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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2564. jipmg
Quoting Relix:
What's Ana's current movement? W? Or WNW?


In between , just north of due west
2563. szqrn1
Quoting ssmate:

What happened with the Tux picture? I actually miss that one.


I think thatwas his prom pic from last year!..seriously!
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I THINK MODELS WILL SHIFT A IT MORE TO THE SW WITH BILL. HE IS MOVING RIGHT KNOW JUST SOUTH OF DUE WEST AND HIS POSITION IS A VERY DANGEROUS ONE FOR PUERTO RICO AND SOUTH FLORIDA. I AM NOT BUYING THE SOLUTION OF IT GOING OUT TO SEA.
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Quoting eye:
4 years plus getting a degree vs certification, huge difference....there are alot of reasons why you cant go to college, but that is also what student loans are for...lots of people go to college to get the degree and then have huge student loans to payoff, but the prize is a degree you can hang on the wall in your office....


yes and no. it all depends on the field and the situation. salaries are usually higher for those with degrees in most fields. let's put it this way: having a degree doesn't hurt
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2559. IKE
Quoting cajunkid:
I didn't want to hear that Ike...here we go. Watch NOLA freak out tomorrow am


It's lacking low-level convergence though...

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Quoting HurricaneRoman:
Hey everyone! Its been over a year since i last posted on here. Is bill gonna be curve out to sea before making it to the U.S.? the new models seem to show a turn to the nw



way too soon too tell the modes runs can not get a good fixs right now on it so the best we can do is this wait see and watch how thing play out
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Quoting presslord:
OK...the image of JFVWS in the bathroom is far scarier than any tropical weather system...

He was looking for the circulation! lol j/k
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Quoting stormbottom:

got it triple clipped and strapped and foamed in all the really long screws ! house is old though..and your welcome Fisky !

just to let you know that with all those straps, etc. your house is more liable to be struck by lightning. was told this by a captain for a fire dept. number one cause of lightning strikes on houses.
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Quoting victoriahurricane:
Mostly a lurker here, but it looks like we could have a repeat of the picture Pat took in 2008 with 4 named storms all at once. What happened to El Nino? And the Africa wave train just keeps on giving. Atlantic is going nuts.



I posted a comment earlier today indicating El Nino may have peaked in late July. Waters have not warmed during the first half of August.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Drak, what do u think of Bill's eventual track?
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Quoting midgulfmom:
class='blogquote'>Quoting stormbottom:

got it triple clipped and strapped and foamed in all the really long screws ! house is old though..and your welcome Fisky !

Stormbottom, you are good ta go! My house is old too, about 100yrs old. But that's how I like'em.
Action: Quote | Ignore User

from your keyboard to gods ears !! thunder and lightning stopped here now..going to hit the stores first thing tommorrow and get it all over with !
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Currently all models take this NW, how about wait till this moves West, jeez, might mean, SFLA is in danger if it continues WSW motion, imho,
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2551. ssmate
Quoting presslord:
OK...the image of JFVWS in the bathroom is far scarier than any tropical weather system...

What happened with the Tux picture? I actually miss that one.
Member Since: July 17, 2008 Posts: 0 Comments: 347
Quoting StormW:


I will be in tomorrow afternoon around the same time, about 3-4ish
Thanks for the weekend updates since you don't do them normally. Greatly appreciated.
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this is for bill it looks to me that we may have a strong TS in the next update at lates 60mph or so raw T # is up too 3.5




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

----- Current Analysis -----
Date : 16 AUG 2009 Time : 011500 UTC
Lat : 11:16:17 N Lon : 36:09:47 W


CI# /Pressure/ Vmax
3.2 / 997.6mb/ 49.0kt


Final T# Adj T# Raw T#
(3hr avg)
3.2 3.4 3.4
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Hey everyone! Its been over a year since i last posted on here. Is bill gonna be curve out to sea before making it to the U.S.? the new models seem to show a turn to the nw
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I didn't want to hear that Ike...here we go. Watch NOLA freak out tomorrow am
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The no-gaps just wont concede will it?
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2521 LOL
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2543. Relix
What's Ana's current movement? W? Or WNW?
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2542. DDR
Quoting Weather456:


What the heck


Every one take a look at Bill's 18Z Models. How the heck is Bill going to go straight NW from its current position. It's not even going west.


These models need to wake up and smell the roses.


