absolutely no one on here. You demonstrate those impeccable credentials of yours on here, every single day with your exceptional tropical outlooks. Unfortunately speaking, the predominant conundrum here appears to be that they're are certain bloggers that are very much jealous and envious of your skills, and that would basically have to be about it. That was my two cents worth right there. Talk about a sour dousage of inferiority and superiority complex, geeze. :)
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.
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Quoting Tazmanian:
nic now we got Ana bill and may be 92L did i for get any thing


The wave that just exited africa.
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2147. JLPR
Quoting serialteg:


yo estoy READY pa surfear! woooooooooooooo

y la planta electrica coming soon!

manana brego el problema del agua... ya hice comprita en walmart... increible como la gente pichea a estas cosas y se pone a comprar popcorn, celulares jeje


jeje xD
asi somos =P
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Quoting nrtiwlnvragn:
AL 91 2009081600 BEST 0 260N 830W 25 0 DB
wow
Quoting hurrizone:
I THINK BOTH SYSTEMS WILL CONTINUE TO THE WEST MORE TIME THAN THE MODELS PREDICTS WITH A REAL IMPACT IN THE EASTERN CARIBBEAN.ALSO I THINK BOTH ARE GOING TO AFFECT VIRTUALLY THE SAME AREAS WITH TWO DAYS DIFFERENCE.I AM PREPARE FOR THIS SCENARIO.


i am not yet fully prepared, but doing what i can
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if Ana or Bill isn't your cup o' tea, I counted 3 more waves of disturbed weather heading to be off Africa, one emerging right now. Back to the fishcasters and wishcasters on channel 68.
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Quoting nrtiwlnvragn:
AL 91 2009081600 BEST 0 260N 830W 25 0 DB


we have 91L


what a day
Member Since: July 24, 2005 Posts: 407 Comments: 19076
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.
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Quoting nishinigami:


My apologies if I offended you. For many of us on here we watch the storms, but hope for them to turn and go away and not actually bother anyone. I meant no disrespect with my comment.


Okay, sorry too. I guess I was over-sensitive, just was a fan of Carradine, the Actor, so reacted thusly when I saw the frame and comment.

Sometimes writing comes across different than intent, so reader reacts differently to intent.

Take care.
Member Since: Posts: Comments:
Quoting Weather456:
The black hole at the equator is causing Bill to move more south

possible
2139. xoverau
Just wanted to say (as one of those people who seldom posts but avidly follows this blog) I use the advice, graphics, and discussion here to add authority to my warnings to family and friends who live in FL and along the coasts. I appreciate the on-topic, informed posts more and more the closer storms get to land. I second everyone's motion to calm the hysteria and focus on data; it does influence what folks do.
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Quoting StormW:


Thanks Cat! Good to hear from ya!

Hey Storm,
I'm fairly new to the site and always look forward to your post and read them regularly. Thanks for all the updates!!
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nic now we got Ana bill and may be 92L did i for get any thing
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
we could see something developing fast in the gom gulf coast residents keep up to date this could be a real kicker , lots of moisture,sst and little shear perfect conditions for a u know whatmmmmmm! be safe all
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Someone at the NHC once said "Hurricanes are like bananas, they come in bunches" I think it Franklin but I'm not sure.
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You know what's bad with wishing it doesn't hit you? That means it will hit someone else.
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GOM growing her own... how about that...
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AL 91 2009081600 BEST 0 260N 830W 25 0 DB
Member Since: September 23, 2005 Posts: 15 Comments: 11343
some gusts of up to 45 mph were reported somewhere in FL. (can't remember, probably in the tampa area)
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We have Atlantic Floater 3 (Invest) for wave off the coast of Florida.

Link
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Quoting Patrap:



What are we looking at Pat?
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Quoting stormfanpr:
Good evening everyone. Looks like this is going to be a very intense week for us here in Puerto Rico.


yo estoy READY pa surfear! woooooooooooooo

y la planta electrica coming soon!

manana brego el problema del agua... ya hice comprita en walmart... increible como la gente pichea a estas cosas y se pone a comprar popcorn, celulares jeje
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The black hole at the equator is causing Bill to move more south

Member Since: July 24, 2005 Posts: 407 Comments: 19076
2124. CJ5
Quoting stormwatcherCI:
I always check previous coordinates on the storms archive usually 12 hours before the previous. I checked 5am and 5 pm for that.


Yep, that is basic stuff I usually do too, as should everyone but like most on here I posted before I actually knew the facts..lol
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Well I guess it explains all the rain in Florida today.
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Quoting Barbados:


Hi Baje and Stormdude. I guess our met people may mention something on Monday if we are lucky. Does our multi million dollar radar work yet?



Hi Barbados, the Met mentioned Bill this evening, I think also that would be in the vicinity in a few days. Not too much else on expectations.

I have not a clue about the radar, I am just an amateur, with no official connections.

But, keep your eye on Bill.

Hopefully, the models are right and he will go to our North, but we need to watch closely.

I will check again first thing tomorrow morning.

Take care.
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2120. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129844
Quoting whipster:


Link?

Invest
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Quoting Barbados:


Hi Baje and Stormdude. I guess our met people may mention something on Monday if we are lucky. Does our multi million dollar radar work yet?



It's working, but you can't access it from the internet yet....
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Wont be surprising to see 92L tomorrow.
(note, we already had 91L, some reason the Navy made 91L ex-TD2)
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I THINK BOTH SYSTEMS WILL CONTINUE TO THE WEST MORE TIME THAN THE MODELS PREDICTS WITH A REAL IMPACT IN THE EASTERN CARIBBEAN.ALSO I THINK BOTH ARE GOING TO AFFECT VIRTUALLY THE SAME AREAS WITH TWO DAYS DIFFERENCE.I AM PREPARE FOR THIS SCENARIO.
Member Since: Posts: Comments:
Quoting bajelayman2:


Sorry, I do not think that is in much good taste.


My apologies if I offended you. For many of us on here we watch the storms, but hope for them to turn and go away and not actually bother anyone. I meant no disrespect with my comment.
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has the power to steal attention away from Bill and Ana

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

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

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