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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Bill SHIPS

* ATLANTIC SHIPS INTENSITY FORECAST *
* GOES DATA AVAILABLE *
* OHC DATA AVAILABLE *
* BILL AL032009 08/15/09 18 UTC *
Member Since: Posts: Comments:
Quoting stormwatcherCI:
NRL Monterey Marine Meteorology Division (Code 7500) Tropical Cyclone Page (Ver.4.38.03)
Development Team
NOTE: Processing delays, please check all dates/times [Saturday]


Ah, makes sense.

Thanks. Coincidentally, as soon as it is mentioned, it comes through!
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting serialteg:


Nice NE turn for Ana, can someone explain to me the trough-like cord connecting them? Pretty awesome
Looks like Ana is towing TD3
Member Since: Posts: Comments:
Quoting FLHurricaneChaser:
We have Bill


AL, 03, 2009081518, , BEST, 0, 113N, 345W, 35, 1006, TS, 34, NEQ, 25, 25, 0, 25,


yep
Member Since: July 24, 2005 Posts: 407 Comments: 19076
000
WHXX01 KWBC 151942
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1942 UTC SAT AUG 15 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE BILL (AL032009) 20090815 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090815 1800 090816 0600 090816 1800 090817 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 11.3N 34.5W 11.6N 36.9W 12.2N 39.6W 13.0N 42.2W
BAMD 11.3N 34.5W 11.4N 37.1W 11.8N 39.8W 12.4N 42.5W
BAMM 11.3N 34.5W 11.3N 37.1W 11.7N 39.8W 12.4N 42.5W
LBAR 11.3N 34.5W 11.1N 37.6W 11.5N 41.4W 11.9N 45.2W
SHIP 35KTS 42KTS 49KTS 57KTS
DSHP 35KTS 42KTS 49KTS 57KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090817 1800 090818 1800 090819 1800 090820 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 13.9N 44.9W 15.8N 51.3W 17.8N 58.3W 19.6N 64.7W
BAMD 13.2N 45.3W 15.0N 50.2W 18.2N 55.0W 22.1N 60.2W
BAMM 13.3N 45.2W 15.5N 50.7W 18.1N 57.1W 20.4N 63.5W
LBAR 12.5N 49.1W 13.1N 55.8W 16.9N 57.6W .0N .0W
SHIP 65KTS 80KTS 86KTS 89KTS
DSHP 65KTS 80KTS 86KTS 89KTS

...INITIAL CONDITIONS...
LATCUR = 11.3N LONCUR = 34.5W DIRCUR = 265DEG SPDCUR = 15KT
LATM12 = 11.8N LONM12 = 32.0W DIRM12 = 264DEG SPDM12 = 13KT
LATM24 = 11.8N LONM24 = 29.2W
WNDCUR = 35KT RMAXWD = 25NM WNDM12 = 30KT
CENPRS = 1004MB OUTPRS = 1011MB OUTRAD = 200NM SDEPTH = M
RD34NE = 25NM RD34SE = 25NM RD34SW = 0NM RD34NW = 25NM

$$
NNNN
Member Since: August 23, 2008 Posts: 7 Comments: 5300
908. jpsb
Quoting Weather456:
456, what is that purple thing pointing at the Tx/La border? Thanks
Member Since: June 30, 2009 Posts: 0 Comments: 1190
Quoting hunkerdown:
did you honestly pay any attention to the time on that image, FRIDAY 8:00 am.


yes...it's the last frame of the run. Did I miss something?
Member Since: Posts: Comments:
906. IKE
Quoting Skyepony:
0145 PM NON-TSTM WND GST 8 SSE KEY LARGO 25.01N 80.38W
08/15/2009 M46.00 MPH GMZ052 FL C-MAN STATION

A SOUTH-SOUTHWESTERLY WIND GUST OF 40 KTS...OR 46
MPH...WAS RECORDED BY THE C-MAN STATION ON MOLASSES REEF
LIGHT AT 145 PM EDT. THIS GUST WAS FROM A HEAVY
SHOWER...ASSOCIATED WITH A PASSING TROPICAL WAVE.


&&

$$

ROSS


TS winds and it's not even labeled an invest.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Cotillion:


Possibly. Pacific has the same problem?

I know Ana (and maybe Guillermo by now, haven't really checked SSD or ADT for that) is weakening and TD3 is just chugging along.. maybe hard to get a handle. But wouldn't of thought it'd take over an hour.

