Ana and TD 3 take aim at the Lesser Antilles

By: Dr. Jeff Masters , 04:17 PM GMT on Αύγουστος 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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if tonites quikscat hts 91L that should tell us how organized it is at the surface.
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Here are the 18z models interpolated to the current position:





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Another thing.....

Do not get too focused on Bill, as Ana could sneak up on you, and it is also a couple of days ahead of Bill. Just an observation, as some bloggers have put Bill ahead of Ana, when it is the opposite.
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no all indications are this is a florida/ala/Miss storm.. its moved clearly more North of West and looks like it will be grazing Western Florida as it goes up.. Tx definetely is out of the woods with this one.. not that thats what they want since they need the rain
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weather456 you think 91L will be a TD by morning or even a TS by tomorrow afternoon since it will be a good time in the water
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Quoting nrtiwlnvragn:



thats not good and 91L is not moveing that march has well this could go too 91L toa strong TS in no time
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2458. Melagoo


Wow Bill is Billowing!!
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Quoting TexasHurricane:


so it is suppose to go towards LA not the Florida panhandle?
give him an A... go to the head of the class!
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Interesting trends with the models. 3 of them now take Ana SOUTH of the Caribbean islands, 1 takes them OVER the islands, and 1 takes Ana NORTH of the Caribbean islands. I would expect another shift slightly south at 11 from the NHC, more in conjunction with the UKMET, GFDL, as well as the NGFDL. The GFS does not even initialize the storm, and it also appears the HWRF dissipates the storm over the islands, and the NOGAPS seems to be the northern-most model solution. JMO, but I would think another shift south in the track could be in order at 11. A Caribbean track would not be good, as the TCHP is very high, and could produce rapid intensification of Ana if it were to traverse those waters, if it were to encounter a favorable upper air environment while passing south of the Caribbean islands. Just speculation, however.

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current full wundermap radar loop

radar presentation very impressive...

i think if it had more time this could be very dangerous...

but bc of where it is at already and the speed its moving i dont think itll have enough time to bedcome more than a moderate to strong ts...
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Quoting weatherfan92:
I guess the "F5" madness will be starting in about in hour.
In an hour? Im doing it now!
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Quoting TexasHurricane:


so it is suppose to go towards LA not the Florida panhandle?


They have only run the BAMs models so far, thats what it shows. An update with additional models should come out, but I don't know how soon.
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2451. snotly
91L might not amount to much but I remember TD10 when we were in FL on vacation one year. Man! was it windy! Tornado warnings all night long too.
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hi all ,FEMA guy here ,you are doing an excellent job leting know people about weather ,very professional way on tracking stoems ,,,btw i ll get my cal in duty pertty soon ,thanks
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oh yeah the boomers have started. where you at in brevard?
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Does anyone know how to post a pic from the WunderMap?
Member Since: Ιούλιος 14, 2009 Posts: 51 Comments: 1731
Quoting nrtiwlnvragn:


so it is suppose to go towards LA not the Florida panhandle?
Member Since: Ιούλιος 2, 2009 Posts: 0 Comments: 2811
man i go away and have dinner and we now have 91l. Tropics are going nuts.
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2445. IKE
Shortwave IR of 91L....




Shortwave IR of Ana....

Member Since: Ιούνιος 9, 2005 Posts: 23 Comments: 37858
2444. geepy86
Wow, pretty good storm here in n. brevard.
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91 may have a "weak" surface circulation at best.....

but it seems to me, this would be the next step in organization, IF there is going to be any.....

the good news, 91 does not have a lot of time to organize prior to running out of liquid real estate.....
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2441. jpsb
Texas Hurricane, I don't have a clue (surface low either) time to get a sixpack and wait for someone with a clue to post. These gulf storms are very hard to predict. But it appears this one is heading for open water. Since I live right on Galveston Bay I'd better paid attention this PM so I'll know what I need to do (if anything) tomorrow AM.
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2440. sngalla
Quoting tropics21:
and they work take it from me mine were tested and came through with flying colors two years ago


Thanks! Nice to know!
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Can someone post a good picture of Bill please??
Member Since: Ιούλιος 2, 2009 Posts: 0 Comments: 2811
Quoting jipmg:
yikes ana not looking good, the shear is having its effects, Bill on the other hand...


Looking better than earlier, do not give up on it.
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2437. jipmg
Quoting SELAliveforthetropic:

If so, I would have enough time to become a hurricane


no 91L isnt near tropical storm strength, there is barely a surface circulation
Quoting jipmg:
yikes ana not looking good, the shear is having its effects, Bill on the other hand...


Why yikes? You don't want Ana to get stronger do you?
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2435. Grothar
Quoting Weather456:


its rather a waste of blog space it such a time info needs to be communicated.

