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 tropicaltank:
This seems compatible with the concept of explosive development. Perhaps the concern over the florida keys "blob" was not wishcasting after all.


STORMNO is a troll!!!
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good ole stormy...still don't know a weather system from his...well..you get my drift....but don't go thinking it's just an ordinary ULL as all the experts agree...let me find what an expert saw on this lower keys spin
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711. jipmg
Quoting BradentonBrew:
This "Florida System", just tore the back screen door of the hinges, albeit it was propped open. How fast is the forward speed on this system and is that front pushing to the south going to keep it in the GOM for it to develop further?


the wind is really picking up over here.. I think its..getting stronger
Quoting stormno:
SPECIAL WEATHER STATEMENT ISSUED BY STORMTOPS WEATHER OFFICE 2PM CDT OUT OF NEW ORLEANS LA...

My day is now complete.
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jbsp...

Good points. I used to work with a man, who lost his parents and 8 brothers and sisters in Cameron to Hurricane Audrey. His chilling asccountinclude how he was able to cling to a tree and try his best to breath in a manner , and dodge debris where he didn't drown.

He also said that he was having reoccuring nightmares at least weekly during his entire life afterwards.
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exposed
Nah

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Quoting jipmg:


I have to disagree.. I expect it to be near 15 N by 5 or just on it, it seems its sustaining a somewhat WNW movement

No problem you could absolutely be correct, watch, wait and see, only time will tell.
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Quoting mobilegirl81:
There is something to this system by the keys. Look for the convection to grow alot bigger. If that happens, then we may have a depression forming.


It doesn't matter the size of the convection, it matters on whether it has a LLC, surface low forming. It has better convection than both Ana and TD3. However, Ana and TD3 have low circulation centers. Now, if the key west blob gains a surface low - it could be the bigger story here on the blog.
I believe Ana and TD3 are fighting alot of dry air right now. That seems to be the problem. I don't think either will look good until they get closer to the antilles, caribbean, and bahamas.
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This "Florida System", just tore the back screen door of the hinges, albeit it was propped open. How fast is the forward speed on this system and is that front pushing to the south going to keep it in the GOM for it to develop further?
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Quoting stormno:
SPECIAL WEATHER STATEMENT ISSUED BY STORMTOPS WEATHER OFFICE 2PM CDT OUT OF NEW ORLEANS LA...THE DISTURBANCE OVER THE FLA KEYS HAS BECOME BETTER ORGANIZED AND IS NOW A CLOSED LOW..LITTLE SHEAR IS AROUND THE AREA AND SSP HAVE BEEN FALLING SLOWLY SINCE THIS MORNING NOT TO MENTION THE SST RUNNING 88-92 DEGREES...FOLKS THE LATEST INFO OUT OF MY OFFICE INDICATES TO ME WE HAVE A CLOSED LOW AND ITS DEVELOPING QUICKLY..ALL INTERESTS FROM LAFAYETTE LA TO MOBILE ALABAMA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM..THIS IS A VERY DANGEROUS SITUATION DEVELOPING JUST OFF THE KEYS..WIND GUSTS TO 35MPH HAVE BEEN COMMON THE PAST SEVERAL HOURS..THIS LOW IS FORECAST TO MOVE TOWARDS THE LA COAST AND STRENGTHEN..RAPID STRENGTHING COULD OCCURR..A RECON PLANE IS ON STANDBY AND READY TO GO OUT AND CHECK TO SEE IF BILL IS FORMING ..ITS SCHED TO GO OUT TONIGHT OR EARLY SUNDAY MORNING..A FLASH FLOOD WATCH WILL BE ISSUED SOMETIME TONIGHT OR SUNDAY FOR OUR AREA..FOLKS I CANT STRESS THIS ENOUGH THIS A VERY DANGEROUS SITUATION DEVELOPING AND YOU WILL NEED TO TAKE QUICK ACTION POSSIBLY ON SUNDAY OR EARLY MONDAY..ILL BE BACK AT 8PM WITH ANOTHER UPDATE ON THIS DEVELOPING LOW..PLEASE STAY TUNED TO YOUR LOCAL WEATHER FORECAST AND BE READY TO TAKE QUICK ACTION IF WARNINGS ARE ISSUED LATER..FOLKS I REALLY HAVE A BAD FEELING ABOUT THIS..I BEEN WATCHING THIS AREA FOR 3 DAYS AND ITS STARTING TO GET ITS ACT TOGETHER..ALL THE INGREDIENTS ARE THERE FOR A MAJOR HURRICANE..THIS HAS BEEN A SEVERE WEATHER STATEMENT FROM STORTOPS WEATHER OFFICE IN NEW ORLEANS....Stormno
This seems compatible with the concept of explosive development. Perhaps the concern over the florida keys "blob" was not wishcasting after all.
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Quoting jasoniscoolman10:
tropical storm ana is still moving west at 17 mph. who is saying ana is moving nw is not right.


