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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2364. Skyepony (Mod)
Can see the shear on Ana, south just outside her.

Level Geo. Height Air Temp. Dew Point Wind Direction Wind Speed
1012mb (29.88 inHg) Sea Level (Surface) 28.6°C (83.5°F) Approximately 23°C (73°F) 215° (from the SW) 5 knots (6 mph)
1000mb 108m (354 ft) 27.6°C (81.7°F) Approximately 23°C (73°F) 235° (from the SW) 6 knots (7 mph)
925mb 794m (2,605 ft) 21.4°C (70.5°F) 19.3°C (66.7°F) 240° (from the WSW) 7 knots (8 mph)
850mb 1,524m (5,000 ft) 18.0°C (64.4°F) Approximately 13°C (55°F) 225° (from the SW) 9 knots (10 mph)
700mb 3,165m (10,384 ft) 9.8°C (49.6°F) Approximately -4°C (25°F) 85° (from the E) 18 knots (21 mph)
500mb 5,880m (19,291 ft) -4.1°C (24.6°F) Approximately -22°C (-8°F) 30° (from the NNE) 8 knots (9 mph)
400mb 7,600m (24,934 ft) -14.9°C (5.2°F) Approximately -36°C (-33°F) 45° (from the NE) 9 knots (10 mph)
300mb 9,710m (31,857 ft) -30.9°C (-23.6°F) Approximately -51°C (-60°F) 95° (from the E) 11 knots (13 mph)
250mb 10,980m (36,024 ft) -40.9°C (-41.6°F) Approximately -57°C (-71°F) 135° (from the SE) 18 knots (21 mph)
200mb 12,460m (40,879 ft) -53.1°C (-63.6°F) Approximately -70°C (-94°F) 100° (from the E) 27 knots (31 mph)
150mb 14,260m (46,785 ft) -65.3°C (-85.5°F) Reading usually unavailable when air temperature is below -40°C (-40°F) 130° (from the SE) 24 knots (28 mph)

Hope they fly 91L soon, it's moved enough away from shore I don't have the surface obs I've had for 2 days.

Lightning here is shakin the house..

Member Since: August 10, 2005 Posts: 174 Comments: 38195
2311. Skyepony 1:17 AM GMT on August 16, 2009
Quoting thelmores:


You have to look at it in relation to its surrounding pressure as well...... pressure gradient. Not just the actual pressure.

So while 1013mb may not be impressive, it may be a little more quantitatively than normal.

I bet Drak will be impressed! quantitatively! LOL



thelmores is right. It's imbeded in an area of 1017+ mb...pressure gradient makes the wind.
----------

i have to agree. its just like tropical systems in the pacific. because the pacific has a lower ambient (sp?) pressure, a TC with a pressure of 1000 mb will most likely be weaker than a TC in the atlantic with a 1000 mb pressure. the reason is because the atlantic overall has higher initial pressures.
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2362. IKE
Quoting WindynEYW:
91l blew through key west earlier with lots of thunder/lightning/rain, we had a man struck while trimming a tree during the worst of it, but we were able to resuscitate him, never play with metal poles or saws on aluminum ladders in a storm...


So much for the downcasts on here about it....glad the man is alive.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting TampaMishy:
Is Drak and WS the same person?
nope ws is JFV
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Quoting Weather456:


they're gonna shift, but as to how much, still dont know


Are you making any preps?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Within reason how strong can 91L get? I know anything is possible and all that stuff.... but what is the best educated guess based on odds and stats? How strong will it get?
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Quoting IMA:

They say that about me all the time, but my name is spelled "Ann" & I hate being called Ana! :) Sorry, couldn't resist. I've been here all day and have been soooo quiet & good - knew it couldn't last!


it's good to be persistent in life .. as I say .. if life is not smiles .. you have to tickle.
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Quoting PcolaDan:


Give it a rest already.


If this bickering continues, I may want to become a volcanologist.
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Quoting leftovers:
very nasty storms seem to be moving on shore east central florida melb. radar shows it red
yep, they are here...lots of heavy rain, thunder and lightening!
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2355. jdjnola
Quoting washingaway:
91L may be the best thing that could happen for the gulf coast right now, maybe it can reduce the water temps in case Ana or Bill come a calling.


