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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Funny wording! Recommends action for people and FISH? OK, so maybe mariners are people, too

------

i think they mean fisherman and their vessels.
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TROPICAL DEPRESSION FOUR LOCAL STATEMENT
NATIONAL WEATHER SERVICE TALLAHASSEE FL631 AM EDT SUN AUG 16 2009

...TROPICAL STORM WARNING ISSUED FOR NEW DEPRESSION IN THE
EASTERN GULF OF MEXICO...

THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND
RECOMMENDED ACTIONS FOR PEOPLE AND MARINE INTERESTS IN
THE FLORIDA PANHANDLE AND BIG BEND...AS WELL AS THE COASTAL
WATERS OF THE NORTHEASTERN GULF OF MEXICO.

Funny wording! Recommends action for people and FISH? OK, so maybe mariners are people, too.
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4362. szqrn1
Quoting HurricaneFCast:

Yeah I'd pretty much call it a definite landfall tonight in the Florida Panhandle.. Its inside 24 hours now, where there is little chance for an error larger than maybe 50 miles..


We may not feel it at all then... I figured this was gonna intensify overnight.
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4361. breald
It looks like Bermuda needs to keep an eye out for Bill. Hopefully it does not get close to either the East Coast or Bermuda.
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Quoting szqrn1:
morning..just getting up here on MS gulf coast.... TD 4 still looking like she is going to FL?

Yeah I'd pretty much call it a definite landfall tonight in the Florida Panhandle.. It's inside 24 hours now, where there is little chance for an error larger than maybe 50 miles..
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Quoting Ossqss:
We we could go from none to 3 named storms in a matter of, what 48 hours?


Even less. Just over 24. Ana (believe it or not) was only named yesterday morning.
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even though ppl SHOULD be prepared overall for hurricane season, i have a feeling that cluadette (td4) will catch alot of ppl off guard. at least the NHC issued TS warnings now and not at the absolute last minute like in humberto. while this storm likely wont cause widespread damage, people will have little time to secure loose items and possibly evacuate (if they live in a flood area or mobile home)

even though i feel it wont reach hurricane status, with its small size, it has the potential to intensifty quickly and i think the NHC should also issue hurricane watches just in case.

any thoughts on this?
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Quoting szqrn1:
morning..just getting up here on MS gulf coast.... TD 4 still looking like she is going to FL?

Yup, Im guessing around Destin and east..my uneducated guess is the point of the panhandle...
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Another bad thing is... this might not even be it for the Gulf. 97 was a strong El Nino year, and had Danny (same naming list), but that was it.

The latest 5 day forecast has the remnants of Ana (It's taking a trip through Cuba/Hispaniola, not much tends to remain after that) entering the Gulf.
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4355. szqrn1
morning..just getting up here on MS gulf coast.... TD 4 still looking like she is going to FL?
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4354. Ossqss
We we could go from none to 3 named storms in a matter of, what 48 hours?
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Quoting IKE:
Tropical Storm Wind warning and statement for panhandle of Florida...

True.....



There it is....



Ike,
My prediction of 8 storms in August a few weeks back still has hope :)
Member Since: July 7, 2005 Posts: 0 Comments: 5306
4352. IKE
Quoting sporteguy03:


Not saying it to you but people should be prepared June 1st, it went from low to high chance and designated as a TD#4, when it counted the NHC did act fast. If one is not prepared well that person has been snoozing since June 1st.


True.....

