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 JupiterFL:


If you stopped posting and looked around the site you could find it.


Been here for so long and still doesn't know how to get to the ECWMF
Member Since: October 28, 2006 Posts: 57 Comments: 30577
ok for real......is the "keys wave" something we on the gulf have to worry about or is it just going to be a rain maker?
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Quoting Drakoen:
Did anybody's roof come off yet that lives in the Keys?

My Cosmo tipped over, all over my pants no less.
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Quoting atmoaggie:

LOL!
Back later. Replacing all my windows with permanent steel doors. (j/k)


You are putting steel doors on your windows????

Sounds intelligent!
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the weakness of both systems ana and td3 should allow them to go ith the east to westflow and follow a trck north of due west. in that way the models could be way off. time will tell
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The keys system makes Ana look like a fart.
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Link UPDATED BLOG,just updated my expert blog on tropics td3,and ts ana.
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Quoting WeatherStudent:
Guys, may someone plz give me the link to the latest ECMWF Model input?


If you stopped posting and looked around the site you could find it.
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Quoting Drakoen:
Did anybody's roof come off yet that lives in the Keys?

Has Ana hit 50 mph yet?
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Quoting southfla:
seflagamma, Dr. Master's wording made perfect sense to me :-) I understood exactly what he meant.

it seems dr. masters reasoning does not mean anything to certain people. to them, if he would not say anything would be perfect to them.
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Did anybody's roof come off yet that lives in the Keys?
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting Catfish57:
Nice piece of history South Fla...

But I got a question for you Super Mets here. What are those 2 1/2 boxes that are located jutting SSW from the storm (on the map) during it's mid course?


I believe those are Herbert Boxes:

A Hebert box (pronounced AY-bear, also known as Hebert's box) is one of two regions of the tropical Atlantic Ocean that are useful as predictors of hurricanes that will strike South Florida, USA. They are named for former National Weather Service and National Hurricane Center forecaster Paul Hebert, who observed in the late 1970s that most strong hurricanes (characterized as those with winds exceeding 110 miles per hour (177 km/h)) which had struck South Florida since 1900 had also passed through one of these two small 335-mile-by-335-mile (517-km-by-517-km) square geographic regions.[1]

Examples include unnamed hurricanes in 1926, 1928, 1933, and 1935, as well as the major hurricanes Donna and Betsy, all of which came through a Hebert box. Collectively these storms killed more than 2,000 people in Florida. Conversely, storms such as the major hurricanes Floyd and Gert in 1999, which both were headed for Florida at one point, missed the Hebert boxes and turned away from Florida at the last minute.[1]
(from Wikipedia)
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802. CJ5
Quoting WeatherStudent:


Who cares about her, she's bond to be a fish, anyways.


You pretty much have to have a smartarsed remark for Drak everytime he posts, don't you? Why is that? It would be refreshing to everyone on the blog if you would stop.
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Member Since: July 3, 2005 Posts: 426 Comments: 128866
Quoting jurakantaino:
Serialteg Watch out , we may get hit by one of the two,systems or by both,"Ponce is Ponce the rest is parking"..


Hopefully by neither, altough I do wish they come by either the north or south so as to get my surf on...

you know what? ponce IS ponce. in fact, anywhere BUT the metro area (and mayaguez) deserves to be proud. lived in the metro 25 years (all me life) and one year here, and the quality of life is much better (no traffic) (light and water almost never are out, metro its a weekly event)

so yeah, ponce IS ponce!
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Quoting Drakoen:
ECMWF now forecast for another system to develop in the tropical Atlantic.


CAN YOU BE A LITTLE MORE VAGUE?

I wanted to agree with that too, but didn't have enough specifics! LOL
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797. 996tt
Quoting PcolaDan:


Do I detect a note of sarcasm here? :) lol
I could actually hear the inflection.


We better close our storm shutters or board our houses up.
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796. Relix
I simply do not believe or see a way for Ana to go the NHC track. I am expecting it to enter the caribbean in all honesty, maybe reaching Cuba or Haiti, but I really, really, reaaalllly don't think it will follow the current track. In fact I give the track a 30% of happening
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so by next wednesday we should know where the storms are going?
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Quoting LightningCharmer:
I just talked to guy that watched his favorite lawn chair blow away. These gusts are no laughing matter.