Unfortunately the loop current eddy can resupply warm waters pretty quickly.
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Quoting TampaMishy:
Is Drak and WS the same person?


Several believe they are...but who knows.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
91l blew through key west earlier with lots of thunder/lightning/rain, we had a man struck while trimming a tree during the worst of it, but we were able to resuscitate him, never play with metal poles or saws on aluminum ladders in a storm...
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Quoting CaneWarning:


What does this mean for the overall track?


they're gonna shift, but as to how much, still dont know
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting jpsb:
Yea, right.
There is so much energy available in the gulf something was bound to pop.Maybe less sarcasm?
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Quoting jaevortex:



hi i'm not too sure on what stormW training is.. but here's what i see from his signing(credentials) after posting his synopsis for the tropics


T. F. "STORM" WALSH III
GMCS, USCG (ret)
METEOROLOGIST/TROPICAL FORECASTER
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER


is it cause he doesn't have a phd? is that why you're saying he's not fully trained? i just have one more question.. are all mets phd holders? jw what your thoughts were..


From the American Meteorologist Society web site.

WHAT IS A METEOROLOGIST?

When we hear the word "meteorologist," we often think of the person on the television screen who tells us about tomorrow's high and low temperatures and precipitation. Many radio and television weathercasters are professional meteorologists, but others are reporters who are passing on information provided by the National Weather Service or private weather forecasters. The American Meteorological Society defines a meteorologist as a person with specialized education "who uses scientific principles to explain, understand, observe, or forecast the earth's atmospheric phenomena and/or how the atmosphere affects the earth and life on the planet." This education usually (my emphasis) includes a bachelor's or higher degree from a college or university. Many meteorologists have degrees in physics, chemistry, mathematics, and other fields. The broader term "atmospheric science" often is used to describe the combination of meteorology and other branches of physical science that are involved in studying the atmosphere.
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Is Drak and WS the same person?
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2348. IKE
Quoting nrtiwlnvragn:


He had one of his "special" weather statements. Said he would have more info into his office at 2 AM. Cropduster flight?


LOL!

What did his update say? Batten down the hatches?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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When does High School start?
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2345. IKE
Quoting HurricaneKyle:
Actually TampaSpin has called it for a while now.

91L was that tropical wave we've been watching since it got a 'yellow' near by where Bill is a week or so back.


True...forgot about TampaSpin...add him to the list....


99.9% chance this invest crosses land....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Anyone else thinking that dry air is going to wreak havoc on Ana?
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Quoting Weather456:
Bill continues WSW or 260

AL, 03, 2009081506, , BEST, 0, 118N, 320W
AL, 03, 2009081512, , BEST, 0, 115N, 333W
AL, 03, 2009081518, , BEST, 0, 113N, 345W
AL, 03, 2009081600, , BEST, 0, 112N, 359W


What does this mean for the overall track?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting IKE:


stormno has been talking about it for a couple of days. He said he would update tonight. Haven't seen anything from him unless I missed it....

Bastardi has been talking about it.


He had one of his "special" weather statements. Said he would have more info into his office at 2 AM. Cropduster flight?
Member Since: September 23, 2005 Posts: 14 Comments: 11215
Quoting tennisgirl08:
Any thoughts on the 11pm advisories?

My take:

1) orange or red code for invest 91

2) more south on the models for Bill

3) no change for Ana
All or any of the above.
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2340. Michfan
Quoting jaevortex:



hi i'm not too sure on what stormW training is.. but here's what i see from his signing(credentials) after posting his synopsis for the tropics


T. F. "STORM" WALSH III
GMCS, USCG (ret)
METEOROLOGIST/TROPICAL FORECASTER
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER


is it cause he doesn't have a phd? is that why you're saying he's not fully trained? i just have one more question.. are all mets phd holders? jw what your thoughts were..


By the standards set forth by the AMS he is a met.
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Im 45 miles east of you and we have one of the bands comming through now. Lots of thunder and rain but not to windy. Just gonna be a wet night.
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Any thoughts on the 11pm advisories?