Quoting GeoffreyWPB:
2009 Storms
All Active Year


Atlantic
04L.CLAUDETTE
03L.BILL
02L.ANA


There it is....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
4343. keywestbrat 10:47 AM GMT on August 16, 2009
Yowza,
Well it just goes to show, that even the best predictions are just that, yesterday there was no chance of the keys swirl becoming anything because of the high pressure over the gulf, but now we have TD and were off to the races LOL
-------
i have to agree. only a few ppl last night felt this would develop. tampaspin, drak, and i were a few of them. but with SSTs as high as they are and favorable conditions, i wasnt surprised too much that it developed.

i still stick with my prediction of a weak TS by this afternoon before it makes landfall. however, with the good presentation on radar and its relatively small size, i also give it an outside chance (although unlikely) that it reaches strong TS status. unless it pulls a humberto, i dont think it has enough time to reach hurricane status.
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4350. bcn
Nicaragua/Honduras seems also very activity for future developments?:

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2009 Storms
All Active Year


Atlantic
04L.CLAUDETTE
03L.BILL
02L.ANA
Member Since: Posts: Comments:
Quoting IKE:


80%, maybe higher, of people don't follow the tropics like we do.


Not saying it to you but people should be prepared June 1st, it went from low to high chance and designated as a TD#4, when it counted the NHC did act fast. If one is not prepared well that person has been snoozing since June 1st.
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4346. IKE
...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
I see Claudette is up on the FNMOC page. What a difference a day makes!
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TROPICAL DEPRESSION FOUR LOCAL STATEMENT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
631 AM EDT SUN AUG 16 2009

...TROPICAL STORM WARNING ISSUED FOR NEW DEPRESSION IN THE
EASTERN GULF OF MEXICO...

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND
RECOMMENDED ACTIONS FOR PEOPLE AND MARINE INTERESTS IN
THE FLORIDA PANHANDLE AND BIG BEND...AS WELL AS THE COASTAL
WATERS OF THE NORTHEASTERN GULF OF MEXICO.

.WATCHES/WARNINGS...
A TROPICAL STORM WARNING IS IN EFFECT FOR THE COASTAL COUNTIES
OF THE FLORIDA PANHANDLE AND BIG BEND...AS WELL AS THE COASTAL
WATERS OF THE NORTHEASTERN GULF OF MEXICO.

A TROPICAL STORM WIND WARNING IS IN EFFECT FOR THE INLAND FLORIDA
PANHANDLE...INCLUDING LIBERTY COUNTY.

A WARNING MEANS THAT THE STATED CONDITIONS ARE EXPECTED WITHIN
THE NEXT 24 HOURS FOR THE SPECIFIED AREAS.
A FLOOD WATCH IS IN EFFECT FOR THE FLORIDA PANHANDLE AND WESTERN
FLORIDA BIG BEND.

PLEASE CHECK THE LATEST PUBLIC AND MARINE FORECASTS FOR DETAILED
INFORMATION ABOUT ADDITIONAL HAZARDS.

.STORM INFORMATION...
AT 5 AM EDT...OR 4 AM CDT...THE CENTER OF TROPICAL DEPRESSION
FOUR WAS LOCATED NEAR LATITUDE 27.7 NORTH...LONGITUDE 83.9 WEST...
OR ABOUT 90 MILES WEST-SOUTHWEST OF TAMPA FLORIDA. THIS IS ABOUT
200 MILES SOUTH-SOUTHEAST OF PANAMA CITY FL...OR ABOUT 190 MILES
SOUTH OF TALLAHASSEE FL. THE DEPRESSION IS MOVING NORTH-NORTHWEST
NEAR 16 MPH. ON THE FORECAST TRACK...THE CENTER OF THE DEPRESSION
SHOULD BE VERY NEAR THE NORTHERN GULF COAST OF FLORIDA BY LATE
THIS AFTERNOON. MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH WITH
HIGHER GUSTS. STRENGTHENING IS EXPECTED AND THE DEPRESSION IS
FORECAST TO BECOME A TROPICAL STORM PRIOR TO REACHING THE
COASTLINE.

.SITUATION OVERVIEW...
TROPICAL DEPRESSION FOUR IN THE EASTERN GULF OF MEXICO IS
EXPECTED TO INTENSIFY TO A TROPICAL STORM LATER THIS EVENING
BEFORE MAKING LANDFALL ALONG THE PANHANDLE COAST.

.PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS A GOOD TIME FOR RESIDENTS TO GO OVER THEIR DISASTER PLANS.
VISITORS ARE ENCOURAGED TO CHECK WITH HOTEL MANAGEMENT OR WITH
LOCAL OFFICIALS REGARDING ANY ACTIONS THEY SHOULD TAKE.

FOR COASTAL LOCATIONS AND PLACES PRONE TO COASTAL FLOODING...
TROPICAL CYCLONES BRING BOTH HIGH WINDS AND STORM SURGE...
TORRENTIAL RAINS AND LOCAL FLOODING.

FOR THE MARINE WATERS...TROPICAL CYCLONES GENERATE HIGH WINDS AND
DANGEROUS SEAS.

TORNADOES...AND WATERSPOUTS OFTEN ACCOMPANY TROPICAL CYCLONES.

&&

.NEXT UPDATE...
THE NEXT LOCAL STATEMENT WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE IN TALLAHASSEE AROUND 9 AM EDT...OR SOONER IF CONDITIONS
WARRANT.

FLZ007-009>011-013-026-161300-
/O.NEW.KTAE.TI.W.0001.090816T1031Z-090818T0000Z/
INLAND WALTON-HOLMES-WASHINGTON-JACKSON-CALHOUN-LIBERTY-
631 AM EDT SUN AUG 16 2009 /531 AM CDT SUN AUG 16 2009/

...TROPICAL STORM WIND WARNING IN EFFECT UNTIL 8 PM EDT /7 PM
CDT/ MONDAY...

...NEW INFORMATION...
A TROPICAL STORM WIND WARNING HAS NOW BEEN ISSUED. A MORE
DETAILED STATEMENT WILL FOLLOW SHORTLY.

$$

JAMSKI/BARRY
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4342. IKE
Dmax is firing TD4 up....

Shear is 5-10 knots....

Nice vorticity increasing....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
ADT's first update:

Final T# Adj T# Raw T#
(3hr avg)
2.1 2.2 2.5

Raw of a TS.
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4340. Ossqss
Mornin all, go to sleep and poof there is another TD in the Gulf .
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Quoting IKE:


It looks better each update on radar.


Yea, storm activity is increasing dramatically.
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wow, i go to sleep fo r6 hrs, wake up and theres a low pressure system in the gulf. last night i predicted it might be able to reach weak TS status.

what is the current status of 91L? has it reached TD status yet or is it just considered a broad low pressure system? thanks for any replies

nvm lol i just turned on TWC and i see its a TD4 now with TS warnings in the panhandle.
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I see Guadloupe >>>>>>>>>> having a visitor
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4336. IKE
Quoting HurricaneFCast:

I gotcha. Lol, it would be crazy for residents to wake up to a TS without having even known there was a Depression or an Invest! Luckily they'll have about half a day to prepare... Lol.. Just better hope, for everyone's sake, (including yours IKE!!!) that this doesn't rapidly strengthen. Although with its small size, only residents near the center (maybe within ~50 miles on either side) will feel the majority of the effects.


It looks better each update on radar.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Today is going to be a scorcher here in Barbados. Not a breath of wind.
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4334. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


No...lol....I'm saying here as in designated.

I gotcha. Lol, it would be crazy for residents to wake up to a TS without having even known there was a Depression or an Invest! Luckily they'll have about half a day to prepare... Lol.. Just better hope, for everyone's sake, (including yours IKE!!!) that this doesn't rapidly strengthen. Although with its small size, only residents near the center (maybe within ~50 miles on either side) will feel the majority of the effects.
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4332. HadesGodWyvern (Mod)
haha guess so Cotollion no wonder
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4331. Walshy
Tropical Storm watch for Virgin Islands too.
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Morning Bimshire,
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Quoting IpswichWeatherCenter:



Look at: Scene Type - that will tell you.

