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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Could those rising pressures around td4 be the bermuda high building in? Forgive me if this a stupid question.:) won't be the first...
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Quoting WeatherGirl80:
Anyone here think that TS Ana, IF it makes it to the GOM, could regenerate once it hits those unobstructed warm SST's?


The models show enough structure to regenerate when in the GOM. Expect at least a strong tropical storm. She might get stronger though since it would pass over waters with the highest energy in the gulf. Ana is a fighter and I would worry if she remains intact and gets in there.
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4762. ITCZ
We've had alot of rain here in Havana, near Tallahassee in the last few days. I hope may-be-Claudette is kind to us....
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Quoting P451:


Nobody is messing with you guys. Navy site had Claudette. Weather456 saw it and posted it earlier as well if that would suit your interests.

It was listed as Claudette and then they changed it back to 04L. Why, I don't know.

Nobody is throwing the name out there without just cause. It was there.
I know it is annoying, several of us saw and reported it, I have a screen shot of it. (but decided it is not worth the effort to upload it.) Doesn't matter - it is TD4 for now, and a rose by another name is still a rose.
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4760. Dakster
Quoting tiggeriffic:
bounced in for just a few...tho i am no met... i have seen the so called wobble many times... especially over night...bill's center appears to be reforming...maybe even a tad to the south of the old one...if this is true then the models will shift again to the south closer to the UKMET...not that I trust the UKMET mind you...but radiational cooling does a lot to a forming storm...even big ones have eye wall replacement and they can reform in any direction of the original eye...no storm is a fish storm...last year a fish storm hit the UK...just cuz it isn't a US storm doesn't make it a fish storm by any means


Direction change or wobble wobble:

Link
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4759. Hhunter
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LOVELY breeze here in Tallahassee. It feels SO NICE outside- even with the humidity.
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4755. amd
for all the hype about TD4, radar clearly shows that showers not even 50 miles to the north of the system are not being pulled into TD4. This is what Dr. Lyons mentioned in his tropical update. These showers can not be wrapped into the system because the pressures are just too high.

Also, with Humberto, pressures were already low over the western gulf before the storm began to develop, and an eye like feature was noticed when Humberto was a 45 mph tropical storm.

TD4 will be nothing like Humberto. Humberto's pressure was at 986 mb right before landfall, while TD4's pressure is supposedly 1011 mb.
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4753. Hhunter
Quoting AussieStorm:

That's what some people in here will have you think, I on the other hand don't think that.


i think ana is scary because now it could slide into middle gulf...yikes

Bill east coast disaster movie potential
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The University of Tampa, Tampa, Florida (PWS)
Updated: 2 sec ago
79.8 °F
Clear
Humidity: 88%
Dew Point: 76 °F
Wind: 6.0 mphfrom the SE
Wind Gust: 18.0 mph
Pressure: 30.05 in (Steady)

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Mandy, the local mets just said for us to expect 3 - 4 inches... heck we got 3 1/2 inch here on Wednesday!
But as I said, prepare for the worst & hope for the best!
Alberto was an UGLY storm!
Quoting MandyFSU:
Foxx- I was thinking Alberto too. Doubt we get much of anything (I'll be happy with an inch of rain!) but we are under a flood watch and in Tallahassee the flood is as bad as the wind could be. If nothing else this is a "gentle" reminder that it is mid-August and nothing is off limits!
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Quoting CaneWarning:


I forget some people go to church these days. I don't know a single person who goes unless there is a wedding or funeral!
That speaks volumes.
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The sun is out in Tampa.
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Quoting HurricaneKyle:
So let me get this straight on the general feeling of the blog.

Ana is (again apparently) going to dissipate.

Bill was hype and is going out to sea.
(wasn't Ike called 'hype'?)

TD4/Claudette is going to be nothing more than a thunderstorm even though SST's are some of the hottest on Earth. Never know, think of Humberto.

:)

That's what some people in here will have you think, I on the other hand don't think that.
Member Since: September 30, 2007 Posts: 9 Comments: 15962
TD#4 is about 95 miles SSE of Apalachicola, this was an estimate by using the radar image. So I would say about 5 to 6 hours till landfall and that is with it going about 15 mph to the NNW.
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Hah, I thought pressure was too high for anything to develop in the gulf. When are people going to learn...never proclaim things as absolutes when dealing with weather
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4744. Hhunter


gulf is like bath water...pretty impressive blow up on dvorak
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There is some high level wv streaming N to meet Comet Ana...will it help...who knows.
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Quoting leftovers:
surfer storm beje


Gosh, y'all are so confident.

A little warning, remember it is early in the season yet and such early storms tend NOT to go too far North.
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I agree with that P451. The pressures certainly don't seem consistent with the rest of the factors of TD04. ???

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bounced in for just a few...tho i am no met... i have seen the so called wobble many times... especially over night...bill's center appears to be reforming...maybe even a tad to the south of the old one...if this is true then the models will shift again to the south closer to the UKMET...not that I trust the UKMET mind you...but radiational cooling does a lot to a forming storm...even big ones have eye wall replacement and they can reform in any direction of the original eye...no storm is a fish storm...last year a fish storm hit the UK...just cuz it isn't a US storm doesn't make it a fish storm by any means
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Quoting P451:


Nobody is messing with you guys. Navy site had Claudette. Weather456 saw it and posted it earlier as well if that would suit your interests.