My take:

1) orange or red code for invest 91

2) more south on the models for Bill

3) no change for Ana
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Bill continues WSW or 260

AL, 03, 2009081506, , BEST, 0, 118N, 320W
AL, 03, 2009081512, , BEST, 0, 115N, 333W
AL, 03, 2009081518, , BEST, 0, 113N, 345W
AL, 03, 2009081600, , BEST, 0, 112N, 359W
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting PanhandleChuck:


Can't remember who, but someone on the blog about 3 weeks ago predicted that during this time period. Wasn't a troll either


That would be me I predicted 8 storms in a 3 week period
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Looks as if the STORMNO, CAT, TOP..... weather center may have guessed this one! Lookout for some heavy duty CAPS laden posts to be forthcoming!
Member Since: September 1, 2007 Posts: 0 Comments: 1989
Quoting WeatherStudent:


Well, yes! But that doesn't mean that I can't be college educated, now doesn't 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.



hi i'm not too sure on what stormW training is.. but here's what i see from his signing(credentials) after posting his synopsis for the tropics


T. F. "STORM" WALSH III
GMCS, USCG (ret)
METEOROLOGIST/TROPICAL FORECASTER
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER


is it cause he doesn't have a phd? is that why you're saying he's not fully trained? i just have one more question.. are all mets phd holders? jw what your thoughts were..
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I think 91L is nothing to worry about. It may not even have enough time to make tropical depression status.
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Actually TampaSpin has called it for a while now.

91L was that tropical wave we've been watching since it got a 'yellow' near by where Bill is a week or so back.
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I'm in Tampa - 91L doesn't seem to be doing anything to my weather.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting WeatherStudent:


Well, yes! But that doesn't mean that I can't be college educated, now doesn't it? :)
College educated thug....That's one for the books. LOL
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2327. IMA
Quoting farhaonhebrew:
amazing how that Ana still exceeds the unfavorable conditions..

They say that about me all the time, but my name is spelled "Ann" & I hate being called Ana! :) Sorry, couldn't resist. I've been here all day and have been soooo quiet & good - knew it couldn't last!
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Maybe this will work...

Link
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Quoting tropics21:
what i meant to post was being of military background I know many Military Meteorologists that are registered with the AMS and some of the latest satellite floaters are Military yes Some have learned their trade in the Military but are just as qualified as college grad mets. also some of the so called High Tech methods are developed by the Military and passed down to the Colleges
I bet 50 % of this site has an average age of below 20 years old. Me? I'll take the opinion of a seasoned Vet anytime to compare Ananlsis over an Intern or wannabe. so I'll just sit back and lurk watching and laughing at the video game going on keeping my analysis to myself
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2324. IKE
Quoting MississippiWx:
Blah, I think we could be in for a show tonight from 91L. BTW, Ike...You called this one yesterday. I know it hasn't formed yet, but you certainly warned everyone of the possibility. Nice pick up!


stormno has been talking about it for a couple of days. He said he would update tonight. Haven't seen anything from him unless I missed it....

Bastardi has been talking about it.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Zoomiami... mail. Thanks in advance.
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Quoting IKE:


Moving at 300 degrees is WNW...moving at near 16 mph...looks like it's got 36 hours +/- before landfall.

Could have Claudette in the GOM....a little wearing and tearing on GOM folks...


I think this could be Claudette, too. Seems to be moving more westerly than northerly. I am wondering, though, what is steering it? Could it hit TX/LA border, or MS/AL? Either way, TX really needs the rain the most.
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Thoughts on the direction of 91L?
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Quoting weathercrazy40:
anyone call tell us up here in new england how much we should keep bill in the backs of our minds for later next week


just keep an eye out for now.
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Guess picture didn't work..try this link. Does it (Bill) look to be going a little south to you. It said it was going WSW.

Link
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I'm NE of any COC with 91L, I'm getting Winds to the N-NE, light.
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wow just got back from the beach and boy she's blown up in the GOM...looks like a tight spin also...any new news about it yet?
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The pressure is high across the whole GOM. That doesn't mean it can't develop. You can have a hurricane with abnormally high pressure. Its nature...
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Blah, I think we could be in for a show tonight from 91L. BTW, Ike...You called this one yesterday. I know it hasn't formed yet, but you certainly warned everyone of the possibility. Nice pick up!
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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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