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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1962. Drakoen
Quoting zoomiami:
Why most meteorolgist have a degree, there are other ways to learn besides colleges. Storm is formally trained through Navy programs, and some others that are given through the Met schools.

Only the arrogance of youth would believe that the only way to become something is a degree. I know many people who have lots of pieces of paper, and can't fight their way out of a brown paper bag.


Arrogance of youth? LOL! Surely you jest.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Quoting BrandiQ:


Oh ok. So then we will see an update for him at 11PM? I'm curious to see if his cone changes...


the next update is 11PM but you can begin checking by 10:30
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Quoting BrandiQ:
How come Ana was updated but not Bill at 8PM?

Ana closer to land , and already tropical storms watches for the leeward Island?
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Quoting Drakoen:
Anaster and Billster!


Both looking impressive but bill looks like a Category 1
Quoting superweatherman:
that you think of the new models weather456 for ANA? Is it going to be a player or just die after passing Cuba


sometimes you have to throw out the models and make your own forecast based on experience and whats actually happening. I expect Ana to continue towards the west northwest, reaching the islands by Sunday/Monday, Puerto Rico Monday, the Dominican Reb, Monday/Tuesday and Cuba by Tuesday/Wednesday. What ever is left of Ana after the land interaction emerges over the GOM in 5-6 days. How much is left will determine the degree of concern Ana posses in the GOM. There is still a chance Ana slide north of the islands, in which it could become strong TS.
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Quoting scottsvb:



Bill has been forecasted by most models to move W or WSW over the past day....then by Sunday night or monday start more of a WNW path...nothing has changed...


I realize that, but something is going to have to change for him to make that bend.
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If the GFS' forecast setup is correct, then Bill will definitely go out to sea. Given to the ambiguity, it is still unknown, as some models such as the UKMET puts Bill south of PR...far south of PR. The overall troughing set up has been inconsistent with both the ECMWF and the GFS; both of them expected more ridging across the east coast yesterday.

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Quoting canesrule1:

I got a new image 'cause that one wasn't showing up :(
Member Since: August 9, 2009 Posts: 10 Comments: 4498
Why most meteorolgist have a degree, there are other ways to learn besides colleges. Storm is formally trained through Navy programs, and some others that are given through the Met schools.

Only the arrogance of youth would believe that the only way to become something is a degree. I know many people who have lots of pieces of paper, and can't fight their way out of a brown paper bag.
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Quoting BrandiQ:
How come Ana was updated but not Bill at 8PM?

Whenever there are watches or warnings issued for a particular system, then you still have full advisories every six hours, but you also have intermediate advisories in between them. Ana has TS watches up for it; Bill does not. Intermediate advisories are not yet necessary for Bill.
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New Twave added

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 18W S OF 16N MOVING W NEAR 15 KT.
ANALYSIS OF THE BAMAKO MALI UPPER-AIR TIME SECTION AND RECENT
5-DAY SATELLITE HOVMOLLER DIAGRAMS INDICATE THIS WAVE PASSED
BAMAKO NEAR 15/0000 UTC AND IS CURRENTLY PASSING DAKAR SENEGAL
AND EMERGING INTO THE FAR ERN TROPICAL ATLANTIC OCEAN WATERS.
LOW TO MIDDLE LEVEL CYCLONIC TURNING IS NOTED IN THE CLOUD MASS
IN CLOSE PROXIMITY TO THE WAVE AXIS WITH SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 7N-16N E OF 22W.
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1951. Drakoen
Anaster and Billster!


Member Since: October 28, 2006 Posts: 57 Comments: 29714
1950. Ldog74
Quoting IKE:


And the vorticity has increased this afternoon...


Hmm, the one good thing is that its time in the water should be relatively limited. Hopefully, we would be looking at a TS max
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Quoting MississippiWx:


What makes me stop and wonder about all the Northerly-biased models is the fact that Bill is still racing just South of due West at a fairly low latitude. For him to go north of the island chain, he's going to have to put on the brakes and/or strengthen significantly. Still could very much see a turn to the north eventually, but not before giving the islands a pretty hard punch.