It was listed as Claudette and then they changed it back to 04L. Why, I don't know.

Nobody is throwing the name out there without just cause. It was there.


Interesting, wonder why.
Member Since: August 10, 2009 Posts: 3 Comments: 672
4737. Walshy
Quoting sfla82:


LOL...No it wont....It would have to hit land first and right now the only land in danger is Bermuda.



It will still probably kill a few U.S citizens from rough waves on the east coast especially if it gets strong like its forcasted to do so. East coast to Bermuda needs to watch it as it passes north of the islands.
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great quikscat of "Bill" COC around 11.5N in my estimation.
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Quoting LightningCharmer:
Well if you're insinuating, I'm acting highbrow or mindful, well I reckon I'll take that as a compliment. Sorry your fishing was washed-out. Looks like clear skies for the Keys today.
Nope... My bad if that came across wrong, I was not reffering to you at all. Keyboards can be a bain on communications sometimes.
Clearer skies yep, mucked up water Yep.
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4732. Dakster
Quoting HurricaneKyle:
So let me get this straight on the general feeling of the blog.

Ana is (again apparently) going to dissipate.

Bill was hype and is going out to sea.
(wasn't Ike called 'hype'?)

TD4/Claudette is going to be nothing more than a thunderstorm even though SST's are some of the hottest on Earth. Never know, think of Humberto.

:)


I sense a hint of sarcasm in your post...

How about Ana is weakening, could regenerate or not.

Bill - Models say it is now gonna go North. Still have watch since it is a week or so more from CONUS.

TD4 - LOOKOUT... Run for the hulls. Whether it becomes a Cat1 or not, looks like alot of wind and rain regardless.

Prepare for the worst and hope for the best.
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4731. Hhunter
Bill is a scary player...potential to be the east coast disaster storm to which joe bastardi refers
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Quoting CaneWarning:


You've got it!


It appears so rofl.

We have absolutely no idea where Ana or Bill is going to go or the strength of all 3 systems.

I know though TD4/Claudette will make the second US landfall this year. (First amazingly went to TD Felicia on Hawaii)
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting hurricane23:


Dont think even the islands should have issues with bill.EURO is a great model in the tropics and called this recurve days ago.As of 12z bill is already moving wnw.


Here fishy fishy fishy.
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Quoting WPBHurricane05:


Interesting. Bill is still one to watch for the Leeward Islands, Bahamas, and the East Coast.


Dont think even the islands should have issues with bill.EURO is a great model in the tropics and called this recurve days ago.As of 12z bill is already moving wnw.
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Quoting morningmisty:
Good Morning everyone,

I live in the Tampa Bay area. Does anyone have the latest info on TD 04? Thanks.


your in the clear
Member Since: September 30, 2007 Posts: 9 Comments: 15962
I am going to tropics chat, wanna join
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Quoting Walshy:



Conditions are good, but I think it will move over land fast before it tries to pull a Humberto.


The reason I say 50MPH, is because it should have sufficient convection around its center to allow it to consolidate effectively. Inflow would be abundant in all channels.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting HurricaneKyle:
So let me get this straight on the general feeling of the blog.

Ana is (again apparently) going to dissipate.

Bill was hype and is going out to sea.
(wasn't Ike called 'hype'?)

TD4/Claudette is going to be nothing more than a thunderstorm even though SST's are some of the hottest on Earth. Never know, think of Humberto.

:)


You've got it!
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4722. Walshy
Quoting LAnovice:


No - "I'll have an update Sunday. Jeff Masters "
See Saturday's update (at the end)



hahaha sarcasm at its finest.
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So let me get this straight on the general feeling of the blog.

Ana is (again apparently) going to dissipate.

Bill was hype and is going out to sea.
(wasn't Ike called 'hype'?)

TD4/Claudette is going to be nothing more than a thunderstorm even though SST's are some of the hottest on Earth. Never know, think of Humberto.

:)
Member Since: August 10, 2009 Posts: 3 Comments: 672
hurricanejunkie, you have mail
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Your right Allstar
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4718. Hhunter
Quoting CaneWarning:


I forget some people go to church these days. I don't know a single person who goes unless there is a wedding or funeral!
that is to bad
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4717. sfla82
Quoting bajelayman2:


Unfortunately, Bill may be this year's Katrina or Andrew, in damage terms.

He definitely looks impressive already and covers a large area.


LOL...No it wont....It would have to hit land first and right now the only land in danger is Bermuda.
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Anyone here think that TS Ana, IF it makes it to the GOM, could regenerate once it hits those unobstructed warm SST's?
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4715. Walshy
Quoting futuremet:
Claudette will strengthen rapidly after reaching 50MPH. A well defined anticyclone is currently over, providing good upper level divergence.



Conditions are good, but I think it will move over land fast before it tries to pull a Humberto.
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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.