IMO, I have been saying this since Bill was 90L. Tracks are going to shift as along as it does two things:

continue west

speed up


Bill is now moving wsw or 260.

Now recurve the storm as the models do, it still leaves about 1-2 degrees lat which when extrapolated 5 days out is a very large error. I dont buy some of the models since they had Bill moving west northwest (where it is suppose to be). I'm still not a 100 percent sure on this, so it remains a watch and see but so far Bill has not turn north.
Thank you 456, as usual you place things in a clear perspective and understandable language...appreciate it. I dislike having to ask so many questions, but is there a particular time frame in which we should know better as to the possible path. Had to change my portrait picture, so you may not recognize my sign. (Thanks for not correcting my English)
Member Since: Ιούλιος 17, 2009 Posts: 71 Comments: 26131
I guess the "F5" madness will be starting in about in hour.
those metal roofs are nice if you live in the midwest
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Quoting sngalla:


Lol! Just got hurricane impact windows this past Wednesday. Rated up to 150 mph.
and they work take it from me mine were tested and came through with flying colors two years ago
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i pray harder !! lol !
Member Since: Αύγουστος 4, 2008 Posts: 0 Comments: 12
2430. jipmg
yikes ana not looking good, the shear is having its effects, Bill on the other hand...
Tampa, Velocity Azimuth Display Wind Profile Range 124 NMI

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2428. flsky
Quoting RENONV:
StormW

I hope you are still on to answer my question. Are you a professional in predicting weather? If your answer is yes, then the blogers on this site should look up the definition of a professional. That should qualify your credentials and your expert analysis. For those who are not professionals by definition are only rendering an opinion and they should qualify their assumptions/predictions as a non-professional analysis. There is a handful of blogers on this site of which I completely value their ability to analyze these storms and make informed analyses that I believe do not carrier the title of a professional meteorologist. There are even a few bloger’s that I believe have a love and god given talent to analysis these system and make educated predictions that I scroll by when seeing their names because of their arrogant attitudes. I feel that’s unfortunate for them in my opinion as their attitude decays their ability to gain the respect from others. There are on lookers here that desire to know what the future may hold for thier safety. These individuals have natural talent and ability to hopefully protect someone who needs to heed their foresight is placed on ignore because of thier arrogances

Back to my hole.


You learn who to read and who not to read very quickly during hurricane season.
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Is 91L any threat to us in Louisiana? I live along the south-central coast of Louisiana.

It's about right for a TC to interrupt school as soon as it starts for us, though.
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Quoting Thundercloud01221991:
I think we have a TS in the Gulf by 11 PM

If so, I would have enough time to become a hurricane
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no shutters here..have original thick glass and 1929 iron bars with flamingos on them over every window !! not a scratch on any window even when the roof left during jeanne !
Member Since: Αύγουστος 4, 2008 Posts: 0 Comments: 12
2424. amd
Bill will get very close to buoy 41026 later tonight. Unfortunately, there are no pressure measurements with this buoy. But, we will know the types of winds that Bill possesses.

Here is the link:

Link
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Quoting stormbottom:
ps...got a 150 mph rated metal roof..bring it on bill !


What happens when the winds are 160
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2422. eye
IMO you arent a meteorologist unless you got the schooling, there is a reason people go to school for it. It is a big difference getting a certificate vs 4 years or more of college. You can say this that or the other about the definition, but that is splitting hairs.
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Pat - you still on?
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Quoting jpsb:
Does it have a surface low yet? If it does, then anything can happen. Just depends on how long it stays in the warm gulf waters.


no clue...
Member Since: Ιούλιος 2, 2009 Posts: 0 Comments: 2811
I witnessed a few of those 150mph metal roofs looking like a spent sardine can
Member Since: Ιούλιος 10, 2005 Posts: 3 Comments: 1279
as i posted this morning i firmly believe boyh stormswill be a caribben event affecting NWcaribbean and eventually the GOM, and ibase my projection on current patterns just look at the entire atl basin and its plain to see, i am begining to get worried, not for ana but bill.
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2417. sngalla
Quoting stormbottom:
ps...got a 150 mph rated metal roof..bring it on bill !


Lol! Just got hurricane impact windows this past Wednesday. Rated up to 150 mph.
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Quoting cajunkid:


happens this time ever year on here


Like the picture....funny
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2415. PBG00
Quoting Vortex1094:
Why would you wishcast a major hurricane at yourself?


I was answering the high school question..highschool in Palm Beach County starts August 18th
Member Since: Οκτώβριος 20, 2005 Posts: 14 Comments: 6650
Quoting Skyepony:
Severe Thunderstorm Warning up in N Brevard..weak rotation..


just starting to get my first bit of rain right now. (south of the TiCo Apt) very lilght though
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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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