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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Quoting CaneWarning:
Local met says we don't need to worry about either of these storms. Ana will probably be very weak, while Bill should curve out to sea.
Hey Cane! They may bring a little rain and perhaps some lightning to your area :o)
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Quoting WeatherMSK:


Thank you I'm not alone with this thinking.


I agree with the statement as well.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting stormwatcherCI:
I'm sure. I work in the parcel department now but have worked in incoming mail, outgoing international, stamp counter etc. Everything done manually but some things with computers.
well let's pray neither of us have to worry about any of these entities...good luck and be safe
Member Since: July 31, 2009 Posts: 0 Comments: 324
Quoting jrweatherman:
It is still too early to say what will happen with Bill.

I can tell you that Fl is safe with Bill. Everything is coming into place for that right turn to the north. The question is, will Bill curve back to the NE or drive into the Carolinas or up the NE coast.


Thank you I'm not alone with this thinking.
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1760. BrandiQ
Quoting WeatherStudent:
Oh great! WSVN has finally begun it's 24-7 storm coverage, all because we are in Ana's future cone of uncertainty. Those people are something else.


Great now I can hear Phil say "Dirty Side" for the next 5 days...
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Hey all,

I just got back from a long vacation to visit family in Michigan, had a great time. Didn't have access to the WUnderground..

Ana, looks to be giving up, but she will probably make it through dust.

Bill, wish we will soon be callin Mr. Bill, is just pressin forward, and gettin it self lookin good. Models has this thing goin anywhere from the gulf to the east coast, and I think the gulf don't need another hurricane with the anniversary of Katrina coming up.

Claudette, well she is named yet, but like a meteorologist from da TWC said in a webcast, she could be right behind Bill. Why, look at this impressive vigorous wave comin off of africa.

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Quoting CaneWarning:
I'm starting to think some people want these storms to hit them.


You're darn right I do. I want something to chase.
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1757. Drakoen
Quoting Funkadelic:


Do you think the models are going to stay like that showing a recurveature? I still think these models are waste for anything more then 3-4 days out


I cannot say. The models have the luxury of flipping back and forth as they please. I, however, don't have the patience to debate over whether or not the runs are valid. Best to wait until the system gets closer to the Lesser Antilles.
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1756. Patrap
Member Since: July 3, 2005 Posts: 419 Comments: 127374
It is still too early to say what will happen with Bill.

I can tell you that Fl is safe with Bill. Everything is coming into place for that right turn to the north. The question is, will Bill curve back to the NE or drive into the Carolinas or up the NE coast.
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Quoting WeatherStudent:
Oh great! WSVN has finally begun it's 24-7 storm coverage, all because we are in Ana's future cone of uncertainty. Those people are something else.
LMAO
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Quoting BrandiQ:


But that's still 8 days from now. The models are bound to change....

the most use words for the few days will be... recurve abd the models will change
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Quoting CatastrophicDL:
Wow, leave the computer for a day and see what happens. The tropic are heating up and we have a cold wave here! Hey all!


It's all your fault!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Drakoen:
It is still too early to say what will happen with Bill.
So you think anything is possible with Bill?
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Quoting KATRINABILOXIGIRL:
i'll bet that's real different to what I do
I'm sure. I work in the parcel department now but have worked in incoming mail, outgoing international, stamp counter etc. Everything done manually but some things with computers.
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Quoting P451:
GFS 18Z

Drops Ana altogether.
Recurves Bill even more and makes him far more intense than before.
Backs off strength of Claudette (the currently emerging African wave).
Forms a fourth system far east of Caludette - presumably the wave currently over central Africa that looks decent.



If Ana makes it south of the islands then perhaps she'll be able to tap into the moisture taht is so bountiful in the western caribbean. I'm from South Florida, will be here until the 19th, but then i am due to go back to tallahassee. tallahassee does not get much storms.. so i am not too worried. however with the little i know, i do think Ana looks to be a GOM storm, mostly because it has remained weak and may not get picked up by northern pushing steering currents.
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Wow, leave the computer for a day and see what happens. The tropic are heating up and we have a cold wave here! Hey all!
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Local met says we don't need to worry about either of these storms. Ana will probably be very weak, while Bill should curve out to sea.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting Patrap:
ANA Graphics Archive,and current track
don't like the looks of that one Pat
Member Since: July 31, 2009 Posts: 0 Comments: 324
1742. Drakoen
Models keep flipping back and forth with this trough. Yesterday the GFS was talking about it getting into the GOM and now it wants recurvature.
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guys bill is like 3200 or some in so its way way out there and there is a lot of time too watch the mode runs
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1740. Relix
Quoting CaneWarning:
I'm starting to think some people want these storms to hit them.


I wouldn't mind Ana here in PR. As long as she's weak.
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Quoting atmoaggie:

Is that really the dynamics it is considering that kills Ana? I wouldn't think Anguilla was enough land to do that.
LMAO
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1738. BrandiQ
Quoting CaneWarning:
I'm starting to think some people want these storms to hit them.


