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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Something is brewing around Key West, FL. You can see rotation in the convection over the area on visible satellite imagery as well as RGB.
Member Since: October 21, 2008 Posts: 246 Comments: 3947
Perhaps explosive development.Near the keys
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TROPICAL STORM ANA LOCAL STATEMENT
NATIONAL WEATHER SERVICE SAN JUAN PR
101 PM AST SAT AUG 15 2009

...TROPICAL STORM ANA MAY IMPACT THE LOCAL ISLANDS BY MONDAY
EVENING...

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND
RECOMMENDED ACTIONS FOR PEOPLE AND MARINE INTERESTS IN SELECT
LOCATIONS AND THE COASTAL WATERS OF PUERTO RICO AND THE U.S.
VIRGIN ISLANDS.

.WATCHES/WARNINGS...
AT THIS TIME...THERE ARE NO TROPICAL CYCLONE WATCHES OR WARNINGS
IN EFFECT FOR OUR AREA. HOWEVER...AS THIS EVENT UNFOLDS...THE
ISSUANCE OF WATCHES AND WARNINGS MAY SOON BECOME NECESSARY.

.STORM INFORMATION...
AT 11 AM AST...THE CENTER OF TROPICAL STORM ANA WAS LOCATED NEAR
LATITUDE 14.3 NORTH...LONGITUDE 48.3 WEST...OR ABOUT 920 MILES
EAST OF THE LEEWARD ISLANDS.. THIS IS ABOUT 1200 MILES EAST OF
SAN JUAN PR...OR ABOUT 1140 MILES EAST-SOUTHEAST OF SAINT THOMAS
VI. ANA IS MOVING TOWARD THE WEST AROUND 16 MPH AND MAXIMUM
SUSTAINED WINDS WERE 40 MPH.

.SITUATION OVERVIEW...
AT THE PRESENT MOMENT...TROPICAL STORM ANA IS NOT WELL ORGANIZED
BUT THE FORECAST IS FOR THE STORM TO SLOWLY INTENSIFY DURING THE
NEXT TWO DAYS AS IT MOVES TOWARDS THE ISLANDS OF THE NORTHEAST
CARIBBEAN. AT THIS TIME...IT IS TOO EARLY TO PROVIDE EXACT
WIND...RAINFALL...AND SURGE FORECAST VALUES FOR SPECIFIC
LOCATIONS. A GENERAL CONCERN SHOULD BE FOR THE POSSIBILITY OF AT
LEAST DAMAGING WINDS AND LOCALIZED FLOODING SOMEWHERE WITHIN
PUERTO RICO AND THE U.S. VIRGIN ISLANDS.

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

EVEN BEFORE THE ISSUANCE OF WATCHES OR WARNINGS...IT MAY BECOME
NECESSARY FOR LOCAL AUTHORITIES TO CLOSE GOVERNMENT
AGENCIES...FERRY SERVICES...AND SCHOOLS. PLEASE STAY TUNED TO THE
YOUR FAVORITE MEDIA OUTLET FOR THE LATEST INFORMATION.

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

DO NOT FOCUS ON THE SKINNY BLACK LINE.

A TROPICAL STORM OR HURRICANE IS NOT A POINT ON A MAP...THE
DANGEROUS EFFECTS OF A STORM CAN EXTEND SEVERAL HUNDRED MILES
AWAY FROM THE CENTER. IF YOU ARE WITHIN THE CONE OF
UNCERTAINTY...YOU COULD STILL EXPERIENCE HIGH WINDS AND HEAVY
RAINFALL...SERIOUSLY IMPACTING LIFE AND PROPERTY.

THE FOLLOWING ARE SUGGESTED ACTIONS THAT CAN BE TAKEN AT THIS
TIME...

CHECK BATTERIES FOR RADIOS AND FLASHLIGHTS. STOCK UP ON DRINKING
WATER AND CANNED OR DRIED FOOD. ENSURE YOU HAVE A MANUAL CAN
OPENER.

HAVE ENOUGH FOOD AND WATER FOR AT LEAST THREE TO FIVE DAYS PER
PERSON. GATHER MEDICINES...TOILETRIES...AND FIRST AID SUPPLIES.

HAVE A SUFFICIENT AMOUNT OF CASH ON HAND SINCE CREDIT CARDS AND
AUTOMATED CASH MACHINES DO NOT WORK WITHOUT POWER.

CHECK FUEL LEVELS ON AUTOMOBILES...GENERATORS...AND CHAIN SAWS.

IF YOU NEED TO MAKE A TRIP TO THE HARDWARE STORE...THE GROCERY
STORE...OR THE GAS STATION...DO SO AS EARLY AS POSSIBLE.

PLEASE VISIT WWW.READY.GOV FOR A MORE COMPLETE LIST OF ITEMS TO
INCLUDE IN AN EMERGENCY PREPAREDNESS KIT.