Must be something technical, you're probably right.
NRL Monterey Marine Meteorology Division (Code 7500) Tropical Cyclone Page (Ver.4.38.03)
Development Team
NOTE: Processing delays, please check all dates/times [Saturday]
Member Since: Posts: Comments:


Nice NW turn for Ana, can someone explain to me the trough-like cord connecting them? Pretty awesome
Member Since: August 22, 2006 Posts: 2 Comments: 1983
The visible imagery of TD 3 indicates it continues to wind up, not sure much persons is seeing that
Member Since: July 24, 2005 Posts: 407 Comments: 19076

ANA

Bill

AOI

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guys how long till the Hurricane Hunters fly into TS Ana
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We have Bill


AL, 03, 2009081518, , BEST, 0, 113N, 345W, 35, 1006, TS, 34, NEQ, 25, 25, 0, 25,
Member Since: Posts: Comments:
Quoting nrtiwlnvragn:
Subject to change, they are indicating AL03 is now a TS

AL 03 2009081518 BEST 0 113N 345W 35 1006 TS


Thanks I was looking for that
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting WeatherStudent:


Afternoon 456! Which one are you buying into, my friend?


The southerly tracks, unfortnunately seems more reasonable for several reasons:


where TD 3 formed, more south than expected

its forward speed, fast=more west, slower=more pull north. TD 3 has speed up today since it became more organize

its motion and located, at 11.5N moving off towards the west, that very low, especially since the models had this at 14N at that very same latitude
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Subject to change, they are indicating AL03 is now a TS

AL 03 2009081518 BEST 0 113N 345W 35 1006 TS
Member Since: Posts: Comments:
Quoting mikatnight:
did you honestly pay any attention to the time on that image, FRIDAY 8:00 am.
Member Since: Posts: Comments:
Quoting FLfishyweather:
Hi guys, I haven't been on in a year or two. I live near Ft Lauderdale and I'm 13. I'll admit, I am half on here because of the whole missing school thing (which was incredible luck last year as the first day of school was cancelled) but I also find the tropics interesting.


Hey FLfishy -
Welcome to the Blog. Me & my wife are up here in Lantana. Guess it finally got interesting out there, uh?
Member Since: Posts: Comments:
Quoting Funkadelic:


Lol Rejected!, its all good brutha that was a smooth move you tried to lay down there. ;)


we do try our best, huh?
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Quoting nrtiwlnvragn:


On every storm, Atlantic and Pacific? Maybe communications problem? I was wondering myself why no 18Z guidance.


Possibly. Pacific has the same problem?

I know Ana (and maybe Guillermo by now, haven't really checked SSD or ADT for that) is weakening and TD3 is just chugging along.. maybe hard to get a handle. But wouldn't of thought it'd take over an hour.

Must be something technical, you're probably right.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
891. JLPR
Quoting Weather456:
Dmaz will explode Td 3 into a moderate TS


well that would be a great D-max xD
Member Since: Posts: Comments:
Quoting truecajun:


you weren't ignored. i got a laugh out of it!


that's better! :D :D :D :D

rainin here now in puerto rico... hope to have my electric generator here soon to be able to report live while storm passes if comes to that. and obviously if internet holds
Member Since: August 22, 2006 Posts: 2 Comments: 1983
#876, weather456,

I agree; they both still look pretty good. Of course TD3 is the largest and best looking right now.

time will tell.


Stormtop was funny in 2005; just go read some of those archive blogs! LOL

and he did "nail" Katrina before anyone else.. but then again, he called EVERY STORM to follow that course and hit New Orleans ,, Eventually one did.
Member Since: Posts: Comments:
Ana and Bill are slowly taken thier time to develope, but when they get to about 65W to 70W Im guessing by the models, that rapid intensification as Dr Masters said, is very possible for both. This is not good for S Fl. or GOM. Ive been trying to understand stearing patterns and that is where it looks like thier going. Is it true if they arent developed well while traveling the Atlantic, that storms go W or WNW and when they are forecasted to develope better closer to USA, they dont curve out?
Quoting FMDawg:


It's pouring right now in Fort Myers. Looks to be headed your way soon.


Haven't seen one drop of rain in Ft Myers yet although seems like that will change very shortly. Very overcast and breezy
Member Since: Posts: Comments:
886. IKE
TD3.....looks like it's head got chopped off.....




Ah-nah.....TS?



Member Since: June 9, 2005 Posts: 23 Comments: 37858
Dmax will explode Td 3 into a moderate TS
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting WeatherStudent:

I would be surprised if a 00Z CMC/ECMWF blend were to succeed...



Impressive observation.
Member Since: Posts: Comments:
882. CJ5
Quoting 996tt:
Anybody checked buoy data or pressures off Key West?