It's not going west? is it wsw?
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why have the models called for ana to drop south rather then the northern motion depicted earlier?
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class='blogquote'>Quoting stormbottom:

got it triple clipped and strapped and foamed in all the really long screws ! house is old though..and your welcome Fisky !
Stormbottom, you are good ta go! My house is old too, about 100yrs old. But that's how I like'em.
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I never said I trusted the Bill models...I will believe the revurve forecast when the storm stops moving WSW at 17mph... I'm thinking just north of PR, then through the Bahamas at least. It's gonna get pretty strong, so it's not likely to continue going WSW...it will turn to the north, just not as quickly or sharply as predicted right now.
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2525. BILOXISAINT2 2:05 AM GMT on August 16, 2009
Quoting mobilegirl81:
Gulf coast, do not be surprised what you wake up to in the gulf tomorrow.
Girl I so hope you are wrong


gotta feeling your right ....been watching this all day also...people around here will freak...
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2536. jipmg
Quoting Weather456:


What the heck


Every one take a look at Bill's 18Z Models. How the heck is Bill going to go straight NW from its current position. It's not even going west.


These models need to wake up and smell the roses.


yea I agree.. also if bill is turning NW immediately due to a weakness in the high, then why is ANA forecasted by the models to track W to WSW?

In any case, models are spreading a bit for ana, and still in consensus that BILL is turning into a fish storm despite its continual W-WSW movement. Although two models anticpate it moving over the northern antilels.
Mostly a lurker here, but it looks like we could have a repeat of the picture Pat took in 2008 with 4 named storms all at once. What happened to El Nino? And the Africa wave train just keeps on giving. Atlantic is going nuts.
Member Since: Posts: Comments:
Quoting Weather456:


What the heck


Every one take a look at Bill's 18Z Models. How the heck is Bill going to go straight NW from its current position. It's not even going west.


These models need to wake up and smell the roses.



456, do not know if you saw my post earlier, but I am glad you are prepared for whatever Ana and/or Bill may bring.

Quoting leftovers:
really stepped it up thanks


Clarification please? I do not understand what you mean by "really stepped it up"
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2533. szqrn1
Quoting BILOXISAINT2:
Girl I so hope you are wrong


I am in gulfport.. I also hope you are wrong!

Any experts here think it has time to develop??
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2532. Skyepony (Mod)
Quoting canesrule1:
WNW
---------------------------------------------------

Bill looking impressive:


Bill still looks like a smiley face..
Member Since: August 10, 2005 Posts: 162 Comments: 37829
Quoting Weather456:


What the heck


Every one take a look at Bill's 18Z Models. How the heck is Bill going to go straight NW from its current position. It's not even going west.


These models need to wake up and smell the roses.

yup
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Quoting AussieStorm:

StormW's latest Blog

WOw- thanks Aussie - he is staying busy!
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2529. Drakoen
If Bill is intensifying now as the quickscat and objective guidance suggests, it will start moving to the WNW.
Member Since: October 28, 2006 Posts: 57 Comments: 30489
Anyone notice there's a 91L now? http://www.nrlmry.navy.mil/TC.html
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2526. eye
4 years plus getting a degree vs certification, huge difference....there are alot of reasons why you cant go to college, but that is also what student loans are for...lots of people go to college to get the degree and then have huge student loans to payoff, but the prize is a degree you can hang on the wall in your office....
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Quoting mobilegirl81:
Gulf coast, do not be surprised what you wake up to in the gulf tomorrow.
Girl I so hope you are wrong
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Quoting CatastrophicDL:

Many companies consider (and substitute) military training for college degrees. I'm sure they don't do this just for giggles!

many college degree people look down on military trained people, no matter what kind of training they get while they are in the military. i know a lot of military trained people who know as much or more then a civilian.and the coast guard has an more invested interest in the weather considering what they are tasked for. if stormw makes a mistake, it could cost lives.
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2523. Skyepony (Mod)
Looks like a dropsonde failure on the SW side, outside of Ana.
Member Since: August 10, 2005 Posts: 162 Comments: 37829
Weather Student- I really believe there is something wrong with you. Betcha forgot your meds today.
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OK...the image of JFVWS in the bathroom is far scarier than any tropical weather system...
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Quoting rxse7en:
I can't read the bottom line, is that Bill?


Yeah.
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Quoting hurricaster:
Thoughts on the direction of 91L?
WNW
---------------------------------------------------

Bill looking impressive:
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2517. IKE
91L has a high over it...




Increasing vort on the 0000UTC frame...

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Radar is very interesting to me. Very impressive.

91L Tampa Radar
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Quoting kmanhurricaneman:
give him an A... go to the head of the class!


that wasn't nice
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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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