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 16 AUG 2009 Time : 091500 UTC
Lat : 27:45:13 N Lon : 83:55:57 W


CI# /Pressure/ Vmax
2.0 /1009.0mb/ 30.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.0 2.0 2.0

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -45.6C Cloud Region Temp : -32.7C

Scene Type : USER DEFINED INITIAL CLASSIFICATION

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************



Yes, those are the ADT ratings, the same ones that are posted to CIMSS...
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4328. HadesGodWyvern (Mod)
uh-oh WU is messing up their tropical cyclone map for 01W (Kujira) with naming filing 01C as wp200901
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4327. IKE
Quoting HurricaneFCast:

Well the center won't be there until the evening.. but I guess if you mean you'll begin to feel the effects, then I suppose by lunchtime is possible.. But by 8am EST???? I don't know about that Ike.. Lol. Does this thing have jets on it?


No...lol....I'm saying here as in designated.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting HadesGodWyvern:
oh I guess the JTWC has it going northeast as well.. last I saw the track map it was tracking northwest


Well, the maps say it will eventually loop to the west. Guess it wants to make a detour first.
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Quoting HurricaneFCast:

Well the center won't be there until the evening.. but I guess if you mean you'll begin to feel the effects, then I suppose by lunchtime is possible.. But by 8am EST???? I don't know about that Ike.. Lol. Does this thing have jets on it?


Think he meant the storm being named, not making landfall...
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Gwadaman, put Ana on a loop and tell me what you think?
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Quoting IKE:
Claudette will be here by 10 am CDST...maybe by 7...based on radar trends....

Well the center won't be there until the evening.. but I guess if you mean you'll begin to feel the effects, then I suppose by lunchtime is possible.. But by 8am EST???? I don't know about that Ike.. Lol. Does this thing have jets on it?
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Quoting IpswichWeatherCenter:


oh right... LOL - insert uber-massive bloop here.

When do you think we will start to get slightly sensible numbers then?


Hard to say, CIMSS hasn't been updating ADT as smoothly as they usually do lately.

2-3 results should give an idea on trends and intensity. However, by that time, we'll have the 8am advisory.

The next SAB dvorak is out in about an hour, as well, at 1145UTC. (745EDT/645CDT). That should give a decent picture.

The model runs for 12z should also be out in roughly 2 hours. We may have Claudette by then, so there might be better initialisation. We'll see.
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I really want to stay up to see how "Claudette" forms, but it's 3:30 am here on the West Coast of Canada and I'm tired. Wouldn't be surprised to wake up to a Hurricane the way the depression is rapidly organizing. Night all ^^
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Good Morning 456, what's your forcast on Bill this morning........
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4319. IKE
Scrolling on TWC now....
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4318. HadesGodWyvern (Mod)
oh I guess the JTWC has it going northeast as well.. last I saw the track map it was tracking northwest
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Quoting Cotillion:
That's because they're just starting the initialisation, Ipswich.



oh right... LOL - insert uber-massive bloop here.

When do you think we will start to get slightly sensible numbers then?
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4316. IKE
Quoting neonlazer:

I do see how this is really going to freak alot as they will not know about it till they wake up and its just offshore..but..not like anyone can do anything..cant have loudspeaker in a blimp saying "TS IS COMING THIS WAY RUNN!!" lol..Not really anyones fault..nature just wanted to get some payback i guess..


80%, maybe higher, of people don't follow the tropics like we do.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
That's because they're just starting the initialisation, Ipswich.

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Quoting IKE:
Claudette will be here by 10 am CDST...maybe by 7...based on radar trends....

I do see how this is really going to freak alot as they will not know about it till they wake up and its just offshore..but..not like anyone can do anything..cant have loudspeaker in a blimp saying "TS IS COMING THIS WAY RUNN!!" lol..Not really anyones fault..nature just wanted to get some payback i guess..thank God it wont be a strong hurricane..
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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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