Its not moving NW, but moving slightly north of due west.
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I won't write Ana off until it becomes an open wave or hits land. Even then, I'll still follow it. This thing has fought since it left Africa.
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Quoting jpsb:
Well since asking about info on that Blob seems to piss everyone of, I'll try to reframe. I lost 4 out of 5 neighbors in Ike, half the homes in my little village are gone, so yea, when something developed in the gulf or looks like it might, I get interested, EXCUSE ME! I'd kinda like a heads up if I need to protect/board up the half a house I've got left.


I understand.... I'm sorry to here about your loses. I know they say this is more of an east coast year, but that doesn't mean we won't get anything. Anything suspicious looking in the GOM bears watching....
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Stormtop.. I'm sorry.. but that was hilarious. Thanks for the laugh today.
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The 5pm advisory should be interesting on these two.
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Quoting WeatherStudent:


It really is, ain't it? And for now, all indications continue to demonstrate a U.S trheat.

True. Usually most of the storms/hurricanes are an eventual threat to the US, unless they recurve out to sea, unless it does a Dean, Emily, or Felix, what about the other little Islands or poor countries that take a real good pounding before it reaches the US. With TD#3 I see track, similar to , Dean 07, Emily05,Gilbert88,Felix07, Charley04 or Ivan04, jmo.
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Quoting Drakoen:
Dry air infiltration continuing to plague 03L


Yea, I guess that's why it is so much more organized now.
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Quoting Catfish57:
Which one Samatha??...Bostwick?


Yep and he was classy enough to eat crow.
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Just an opinion...I feel that the developing system located southeast of the keys will be more than just a rainmaker.
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Getting nasty here in West Central Florida. Swirling winds with minutes of calm. Gonna be some heck of a storms through the evening I guess.
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TD3 starting to look better? What? LoL!! Hasn't looked any worst - LLC is pretty exposed on the east side - convection is not that strong to be honest...
I'll say it again... TD3/Bill will take time to strenghten...for God's sake it's not even a TS yet...
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Quoting jpsb:
Well since asking about info on that Blob seems to piss everyone of, I'll try to reframe. I lost 4 out of 5 neighbors in Ike, half the homes in my little village are gone, so yea, when something developed in the gulf or looks like it might, I get interested, EXCUSE ME! I'd kinda like a heads up if I need to protect/board up the half a house I've got left.



Amen! You are 100 percent correct.
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Quoting kmanislander:


If Ana does not recover soon from her current condition it could dissipate before the Islands. We have to wait and see about that. TD3 is a more serious threat IMO. Further S and with a larger circulation it can fight off dry air better. It is also S of the shear that has undercut Ana's weak convection.

Stay tuned for that one as well. A wait and see game for now.


I realize Ana is undergoing shear, but her circulation is VERY evident. If the shear weakens I see decent intensification in her future.
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Quoting JadeInAntigua:


Have I read it? Yes... However I was asking for an update. Thanks for the helpful reply though.


Well, Ana is looking less dynamic, but will likely pick up again.

TD3 looks like it'll brush the north of the Antilles as a cat 2 by Wednesday.
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Dry air infiltration continuing to plague 03L
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685. jipmg
its getting really windy here in miami
Quoting Samantha550:


Hi Catfish, I am from SE TX too, you may appreciate what I am about to point out. I watch this site alot, its kinda like a hobby for a few months out of the year. Over the years I have learned how to kinda read the models. Just last year on my way home from evacuating from Gustav, a prominent local Met stated a certain storm would never make it to the GOM, and guess what it was IKE. I think that the Met is highly trustworthy and would follow his advice any day. When we are dealing with so many atmospheric variables it is just way too difficult to sat weather a person is "safe" from a storm.
Which one Samatha??...Bostwick?
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It was just an "oops".
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I am out Drak keep them in line. LOL Be back after 5:00 PM
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680. jipmg
Quoting stormpetrol:
Agreed, Ana has wobbled to around 14.5N thats nothing, I suspect it will wobble back & forth from near 14N to near 15N for the next 2-3 days, jmo.