Or maybe they just want to be proactive and prepared. I hope no one really wants a storm to hit them...
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1737. Patrap
ANA Graphics Archive,and current track
Member Since: July 3, 2005 Posts: 419 Comments: 127374
Based on the 18z GFS, Bill will be a Fish Storm
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Quoting stormwatcherCI:
Nice to meet you too. No carriers here. You have to check a P O Box or General Delivery.
i'll bet that's real different to what I do
Member Since: July 31, 2009 Posts: 0 Comments: 324
Quoting RyanFSU:
HWRF 18Z kills off Ana ... too much land interaction.


Is that really the dynamics it is considering that kills Ana? I wouldn't think Anguilla was enough land to do that. Looks like something else at play there...starts the kill well before land.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
1733. Dakster
Patrap - How's that trip to Seattle looking? Want company?

We just have to skip Northern California. No sense in going from the "frying pan to the fire!"

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bill will be makeing a hard turn too the right when he dos start turning or if he dos
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1730. RyanFSU
18Z HWRF takes Bill to Category 5, as it does with every storm over water that is at least 26C, and sometimes that doesn't even stop it.

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OBSERVATION #6
IF YOU DO NOT UNDERSTAND VISIT THIS LINK: Link
UZNT13 KWBC 152302
XXAA 65222 99190 70533 04293 99015 27228 08017 00129 26023 08020
92814 21631 09528 85545 18021 09522 70187 09650 10525 50590 06520
11013 40761 16958 10004 30971 31975 27504 25097 41970 23017 20245
533// 20524 88999 77999
31313 09608 82220
51515 10190 15424
61616 NOAA9 WX02A ANA OB 06
62626 SPL 1899N05334W 2235 MBL WND 08523 AEV 20801 DLM WND 13510
014152 WL150 08020 082 REL 1897N05330W 222052 SPG 1899N05334W 223
526 =
XXBB 65228 99190 70533 04293 00015 27228 11850 18021 22659 07257
33627 04456 44610 03260 55591 01226 66546 01933 77527 03926 88511
05356 99499 06519 11473 08732 22454 10756 33447 11361 44438 12550
55431 12966 66423 14175 77418 14573 88414 15162 99409 15564 11401
16758 22390 17967 33370 20968 44363 21957 55350 23959 66344 24967
77334 26562 88326 27576 99280 35573 11203 52763 22152 64938
21212 00015 08017 11962 09530 22939 09530 33898 08523 44850 09522
55647 11029 66527 12513 77443 09503 88300 28004 99270 22514 11239
23521 22203 21024 33193 19030 44176 19532
31313 09608 82220
51515 10190 15424
61616 NOAA9 WX02A ANA OB 06
62626 SPL 1899N05334W 2235 MBL WND 08523 AEV 20801 DLM WND 13510
014152 WL150 08020 082 REL 1897N05330W 222052 SPG 1899N05334W 223
526 =


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Quoting KATRINABILOXIGIRL:
yes I am a rural carrier in Gulfport Mississippi...nice to meet a fellow postal worker
Nice to meet you too. No carriers here. You have to check a P O Box or General Delivery.
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I'm starting to think some people want these storms to hit them.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1726. Patrap
Hurricane Preparation
Member Since: July 3, 2005 Posts: 419 Comments: 127374
1725. Drakoen
It is still too early to say what will happen with Bill.
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Ana is now only half exposed, and Bill continues to organize.
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1723. RyanFSU
HWRF 18Z kills off Ana ... too much land interaction.

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Quoting Dakster:


The other way is "easier", but once you know the format..



yup.
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Quoting stormwatcherCI:
Are you a Postal worker ? I work for the Cayman Islands Postal Service.
yes I am a rural carrier in Gulfport Mississippi...nice to meet a fellow postal worker
Member Since: July 31, 2009 Posts: 0 Comments: 324
Quoting ALCoastGambler:
Do you have any messengers

mobilegirl...he or she wants to talk to you privately
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Link


Definitley some rotation there....
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1717. Relix
Ana is mounting her final comeback. She's in the last track of her battle against dry air and she seems to be doing pretty well. Now should come the strengthening process that will determine how North will she go. Or I see it that way. The greater masters of WU can correct me, I am ehre to learn and enjoy the show.
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Quoting nrtiwlnvragn:
I haven't seen any data from the NOAA P-3 plane, considering the current state of Ana they may have cancelled the mission. (P-3 is a low level, not the G-IV)
She seems to be trying to get her act together again.
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1714. BrandiQ
Quoting CaneWarning:
After looking at the GFS ensemble models for Bill, I feel much better for the state of Florida. It looks like Bill wants to recurve.


But that's still 8 days from now. The models are bound to change....
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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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