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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Member Since: July 24, 2005 Posts: 407 Comments: 19076
263. jipmg
Quoting Ameister12:

You sure?
Ana is still completely exposed.


convection is trying to blow near the center, well to the east of it, its not being blown off too much, slight to moderate shear blowing over head keeping it from organizing, I suspect at DMAX it will come back
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I'm new to this blog but I find the comments so interesting, especially when we have so much activity in the Atlantic. I live in Barbados and it seems we are in the clear at the moment(as usual). My prayers for those in the northern territories. Ana may be a TD soon again, but all eyes on BILL the monster.
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Quoting Weather456:
preparations are almost completed


Where do you live again? And smart you, getting ready.
Member Since: December 21, 2007 Posts: 13 Comments: 3044
Quoting Patrap:



Gee WS,now Im awake now,! Im gonna nee a few moments to Wipe my Laptop screen clean ...ke..bu


I am not WS....
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting calcalla5678:
Does anyone think it is likely that Ana or Bill will hit in the Biloxi-Pascagoula-Mobile-Pensacola region?


Really kind of early for that narrow a cone. Wait and we shall see. sorry but its kind of the theme with these things.
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Quoting futuremet:
Close up
Image and video hosting by TinyPic

img src="Image and video hosting by TinyPic" alt="" />



Gee FM,now Im awake now,! Im gonna need a few moments to Wipe my Laptop screen clean .....
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Quoting futuremet:
Close up
Image and video hosting by TinyPic

img src="Image and video hosting by TinyPic" alt="" />


Not loving that at all. Luckily (hopefully) they will change many times still.
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I made a quick update because I have to leave, check it out!
Link
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Dont become too focused on any particular Model run as they will change from Run to Run.

Best to keep the Big Pic in view and take this Grace of time to prepare your Supplies and ready ones family Plan in case ACTION is required next week,or earlier in the Islands
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Quoting chevycanes:
Ana is trying to bring the convection closer to her center.

You sure?
It's still completely exposed.
Member Since: August 9, 2009 Posts: 10 Comments: 4907
252. hamla
SAME SORRY
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251. jipmg
Bill looking like its no longer moving WSW
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Does anyone think it is likely that Ana or Bill will hit in the Biloxi-Pascagoula-Mobile-Pensacola region?
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Quoting mobilegirl81:
Is there a low trying to develop at the tip of Florida?
I believe there is a low developing.If so it could really pop,considering how hot the gom is at present.
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Quoting Patrap:
GFS + 144hrs


Seems like TD3 will make it into the gulf after all... sighs.
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Hey thanks for the update. Where can I find 7-14 day satellite loops of the Tropical Atlantic. Can anyone help me please?
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246. srada
Good Morning everyone!

Tropical Storm Ana has finally formed! Does anyone know or can provide when the first recon flight will be? Many thanks in advance
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Close up
Image and video hosting by TinyPic

img src="Image and video hosting by TinyPic" alt="" />
Member Since: July 19, 2008 Posts: 43 Comments: 4051
244. hamla
WHAT IS INVEST 90 THAT SHOWS UP WITH SANE CORD. AS TD3??
IS IT THE BIG ONE JUST ABOUT TO COME OFF AFRICA AS SEEN IN SAT.PICS???
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243. CJ5
Yep, Ana's center is moving away or should I say her convection is getting blown back. Looks like 'Ole Ingrid.
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ana is wetting their environment, we shall soon see a healthy system
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Quoting Weather456:
Ana could enter the Gulf of Mexico

I agree with you there...I have been thinking south FL or Gulf all along. i am afriad the models will do the same with td3 and start to trend to the south making it more of a reality that it also has a shot to head into the Gulf. Could be a long week ahead of us.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Quoting melwerle:


Thank you!!! Just sent it out to my friend...


Feel free to post My Prep ENtry anytime,thats what its there for,TY
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Quoting melwerle:


Thank you!!! Just sent it out to my friend...


Your welcome
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Quoting P451:


That took me to the 00Z NGP Pat, the 12Z GFS just popped out.


Like I said below,or above,..Im not awake yet,we were up to 3:30 am CST for the ANA upgrade,wanna see what I posted then..?
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Quoting tbrett:


Don't know if anyone answered you but Patrap's Blog Hurricane Preparation gives really good info. From that I took the link to the Supplies list

Link


Thank you!!! Just sent it out to my friend...
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Ana could enter the Gulf of Mexico
Member Since: July 24, 2005 Posts: 407 Comments: 19076
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Quoting presslord:
maybe I'm just trying to read tea leaves here...but...Dr. Masters' Andrew analogy is somewhat disconcerting...



Sure is Press,and My Boca Raton Source seems to agree
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Quoting presslord:
maybe I'm just trying to read tea leaves here...but...Dr. Masters' Andrew analogy is somewhat disconcerting...

Yes, yes it is.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
preparations are almost completed

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting mikatnight:


Thanks Aussie, but I think you're just jealous! I've never been first to post before and I wasn't even trying. I even posted "new blog!" in the old blog before I posted in the new...how exciting! I've already told my wife three times, "Honey, I'm #1!" "You're easily amused", she said, and went back to her hurricane preparation list.

A prophet is seldom honored in his own house....
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maybe I'm just trying to read tea leaves here...but...Dr. Masters' Andrew analogy is somewhat disconcerting...
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Is there a low trying to develop at the tip of Florida?
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GFS + 144hrs
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TD3 is trying to wrap the bands to its south around its center. Drier air seems to be impeding development on its northeast quad.
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Quoting BiloxiGirl:
Futuremet! Where the heck did that come from?? Not cool.


I agree!!! I live in the Pass....
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Quoting canesrule1:
yup, it is completely exposed.


Children, cover your eyes! She's naked!
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Quoting P451:
12Z GFS 168HR

What you see:

Ana as a tiny bump to the west of TD3 slowly fall apart as it tracks towards Hispaniola.

TD3 becoming Bill as it heads through the northern islands.

The African wave developing into Claudette as it follows TD3/Bill.

the c will make it 3 that will be enough for august then we get ready for sept
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219. 7544
Quoting chevycanes:
Ana is trying to bring the convection closer to her center.


looks like ana and td3 are fedding from one another anna might be full soon
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Quoting Patrap:
NEXRAD RadarKey West, 1 Hour Running Surface Rainfall Accumulation Range 124 NMI



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OK and that'll leave you and 4 other bloggers remaining... thats fine by me
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Futuremet! Where the heck did that come from?? Not cool.
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Ana is trying to bring the convection closer to her center.
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Quoting melwerle:
I have a friend who doesn't have their hurricane kit together...can someone send me a link to a place that has a list of everything you need in one? I will link it up and forward it to her.

Thanks, Melissa


Don't know if anyone answered you but Patrap's Blog Hurricane Preparation gives really good info. From that I took the link to the Supplies list

Link
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Quoting AussieStorm:
Goodnight all,
Stay safe, play safe, blog safe, and do what you need to do now to prepare before its to late.
Cheers AussieStorm

P.S
Its ment to be 30c in parts of Sydney today (Sunday).


G'night.
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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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