DETERMINE WHERE YOU SHOULD SEEK SHELTER IF THE STORM APPROACHES
YOUR AREA. CONSIDER WHETHER YOU LIVE IN A POTENTIAL EVACUATION
ZONE. IF SO...IDENTIFY PRESCRIBED EVACUATION ROUTES WHICH LEAD OUT
OF THE THREATENED AREAS. LEARN THE LOCATIONS OF OFFICIAL SHELTERS.
IN ALL CASES...HEED THE ADVICE OF LOCAL OFFICIALS AND COMPLY WITH
ANY ORDERS THAT ARE ISSUED.

MARINERS SHOULD MONITOR THE COASTAL WATERS FORECAST FOR UNSAFE
CONDITIONS. CONSIDER EARLY STEPS FOR SECURING YOUR CRAFT. IF SMALL
CRAFT MUST GO OUT AND CURRENT CONDITIONS ALLOW...DO NOT VENTURE
FAR FROM PORT AND DO NOT STAY OUT VERY LONG. RETURN TO PORT
QUICKLY IF A WATCH OR WARNING IS ISSUED.

&&

.NEXT UPDATE...
THE NEXT LOCAL STATEMENT WILL BE ISSUED BY THE NATIONAL WEATHER
SERVICE IN SAN JUAN AS CONDITIONS WARRANT.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
361. jipmg
there is a surface low based on wind observation over the everglades, winds coming out of the WEST in key west, and out of the EAST in NAPLES

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360. Skyepony (Mod)
The trying to develope low down in the FL straits has stepped off Cuba, moving quick, over the keys. A few west winds can be seen there, blowing up quick. Here's from a buoy on the right side. Looks like it's coming up the west side of Fl.

NFB - Northwest Florida Bay, FL (nfbf1)
Local Time: 1:26 PM EDT on August 15, 2009 Location: 25.08 -81.09 |
Buoy Type: Offshore Tower :
Windspeed measured by: obtained from anemometer

Wind direction (W Dir): South (165 - 174 Degrees)
Wind Speed (W Spd): 19.0 kts (21.9 mph)
Wind Gust (W Spd): 23.0 kts (26.5 mph
)
Atmospheric Pressure (AP): 30.02 in
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Anyone watching that blob SW of Florida take a look at the 12Z CMC from 96 to 144 hours.

12Z CMC

Interesting ...
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Quoting tropicaltank:
We are all focusing on ana and td3 yet something may be brewing in the gulf. Anybody know how the weather is in key west?


Key West Web Cam outside Sloppy Joe's
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Quoting Weather456:
they are literally joined together by a line of convergence

Conjoined twins
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I'm confused and need some help understanding something. I just watched the Tropical floater and saw a swirl emerge from the convection center.
http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

I go to the tropical pages here and see TD 3, and 90L just .5 degrees apart. Are they calling these separate systems? I had thought that 90L became TD3.. can someone help me understand this please?
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353. jipmg
yes we might be talking about a depression soon, TD4 possibly forming in the gulf, there is a definate surface low sucking up cumoulus clouds.
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Quoting Weather456:
they are literally joined together by a line of convergence


Fujiwhara.
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they are literally joined together by a line of convergence

holding hands while cruzin the Atl...lol
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Upper level convergence separates Ana from 03L
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Quoting Weather456:
they are literally joined together by a line of convergence


Cool Pic 456
Member Since: July 17, 2008 Posts: 0 Comments: 347
Quoting Weather456:


is that bills cigar....hahah
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It seems to be happening.
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Quoting mobilegirl81:
I think a depression might be in the making in the Gulf.

Is it the cluster of thunderstorms hitting the Florida Keys.
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Quoting centex:
Anyone else having problems with NOAA GOM imagery?


I was earlier
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they are literally joined together by a line of convergence

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Its building convection over low.
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340. jipmg
that thing over the keys is erupting..
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339. jpsb
Quoting mobilegirl81:
I think a depression might be in the making in the Gulf.
Can't be, the WC said yesterday that was nothing to worry about.
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Quoting CJ5:
Fox news just showed the Ana long term point in Miami. That should generate some buzz.




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TD 3 Storm Relative 16km Geostationary Water Vapor Imagery

Time of Latest Image: 20090815 1515UTC



Storm Relative 16km Geostationary Water Vapor Imagery

To compliment the 16km storm relative TPW product listed above, water vapor imagery, with a spectral weight near 6.7 um is displayed with the same resolution, projection, and storm relative geometry. Water Vapor imagery is helpful in determining the location of deep convection, indicated by the coldest pixels, relative upper-level moisture content in areas devoid of deep convection, and upper-level atmospheric motions via animation of these images. The imagery can be used to infer favorable and unfavorable regions of environmental forcing (e.g., areas of increased vertical wind shear or atmospheric subsidence).
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Quoting mobilegirl81:
I think a depression might be in the making in the Gulf.
We are all focusing on ana and td3 yet something may be brewing in the gulf. Anybody know how the weather is in key west?
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Quoting marinetech47:
If Bill follows Ana and Claudette follows Bill, could the upwelling of cooler waters inhibit Bill and Claudettes growth ?