That was hilarious. I brought all my lawn chairs in. My porch door not so lucky.
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Quoting WeatherStudent:


Who cares about her, she's bond to be a fish, anyways.


How do you know? It's not even off Africa yet.
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Quoting BradentonBrew:


You may be sarcastic, but I already have a screen door to replace from a higher gust. Your melodramatic undertones aren't helping the situation.

You should have secured it. What the other buffoon is trying spray us with is a situation where you would have to replace a bunker.
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Quoting rxse7en:
True dat. I personally don't care about policing the blog, but when it comes to his "Official" statements I have a problem. There are people on here that come here for guidance and ST's posing is not only dangerous, it's illegal.


I highly doubt that its illegal. He's been around since the beginning and it adds a little humor. We all need that when a storm is headed in our general direction. At least he doesn't post non stop crap like some others on this board.
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If Ana reaches the DR/Haiti, it will decrease her strength significantly!!
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Ana will pass south of 15N at 50W. So watch S cone.
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Quoting atmoaggie:

LOL!
Back later. Replacing all my windows with permanent steel doors. (j/k)


LOL
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.
I just talked to guy that watched his favorite lawn chair blow away. These gusts are no laughing matter.
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Quoting WeatherStudent:


Who cares about her, she's bond to be a fish, anyways.


The ECMWF take it into the Caribbean
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting hunkerdown:
I am thinking a little further south, not necessarily buying into the sharper curve out to sea.


hmmmmm, I have been kinda wondering about that too...
Member Since: July 2, 2009 Posts: 0 Comments: 2811
seflagamma, Dr. Master's wording made perfect sense to me :-) I understood exactly what he meant.
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Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.

LOL!
Back later. Replacing all my windows with permanent steel doors. (j/k)
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Wouldn't be surprised if the NHC keeps Ana at a conservative 35 knots. The intensity forecast is gonna be real tough with wind shear, dry air, and Hispaniola.
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Drak- I agree! Dry air is hurting both systems.
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Quoting hunkerdown:
is it safe to come out yet (I am typing from an interior bathroom under two mattresses.


No it's expect to stall their for the rest of your life!
Member Since: October 28, 2006 Posts: 57 Comments: 30577
Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.


The casualties...oh the humanity!
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what is going on with the trough next week is it going to be weak or strong
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Nice piece of history South Fla...

But I got a question for you Super Mets here. What are those 2 1/2 boxes that are located jutting SSW from the storm (on the map) during it's mid course?
Member Since: July 29, 2009 Posts: 0 Comments: 72
Serialteg Watch out , we may get hit by one of the two,systems or by both,"Ponce is Ponce the rest is parking"..
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Quoting jurakantaino:

Isn't it suppose to go wnw and reach latitude 18n 66w by Monday?

Very often in my years of watching storms, they often don't do what they were suppose to do.
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Quoting LightningCharmer:

My day is now complete.


Someone ban him. (Stormtop)
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Quoting seflagamma:
Ana is the latest first named storm of the season since Hurricane Andrew got its name on August 17, 2009

OK folks, the above from Dr Master's header... It is a TYPO people..
the world is not coming to an end over that typo..
any of us here with any weather knowledge remembers Andrew and it was 1992.
If you do not see the innocent typo error and keep on harping on it..get a life.



Give Dr Master's a break please.


Leave Dr. Masters Alone - ish link
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Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.
is it safe to come out yet (I am typing from an interior bathroom under two mattresses.
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Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.


Do I detect a note of sarcasm here? :) lol
I could actually hear the inflection.
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Quoting TexasHurricane:


What are you thinking? Thinking it will start to go more south or north?
I am thinking a little further south, not necessarily buying into the sharper curve out to sea.
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Quoting Drakoen:
Deadly Catastrophic 20mph winds racing through the Keys.


You may be sarcastic, but I already have a screen door to replace from a higher gust. Your melodramatic undertones aren't helping the situation.
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With each model run things look better and better for S Fla!
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Quoting atmoaggie:

Dude, do you have to quote the whole thing?
True dat. I personally don't care about policing the blog, but when it comes to his "Official" statements I have a problem. There are people on here that come here for guidance and ST's posing is not only dangerous, it's illegal.
Member Since: Posts: Comments:

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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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