Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 16:17 GMT le 15 août 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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1914. Drakoen
Quoting jrweatherman:
Drakoen 7:44 PM EDT on August 15, 2009
Quoting Funkadelic:


So Drak, does this mean we will see a model shift tommrow? I think they are over doing the trough. How bout you?


I don't know. They models cannot stay consistent with a forecast for more than a day. Until that happens then you can expect anything.


Drakeon, I read many times yesterday that you were in agreement with the GFS. You believed it had the right handle with with dynamics. Now today you don't know. What changed?


I never said I believed it forecast just only it was more credible given climatology. The problem for me is the lack of daily consistency. My thoughts are not really unchanged as the long-range has little skill.
Member Since: 28 octobre 2006 Posts: 57 Comments: 29922
Quoting Drakoen:
The area in the GOM needs to slow down if it wants to develop significantly.


True. Not sure that it will though as the Easterlies around the Atlantic Ridge are pretty strong. However, even at its current speed, a TD/minimal TS is possible as long as it heads toward the North-Central GOM instead of the Big Bend/Panhandle area.
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and the models keep it south of cuba and all of the other lands
Member Since: 18 juillet 2009 Posts: 0 Comments: 306
1910. RyanFSU
18Z GFDL has Bill has a fish storm, and maybe marginally major -- a very conservative forecast compared to the Hypercane WRF

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Quoting nishinigami:



wow, Bill is smiling again.

Yes he is!
Lol!
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Edit

Hurricane by late Sunday

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Quoting Orcasystems:


Oh I still consider him as a Met, he is just not a certified one. I take them in order of Jeff, Weather456 and StormW... then the rest.
Futuremet is good and Tampaspin. There are many on here that know a lot but are not certified mets.
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Quoting IKE:


And the vorticity has increased this afternoon...



Nice info, Ike. Thanks. Also, check out the visible. Still enough daylight to get a good look.

GOM Vis
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1905. Drakoen
The area in the GOM needs to slow down if it wants to develop significantly.
Member Since: 28 octobre 2006 Posts: 57 Comments: 29922
Drakoen 7:44 PM EDT on August 15, 2009
Quoting Funkadelic:


So Drak, does this mean we will see a model shift tommrow? I think they are over doing the trough. How bout you?


I don't know. They models cannot stay consistent with a forecast for more than a day. Until that happens then you can expect anything.


Drakeon, I read many times yesterday that you were in agreement with the GFS. You believed it had the right handle with with dynamics. Now today you don't know. What changed?
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Mojaibreak LOL
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Quoting fltstorm:


I am a long time lurker on this blog and do NOT post hardly at all, I have to agree, I do the same thing! At the same time taking the necessary precautions for safety first.

Coudn't agree more,I do too.
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1901. NOWCAST
Check Tampa Radar!!!!
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Quoting TampaMishy:
Who is WS?


Your biggest nightmare.
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Quoting Weather456:
hurricAne by late Monday

Maybe by tomorrow night, tonight 50-70MPH at 11.
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Quoting TampaMishy:
Who is WS?
JFV
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Drakeon still expect Bill to hit S Florida like he said?
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Quoting Weather456:
hurricAne by late Monday



Bill reminds me of the Cheshire cat in the loop, talk about evil grin...
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Quoting CaneWarning:


My list is close to yours - Jeff, 456, StormW, Drak, WS...then the rest...


Weatherstudent?

LOL...
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Hard to tell what will become of the wave after bill, but the bill wave looked similar.

Btw for some distraction, this is what im listening rightnow Philosomatika Stream
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Quoting CaneWarning:


My list is close to yours - Jeff, 456, StormW, Drak, WS...then the rest...
Who is WS?
Member Since: 30 juillet 2007 Posts: 0 Comments: 1474
1891. IKE
Quoting MississippiWx:
The wave in the Easter GOM is really starting to catch my attention. Starting to notice some nice curvature in the clouds on the IR loops.

GOM RB IR


And the vorticity has increased this afternoon...

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Quoting Drakoen:


I don't consider him a met either. I consider you a met when you go to college and get your bachelors degree in meteorolgy or a form of atmospheric science.



You're right. He's the quasi-met I mentioned. He knows his stuff allright...but fully trained...nope.
.
He's paid(I guess, which would make him a professional) by the USCG(my thoughts with the troops land and sea), but he's not formally trained as far as I know. I have the same definition as you for what constitutes a fully trained met.
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Quoting Drakoen:


Wow i'm that low on this list. I'm next to weatherstudent. This must be a joke.