Yep, several times and didn't find a single one below 30.
Member Since: Posts: Comments:
860. WeatherStudent 7:33 PM GMT on August 15,
I would be surprised if a 00Z CMC/ECMWF blend were to succeed.

Evaluating the sigma levels I do not see where these models are deriving their impetus in causing that much beta motion between 72 and 120 hours, particularly when the steering field remains so longitudinal in orientation. Beginning at this latitude and having virtually no weakness in the ridge modeled out through 144 or so hours, I don't see where that much polar-ward motion is actually going to come from.

I'm considering these models the less likely outliers until I find a reason that fits.

That said, the 12Z CMC did come a tad further west of the 00Z fixes.

I believe everyone from the northern Gulf Coast to Maine needs to be paying attention to the tropics/outlooks over the course of the next week to 10 days.

Ana is tough one to call. I am wondering if her small size has the models only vaguely aware of the system's presence. The U/A wind shows a relaxed shear, yet convection struggles at the current hour. WV imagery suggest pretty strongly that the culprit is a few gulps of dry air. This may continue (...and continue to baffle the models) until she grows (if and when) in size and contains her own environment at the core. She's just not big enough to produce that inward environment just yet.

I believe the difference in the track guidance in why Ana winds up in the Gulf and "Bill" ends up along the East Coast or headed for England is because of scale of development - the weaker systems are reliant on lower level steering.


Kid, you really need to get laid rather than hanging out 24/7 on a weather blog site being nerdy.




Member Since: July 29, 2009 Posts: 0 Comments: 72
Bill is moving faster than Ana, so survival of ana is so so, lol
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Cotillion:
Still no info on the 18z runs.

Maybe they can't decide what to set for the initial intensities?


On every storm, Atlantic and Pacific? Maybe communications problem? I was wondering myself why no 18Z guidance.
Member Since: Posts: Comments:
Tropical Depression continues to organize into Bill

Member Since: July 24, 2005 Posts: 407 Comments: 19076
875. JLPR
Quoting Weather456:


starting to develop some convection
by the way the convection looks I think we wont have Bill at 5pm unless it explodes soon
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Quoting Weather456:

Bill is getting more near to Ana. There is just 1 qudrant between them.
Member Since: Posts: Comments:
873. 996tt
Anybody checked buoy data or pressures off Key West?
Member Since: Posts: Comments:
Quoting rxse7en:
For those of lifers we know who he is, know not to take him too seriously. It's been posted before that it's illegal/immoral to pretend to be an official statement. I'm just looking out for casual readers. I haven't suggested banning or anything, just that he understands that there are people on here that don't know and may rely on his post if it looks official. If I'm wrong, I apologize.


I totally understand your point. I don't think his posts are too dangerous because he always exaggerates on the high side. I would rather have someone do that then the ones who come on and say "nothing to worry about". (EYE) At least if someone takes it seriously they will be more prepared instead of less. His ridiculous posts before Katrina might have actually saved some people. I just think they are kinda funny.
Member Since: Posts: Comments:
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting CapeCoralStorm:
I find it interesting that the weather is so bad in miami, naples, brandenton,sarasota, and pretty much everywhere in south florida EXCEPT for fort myers/cape coral. It hasnt rained at all today. overcast and breezy. Strange.


It's pouring right now in Fort Myers. Looks to be headed your way soon.
Member Since: Posts: Comments:
Hi guys, I haven't been on in a year or two. I live near Ft Lauderdale and I'm 13. I'll admit, I am half on here because of the whole missing school thing (which was incredible luck last year as the first day of school was cancelled) but I also find the tropics interesting.
Member Since: Posts: Comments:
868. Skyepony (Mod)
0145 PM NON-TSTM WND GST 8 SSE KEY LARGO 25.01N 80.38W
08/15/2009 M46.00 MPH GMZ052 FL C-MAN STATION

A SOUTH-SOUTHWESTERLY WIND GUST OF 40 KTS...OR 46
MPH...WAS RECORDED BY THE C-MAN STATION ON MOLASSES REEF
LIGHT AT 145 PM EDT. THIS GUST WAS FROM A HEAVY
SHOWER...ASSOCIATED WITH A PASSING TROPICAL WAVE.


&&

$$

ROSS
Member Since: Posts: Comments:
Quoting Michfan:


Is it me or does there seem to be more banding going on with it?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I find it interesting that the weather is so bad in miami, naples, brandenton,sarasota, and pretty much everywhere in south florida EXCEPT for fort myers/cape coral. It hasnt rained at all today. overcast and breezy. Strange.
Member Since: Posts: Comments:

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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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