I don't think Ana will upwell waters too much considering her size and intensity. Bill will likely cause some upwelling.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
334. Relix
She's going N before the forecast. Good for the big islands! =)
Member Since: August 3, 2006 Posts: 0 Comments: 2725
Recon Schedule -
Some dropsonde data would clean up the modelsLink
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332. jipmg
Quoting centex:
Anyone else having problems with NOAA GOM imagery?


nope fine for me
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000
NOUS42 KNHC 151715
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0115 PM EDT SAT 15 AUGUST 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 16/1100Z TO 17/1100Z AUGUST 2009
TCPOD NUMBER.....09-079

I. ATLANTIC REQUIREMENTS
1. TROPICAL STORM ANA
FLIGHT ONE -- TEAL 70
A. 16/1800Z,17/0000Z
B. AFXXX 0102A ANA
C. 16/1530Z
D. 15.6N 56.3W
E. 16/1700Z TO 17/0000Z
F. SFC TO 10,000 FT

FLIGHT TWO -- TEAL 71
A. 17/0600Z,17/1200Z
B. AFXXX 0202A ANA
C. 17/0330Z
D. 16.7N 60.0W
E. 17/0500Z TO 17/1200Z
F. SFC TO 10,000 FT

2. OUTLOOK FOR SUCCEEDING DAY: CONTINUE 6-HRLY FIXES.
A G-IV SURVEILLANCE MISSION IS PLANNED FOR 18/0000Z
WITH TAKEOFF AT 17/1730Z. A FOLLOW-ON G-IV MISSION
IS POSSIBLE FOR 18/1200Z WITH TAKEOFF AT 18/0530Z.

3. REMARK: NOAA43 AND THE G-IV WILL FLY FOUR SUCCESSIVE
RESEARCH MISSIONS INTO AND AROUND ANA DEPARTING FROM
TBPB AT 15/2000Z, 16/0800Z, 16/2000Z, AND 17/0800Z.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.
SEF


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330. jipmg
Quoting HaboobsRsweet:
I hate to say this but I hope Ana clips south FL because if it does it will just be a TS and that is usually nothing more than a bad thunderstorm with a bunch of rain. If it makes it to the Gulf then things get more interesting and more dangerous.


dont understimate 70MPH winds, remember Katrina
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Anyone else having problems with NOAA GOM imagery?
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If Bill follows Ana and Claudette follows Bill, could the upwelling of cooler waters inhibit Bill and Claudettes growth ?
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Thx....keep a good eye on these two...
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Quoting Weather456:
CMC rather bullis taking TD 03 that far north.

Also Ana is in the GOM


The last thing we want. As you said, the GOM waters have nothing to do but warm, and now they're boiling hot.
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Quoting Funkadelic:


Good observation, Ive noticed a WNW movement starting. Dont know if it's a movement or a jog.

In fact on here If you turn on the TROP PTS, you can see that it will be going just north of expected forcast.


Link


Yup.

And it looks like she is having a slight convective comeback (though its still east of the center).
Member Since: July 31, 2006 Posts: 56 Comments: 8112
TD 3 AL032009 - Tropical Depression ANA


Time of Latest Image: 20090815 1615UTC
2km Storm Relative IR Imagery with BD Enhancement Curve





2km Storm Relative IR Imagery with BD Enhancement Curve

The same infrared imagery shown in the earth relative framework is displayed in a storm relative framework, with a 2km resolution and enhanced with the "BD Curve" which is useful for directly inferring intensity via the Dvorak Enhanced IR (EIR) technique. Scaling is provided by two lightly hatched circles around the center. The two circles have radii of 1 and 2 degrees latitude, respectively.
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It will be interesting to see how a faster forward motion for Ana will change her path. Experts, would this likely push her more south or more north and east depending on the steering forecasts?
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I think a depression might be in the making in the Gulf.
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319. CJ5
Quoting Category5hitsNewYork:
If Ana does not strengthen considerably or if it takes a track further south would this divergence possibly keep Bill from making any turns


No
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317. jipmg
Quoting Weather456:


Nope, the tropical near the Florida Keys is an exmaple of where Ana and Bill will be going.


there isnt much room for Ana to go noth as every advisory the track keeps shfiting sotuh.


yes and its crazy, that low over the keys is going from nothing to possibly something
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316. srada
Thanks!

So if they went yesterday, the models runs are more accurate since Ana has formed? correct?..Im still a newbie in this, so please be patient!
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CMC rather bullish taking TD 03 that far north.

Also Ana is in the GOM

Member Since: July 24, 2005 Posts: 407 Comments: 19076
I hate to say this but I hope Ana clips south FL because if it does it will just be a TS and that is usually nothing more than a bad thunderstorm with a bunch of rain. If it makes it to the Gulf then things get more interesting and more dangerous.
Member Since: May 20, 2009 Posts: 0 Comments: 1640

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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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