Yes its a joke! To me you and 456 are my top two.
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Center of Ana still exposed...though she's trying.
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1887. HadesGodWyvern (Mod)
Ah! A grinning cyclone. That can't be good.
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Oh my. Look at the radar and satellite image for the SW FL area. Is it me or is the tropical wave developing a closed circulation? It definitely looks more impressive than when it was north of hispaniola, must have been the GOM.
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Quoting Ameister12:
We got ourselves a gulf storm!


the caymans and jamaica is in the track now we should keep an eye on the eye of TS ANA
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Quoting palmbaywhoo:
"Given the fact that the LLC has been exposed, I look for ANA to be downgraded on the 5:00 p.m. advisory." from stormw's blog. so orca, before you go poofing, take a second and find out what he said himself, genius


I think Orca may have blocked you.
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1882. Drakoen
Quoting CaneWarning:


My list is close to yours - Jeff, 456, StormW, Drak, WS...then the rest...


Wow i'm that low on this list. I'm next to weatherstudent. This must be a joke.
Member Since: 28 octobre 2006 Posts: 57 Comments: 29922
The wave in the Easter GOM is really starting to catch my attention. Starting to notice some nice curvature in the clouds on the IR loops.

GOM RB IR
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...
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"Given the fact that the LLC has been exposed, I look for ANA to be downgraded on the 5:00 p.m. advisory." from stormw's blog. so orca, before you go poofing, take a second and find out what he said himself, genius
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Quoting Orcasystems:


Oh I still consider him as a Met, he is just not a certified one. I take them in order of Jeff, Weather456 and StormW... then the rest.


My list is close to yours - Jeff, 456, StormW, Drak, WS...then the rest...
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1877. Drakoen
Quoting nishinigami:



wow, Bill is smiling again.


LOL! He has that evil "i'm gonna screw you over" grin
Member Since: 28 octobre 2006 Posts: 57 Comments: 29922
1876. HadesGodWyvern (Mod)
oh wait the text was so small I thought I saw a "h" instead of a "s"
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wow, Bill is smiling again.
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EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 225 NM
ON DAY 4 AND 300 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY


For those who are watching models out past 120 hours - see the above that is posted as part of the forecast advisory. Do you realize that 300 miles is wider than the entire state of florida? That its the difference from Cuba to West Palm Beach? And after day 5 the odds of the track being right are no more than flipping a coin.

Don't panic if you are in the path, and don't think you are off the hook if a model run at 18z on Saturday says it won't hit you next Sunday.

Remember that many people read this blog that don't post, don't be irresponsible and put out false info that could cause people to think that they don't need to monitor the system.

Crazy as it may be, some people reading actually think that a lot of people who post know what they are talking about.
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1873. HadesGodWyvern (Mod)
hmm "A nah" eyeing Louisiana and Mississippi as a hurricane?
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1872. Drakoen
Quoting Funkadelic:


So Drak, does this mean we will see a model shift tommrow? I think they are over doing the trough. How bout you?


I don't know. They models cannot stay consistent with a forecast for more than a day. Until that happens then you can expect anything.
Member Since: 28 octobre 2006 Posts: 57 Comments: 29922
Quoting Drakoen:


I don't consider him a met either. I consider you a met when you go to college and get your bachelors degree in meteorolgy or a form of atmospheric science.




Oh I still consider him as a Met, he is just not a certified one. I take them in order of Jeff, Weather456 and StormW... then the rest.
Member Since: 1 octobre 2007 Posts: 81 Comments: 26511
1870. breald
Quoting MeterologistDewon9:
Floyd was just a big massive storm, didn't make landfall in south carolina but we was on the left hand side of the storm..

And to refresh my memory, someone once told me that if you are on the left side of a hurricane you will get the most rain and wind..is that true?


Yes I believe the east side of the hurricane has more rain and wind than the west side.
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Looking at the models, I think CMC and the Navy might show a little something interesting with Ana in the GOM. Both storms are still weak, but looking at the steering, I think we'll see Bill jog a little south which may impact the currently forecasted turn north.
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We got ourselves a gulf storm!

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Quoting MeterologistDewon9:
Floyd was just a big massive storm, didn't make landfall in south carolina but we was on the left hand side of the storm..

And to refresh my memory, someone once told me that if you are on the left side of a hurricane you will get the most rain and wind..is that true?


Depends on direction and speed. Toward the Carolina's like you mentioned, it would be the northeast quadrant since the storm is headed north/northwest. The storm would be spinning along with forward speed of the actually storm.
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Quoting futuremet:


LOL did not even give me chance to correct it


I wonder how many more will make that same typo! :)
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Quoting caneluver:
Bill is moving @ 17mph. He will beat out the trough!
Quoting canesrule1:
i agree.

I have to disagree because your info is wrong TS ANA is moving at 17mph and TS BILL is moving at 16mph
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Quoting CaneWarning:


:)


LOL did not even give me chance to correct it

please unquote that....I accidentally used foul language.
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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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