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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Its Tropical Storm Bill now according to the navy site. :)
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ana water temps from accuweather


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HOUR: 126.0 LONG: -63.10 LAT: 19.80 MIN PRESS (hPa): 920.00 MAX SURF WIND (KNOTS): 121.00

something about being puerto rican and this model forecast doesnt like it :/
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Shear is not the problem with Ana. Its dry air.
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CIMSS Animated Satellite...does anyone notice the strange circular concave thing going on in the center of the storm that looks like a contact lens? I don't think that I have ever seen this before.
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I see we have Bill now.. that wave in the Florida Straits looks very interesting, we'll see what happens.
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is shear going to relax around ANA weather456?
Member Since: July 18, 2009 Posts: 0 Comments: 306
i think that low in the gulf may be come 92L at any time
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1054. rxse7en
Strange to see the South to North flow over NE Florida after months of West to East. Guess it's that time of year. :D
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Quoting Patrap:
The GOM Screamer riding off to the Nw..




Maybe not, but that looks ike an eye forming.....?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting Tazmanian:
i think we may have too watch that low in the gulf it looks too me that some in is trying to spin up and fast

I agree Taz...conditions do seem favorable...just no pressure drops as of now
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1050. Relix
Quoting Weather456:


LINK

Thanks a lot, really appreciate it. Will forward to friends and family.
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BILL: New burst of convection firing near where the CoC is around 11N and 34.5W
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1048. Patrap
I believe your 100% correct there Tazaroo.
Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting yamil20:
1029. wunderkidcayman

Thanks

no problem
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GFDL brings Bill to 100 knots

Member Since: July 24, 2005 Posts: 407 Comments: 19076
i think we may have too watch that low in the gulf it looks too me that some in is trying to spin up and fast
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1042. yamil20
1029. wunderkidcayman

Thanks
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found this page useful for models
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1039. Patrap
The GOM Screamer riding off to the Nw..


Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting Relix:
W456... can you point me where this Storm Statement for PR is? I can't find it!


LINK
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting jasoniscoolman10:
two big highs to the north notting going out to sea...hahaha..


Could ya move some of those Blue H's further North and cuve the green dotted lines north too? lol
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1036. KEEPEROFTHEGATE (Mod)
Quoting Patrap:
The second Tropical Forms in less than 24 Hours in the Atlantic Basin


2009 Storms
All

Active

Year

Atlantic
green ball icon03L.BILL
green ball icon02L.ANA
and a third yet to come pat another is just coming off lets see if they can keep up
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Thanks StormW for your update. You have proven to be the voice of calm especially after the long wait for a named storm this year. I think I speak for most by saying your updates are always easily understood even for newbies, and experts alike. Thanks!!
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I think the NHC will keep Ana as a TS with 40mph winds near 14.5N/49.6W at 5pm
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1031. Patrap
Seems Ana's W by WSw Motion kicked the ensemble tracks a lil south a Tad ..
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Quoting wunderkidcayman:

15/2000Z ok so what time is that in edt


4 PM EDT
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Quoting yamil20:



I think they are planning to go out to investigate ana tomorrow,

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



look at For Today (text issued yesterday)
and look at NOTE: 1- THE G-IV WILL FLY A RESEARCH MISSION AROUND
THE REMNANTS OF TD-02 TODAY DEPARTING TBPB 14/2000Z.
2- BOTH NOAA43 AND G-IV WILL FLY RESEARCH MISSIONS
IN AND AROUND THE REMNANTS OT TD-02 DEPARTING TBPB
15/2000Z.

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Tropical Storm Ana


Tropical Storm Bill

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Quoting Funkadelic:


What I ment was, do you think model runs will continue to show a recurvature? Or will they show a track more towards the CONUS and florida like they had been doing for a while?

Thanks for your help, these models just confused me today showing a recurvature, and in my opinion it seems unlikely.


I can say, this early on, since some models show recurvature 8-10 days just ne the Bahamas while some take it into the Gulf. The bottom line is, most have it reaching the Bahamas.

Rather the question is, will it change for the islands.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting superweatherman:
IMO... Ana is going to hit between Houston Tx to New Orleans Lousiana and Cat 1 or Cat2.....


Wrong o!!! guess you didnt get memo.. GOM closed from Corpus to Fl...
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1025. Patrap
TPW&NOGAPS_850_Winds

Member Since: July 3, 2005 Posts: 421 Comments: 127636
if bill dos not turn soon and when it dos turn or if it dos it will make a vary hard turn when it dos
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Meteosat 0 degree Day Microphysics America

The Day Microphysics RGB was inherited from Rosenfeld and Lensky (1998): the VIS0.8 reflectance in red approximates the cloud optical depth and amount of cloud water and ice; the IR3.9 solar reflectance in green is a qualitative measure for cloud particle size and phase, and the IR10.8 brightness temperature modulates the blue. This color scheme is useful for cloud analysis, convection, fog, snow, and fires. In this colour scheme water clouds that do not precipitate appear white because cloud drops are small, whereas large drops that are typical to precipitating clouds appear pink, because of the low reflectance at IR3.9 manifested as low green. Supercooled water clouds appear more yellow, because the lower temperature that modulate the blue component. Cold and thick clouds with tops composed of large ice particles, e.g., Cb tops, appear red. Optically thick clouds with small ice particles near their tops appear orange.
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Plan of the Day

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.

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Quoting wunderkidcayman:

15/2000Z ok so what time is that in edt


1600 EDT I believe.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Link

The Atlantic Lake is like glass here in NC.
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1019. Relix
W456... can you point me where this Storm Statement for PR is? I can't find it!
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1018. yamil20
Quoting wunderkidcayman:

guys talk to me please



I think they are planning to go out to investigate ana tomorrow,

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


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Quoting CaicosRetiredSailor:


Go Here:
http://www.nhc.noaa.gov/

Click on the link on the left side for

"Aircraft Recon"

15/2000Z ok so what time is that in edt
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Quoting stoormfury:
if BILL does not start making that turn at 40w then it will take a dean track of 2007. thru the the central islands
Quoting stoormfury:
if BILL does not start making that turn at 40w then it will take a dean track of 2007. thru the the central islands
Quoting stoormfury:
if BILL does not start making that turn at 40w then it will take a dean track of 2007. thru the the central islands


still the major problem remains that the ridge in 2007 is much stronger than in 2009. I agree that if it does not begin to turn at 40W, then it will likely not follow some of the other models
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Chiggy007:
NAVT site reports BILL with coordinated 11.3N - 34.5W with 1008mb low...


The information given to the models by the NHC was 1004mb.
Member Since: August 23, 2008 Posts: 7 Comments: 5300

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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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