I have to disagree.. I expect it to be near 15 N by 5 or just on it, it seems its sustaining a somewhat WNW movement
679. jpsb
Quoting floridafisherman:

dont forget about humberto, ....
Well since asking about info on that Blob seems to piss everyone of, I'll try to reframe. I lost 4 out of 5 neighbors in Ike, half the homes in my little village are gone, so yea, when something developed in the gulf or looks like it might, I get interested, EXCUSE ME! I'd kinda like a heads up if I need to protect/board up the half a house I've got left.
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678. 996tt
Quoting weathergeek5:


Before Katrina did you really expect a hurricane would do that? How have you changed since then?


My wife still tears up today sometimes. I grab my boards and hit the water when a swell kicks up. Our house was only house in our neighborhood that did not flood during Ivan here in Pensacola on the sound.

There were a bunch of tractor trailers parked that became missles in Biloxi. We kept a copy of the insurance policy and got back in the next day and unfortunately seeing bodies and the stench stays with you. Stuff can be replaced.
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TD 3 has become much better organized today, and once the convection starts firing I wouldn't be surprised if it was 50 kt by tomorrow.
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Quoting Catfish57:
Back in 2007, I went to bed with a TD in the Gulf, and when I woke up, I had a hurricane. (Humberto). I also am old enough to remember Camille. Back in those old chalkboard days, forecasting was much tougher. I can remember the weatherman drawing a cone from Houston to Tampa. That's how unsure they were. And even today GOM 'canes can be the most unpredictable of the lot


Hi Catfish, I am from SE TX too, you may appreciate what I am about to point out. I watch this site alot, its kinda like a hobby for a few months out of the year. Over the years I have learned how to kinda read the models. Just last year on my way home from evacuating from Gustav, a prominent local Met stated a certain storm would never make it to the GOM, and guess what it was IKE. I think that the Met is highly trustworthy and would follow his advice any day. When we are dealing with so many atmospheric variables it is just way too difficult to sat weather a person is "safe" from a storm.
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Quoting thelmores:


thelmores is thinking another tropical low could form in the EATL.....

Hey ya'll look at that! Me and the NHC agree! LOL


syllogism
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Kman, Agreed. I really havent heard anyone talk about the ridge that is supposed to build mid next week. Thought I would throw that in the mix.
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More errands to run so out again for a while.
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Quoting CJ5:


You cannot call PR spared at this point, that is misinformation and there has been no considerable movement N by Ana in the last 5 hours.


word cj5. you go girl (or dude)

isnt cj5 a jeep?
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Quoting lakeEFX:
Most people on here are smarter than me when it comes to the tropics, and I know that Dr. Masters is WAY, WAY, smarter than me. But one thing I DO know is that Hurricane Andrew was NOT named on August 17, 2009. (check the blog). LOL! I'm sure it was a typo- seeings how everyone's caught up in the excitement of finally having our first named storm.


Am I missing something. Can you name something in the future (August 17th, 2009) and Andrew isn't a name on the list this year?
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Quoting serialteg:


The blog was uploaded like, an hour ago? Somethin like that... Pretty much a good update, considering these things are days from land


Is is really necessary to be so rude?
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Quoting CJ5:


You cannot call PR spared at this point, that is misinformation and there has been no considerable movement N by Ana in the last 5 hours.
Agreed, Ana has wobbled to around 14.5N thats nothing, I suspect it will wobble back & forth from near 14N to near 15N for the next 2-3 days, jmo.
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667. jipmg
Quoting stormpetrol:
TD#3 is really coming together now, probably "Bill" at 5pm , if not 11pm the latest, that is one large circulation. I have a feeling that is going to be one significant hurricane.


there is some convection firing now that the sun is starting to set over there near africa lol
Quoting ClearwaterSteve:
How's it Kman. I agree with you concerning Ana. I say she breaks up through the islands or just north of them. Also TD3 will find a ridge weakness and escape to open water.

Thoughts


If Ana does not recover soon from her current condition it could dissipate before the Islands. We have to wait and see about that. TD3 is a more serious threat IMO. Further S and with a larger circulation it can fight off dry air better. It is also S of the shear that has undercut Ana's weak convection.

Stay tuned for that one as well. A wait and see game for now.
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665. Relix
Quoting CJ5:


You cannot call PR spared at this point, that is misinformation and there has been no considerable movement N by Ana in the last 5 hours.


I am always an optimist =P
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Quoting wxfempilot:
Sorry guys - I'm still new to the link process - this is a streaming cam, so the pic may be different from what I saw - Chesapeake Resort in Islamorada -it was dark and blowing hard a moment ago - the Keys cams are a good indicator that it looks like something that'll blow over - for now. But in the GOM? No Opal, obviously, but a good rainmaker.

Link


seems like people are NOT in the beach area :D
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.