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 serialteg:
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 :/


Yup, count me in on those worried. We'll see what happens. I'm prepared for a direct hit from any of those 3 systems just in case. Hopefully we'll be spared once again.
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The 5pm is out.
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1112. jdjnola
Quoting JAC737:
Boom Boom Pow


Boom=Ana?
Boom=Bill?
Pow=GoM disturbance?
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1111. sctonya
NHC 5pm updates are out
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AMSRE

Bill's arm - a fairly well organize system with outer convective rings around a define center

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1108. Fshhead
Quoting TightLines305:


In Doral also


We just got ours a few mins. ago in Kendall..
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Quoting HaboobsRsweet:
surprised at the latest model runs pushing bill so far out to sea. I still have a hard time believing that.


not me! wonder why! :rolleyes:

models = guesses

might as well grab the bookie...
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What is wrong with Ana? Few days ago the center of circulation was to the east of convection... now, it is located to the west of the convection. The storm is an altogether boring one to monitor, as it has not done much but remain in life support. Pre Bill, however, will be a hurricane. No doubt about that.
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1105. Relix
Ana is moving WNW right?
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1104. KEEPEROFTHEGATE (Mod)
Tropical Storm 03L

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

----- Current Analysis -----
Date : 15 AUG 2009 Time : 194500 UTC
Lat : 11:25:54 N Lon : 35:06:30 W


CI# /Pressure/ Vmax
2.5 /1005.0mb/ 35.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.5 2.8 3.2

Latitude bias adjustment to MSLP : 0.0mb

Center Temp : -0.4C Cloud Region Temp : -33.4C

Scene Type : SHEAR (0.15^ TO DG)

Positioning Method : FORECAST INTERPOLATION

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

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************
Member Since: July 15, 2006 Posts: 176 Comments: 55671
Quoting yamil20:
is pouring here in hialeah,fl


In Doral also
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1102. jdjnola
Quoting Weather456:
What bill is doing is building wrapping convection on the back side, setting the stage for convective development at the center.



And at the same time, setting the stage to supply Ana with some more moisture right when she needs it. It almost seems like these two are colluding against us.
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Quoting HaboobsRsweet:
surprised at the latest model runs pushing bill so far out to sea. I still have a hard time believing that.


same here, after it sped it, its location and motion,
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Quoting StormW:


That may have been Humberto...he was close to the TX coast, and before he developed, it was almost dead, then the upper pattern reversed, and bang!


It was Humberto, went to bed as a weak TS and woke up a few hours later to a Cat 1.
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Quoting Relix:


Tell me about it hahaha.

Ha... ha...

I am darn worried XD



121 knots = 139.244313 mph

:/
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Quoting heliluv2trac:
watch the gulf watch ana watch bill when are we gonna get some sleep

We've been sleeping since June 1! It's been a long nap
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surprised at the latest model runs pushing bill so far out to sea. I still have a hard time believing that.
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1094. Patrap
Been dat way a lil while now reed..



991. Patrap 3:04 PM CDT on August 15, 2009

The second Tropical Storm of 2009 Forms in less than 24 Hours in the Atlantic Basin



2009 Storms
All

Active

Year

Atlantic
green ball icon03L.BILL
green ball icon02L.ANA
Member Since: July 3, 2005 Posts: 427 Comments: 129454
1092. jdjnola
Quoting weatherbro:


Wait, a fuigi-wawa affect is happening! Driving Ana more northeast and Bill a bit more southeast? That means Ana could be a fish storm while Bill will cruise the southern Caribbean!


Some of the models had been showing a Fujiwhara effect a few days ago, even though the same models weren't really developing either system beyond TD-strength, which I thought was odd.
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1091. amd
Quoting weatherman874:


Humberto


Humberto unfortunately did develop right before landfall. High Island, TX received sustained winds of 85-90 mph, and an elevated oil platform had gusts well over 100 mph.

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On radar, the Florida disturbance looks like it has an eye like feature.

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What bill is doing is building wrapping convection on the back side, setting the stage for convective development at the center.

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watch the gulf watch ana watch bill when are we gonna get some sleep
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Quoting WPBHurricane05:


Bill is already in the Atlantic.
i mean as in not effecting Florida
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Quoting StormW:


That may have been Humberto...he was close to the TX coast, and before he developed, it was almost dead, then the upper pattern reversed, and bang!

That's the one - thanks Storm! Hope you are able to relax a little this weekend!
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1085. JAC737
Boom Boom Pow
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The tropical wave passing through south florida reminded me of a weak tropical storm ! Perhaps it was because i was centered between two buildings, as when i open my car door, there were fierce winds nearly knocking me to my side. The system so reminds me of Tropical Storm Harvey - weak but nonetheless making the day an interesting one.
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Quoting WindynEYW:
ana water temps from accuweather



from the satellite it looks like it is shear the problem since the llc is expose
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Quoting weatherman874:


Humberto

That's it - thanks!
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Quoting superweatherman:
IMO... Ana is going to hit between Houston Tx to New Orleans Lousiana and Cat 1 or Cat2.....


I notice models are shifting Ana more towards the GOM. Puts me in a predicament because I have plans to head out Monday for a Job near the Gulf coast South of Lafayette. Ahhh, the joys of hurricane season.
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1080. yamil20
is pouring here in hialeah,fl
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guy which one is going in ana first NOAA43 or G-IV and wich one should I look at for decoder message
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Quoting hurricanehanna:
Pat, Taz or Storm - was it last year or the year before, there was a system that formed right off the coast of Texas...A few on here were watching it spin up and luckily it moved inland before it had a chance to develop to quickly - dumped a lot of rain though... there were a lot of doubters though




was that edwourd..?? something like that last year
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Quoting kingzfan104:
Hey, just got in here. So is it just me or will ana go to the gulf and bill to the Atlantic?


Bill is already in the Atlantic.
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Quoting hurricanehanna:
Pat, Taz or Storm - was it last year or the year before, there was a system that formed right off the coast of Texas...A few on here were watching it spin up and luckily it moved inland before it had a chance to develop to quickly - dumped a lot of rain though... there were a lot of doubters though


Humberto
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Hey, just got in here. So is it just me or will ana go to the gulf and bill to the Atlantic?
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1073. jdjnola
Quoting Patrap:
The GOM Screamer riding off to the Nw..




Something wicked this way comes...
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Quoting Tazmanian:
i think that low in the gulf may be come 92L at any time


Do we have any models that are picking up on this yet?
Thanks
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Quoting weatherbro:
Ana could possibly affect Bermuda, While future Bill anywhere along the east coast. It being a moderate traditional El Nino makes me doubt it'll cross Florida into the GOM. It's unlikely, though not unprecedented(remember Andrew).

Now if it goes well south of Purto Rico and such, that's an entirely different story.

Isn't there another invest in back of TD3?


Wait, a fuigi-wawa affect is happening! Driving Ana more northeast and Bill a bit more southeast? That means Ana could be a fish storm while Bill will cruise the southern Caribbean!
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Quoting superweatherman:
is shear going to relax around ANA weather456?


Well 2 models (GFS and ECMWF) that handle shear very well show shear backing off Ana in about 2-3 days. Ironically the GFS still dont develop Ana but explains why the NHC thing some gradual streghtening is possible with Ana.
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Pat, Taz or Storm - was it last year or the year before, there was a system that formed right off the coast of Texas...A few on here were watching it spin up and luckily it moved inland before it had a chance to develop to quickly - dumped a lot of rain though... there were a lot of doubters though
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1067. Relix
Quoting serialteg:
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 :/


Tell me about it hahaha.

Ha... ha...

I am darn worried XD
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Quoting StormW:


Welcome!...and thank you.


Hey storm i just looked at the nhc site still says TD3 is it a td or bill?
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Its Tropical Storm Bill now according to the navy site. :)
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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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