Bill has been forecasted by most models to move W or WSW over the past day....then by Sunday night or monday start more of a WNW path...nothing has changed...
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Quoting MississippiWx:


What makes me stop and wonder about all the Northerly-biased models is the fact that Bill is still racing just South of due West at a fairly low latitude. For him to go north of the island chain, he's going to have to put on the brakes and/or strengthen significantly. Still could very much see a turn to the north eventually, but not before giving the islands a pretty hard punch.
yup
1946. BrandiQ
Quoting Weather456:


because Bill is further away from land. When system is not within a certain distance or time frame for affectying land, 6-hr advisories are issued. when do threathen land, 3-hr advisories are issued. I've seen 2hr advisory for the United States.


Oh ok. So then we will see an update for him at 11PM? I'm curious to see if his cone changes...
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Quoting Weather456:


because Bill is further away from land. When system is not within a certain distance or time frame for affectying land, 6-hr advisories are issued. when do threathen land, 3-hr advisories are issued. I've seen 2hr advisory for the United States.
they give intermediate when there is a watch or warning, i remember when Catrina 05' was about 5 hours away from making landfall in Miami they gave advisories every 30 minutes.
Quoting caneluver:


Bill will have to start heading north if he wants to follow that unrealistic track. not going to happen he is way south than the gfs ran


I agree, he is WAY South, is he not roughly where Ivan was,two days off the islands?

How much does the WRF develop the intensity before the islands?

I am thinking CAT 2?

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1942. jpsb
Quoting DestinJeff:
Quoting DestinJeff:
look near 26N, 83W ... i need to do some more research for surface reports, but man
Been watching that all day, so far no, or very weak surface low. Watching it tonight with interest.
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Quoting LAnovice:


Maybe technically no - but I would place my bets on an individual such as Storm with experience over a newly graduated BA "MET" (mostly inexperienced) any day of the year...it's frequently only AFTER kids graduate that they learn how to apply that "knowledge" that they gained in college.... In my opinion - college teaches you skills - but not always how to apply them...



True but Mets out of school know the latest and have the current skills. StormW and others that been tracking storms are quite knowledgeable..especially with experience and studying up on stuff yourself. When StormW mentions something.. I do also take what he says into account cause he dont tell more than what is nowcasting and nearcasting..and hardly ever goes more than a few days out...cause he knows patterns change and so do models.
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Quoting CycloneOz:
Westward...HO!

Oz, I bet you're packed and ready, huh?
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Quoting canesrule1:
Bill moving southerly, might mean more danger for SFLA:


What makes me stop and wonder about all the Northerly-biased models is the fact that Bill is still racing just South of due West at a fairly low latitude. For him to go north of the island chain, he's going to have to put on the brakes and/or strengthen significantly. Still could very much see a turn to the north eventually, but not before giving the islands a pretty hard punch.
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Quoting zoomiami:
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.


Thank you..
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that you think of the new models weather456 for ANA? Is it going to be a player or just die after passing Cuba
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Quoting Ameister12:
Wow!
Quoting MississippiWx:


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.


New Orleans?
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Westward...HO!
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Quoting BrandiQ:
How come Ana was updated but not Bill at 8PM?


because Bill is further away from land. When system is not within a certain distance or time frame for affectying land, 6-hr advisories are issued. when do threathen land, 3-hr advisories are issued. I've seen 2hr advisory for the United States.
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1931. JLPR
Quoting Weather456:
Edit

Hurricane by late Sunday



you think so? =S It is looking much better tonight than what it did today
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Wow!
Member Since: August 9, 2009 Posts: 10 Comments: 4498
1929. NOWCAST
Link
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1928. BrandiQ
How come Ana was updated but not Bill at 8PM?
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well if thats what it takes to be blocked, then thats fine, apparently observation isn't looked on too well here, what a shame
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Quoting jasoniscoolman10:
its look like the trough will not pick up bill anyhow. bill will be to far south and the trough by next weekend will be to weak to pick it up and to far from the north and the trough will slow down are go back to the north.
i agree
Holy guacamole, Bill is a monster.

He is too low for my liking, he will be coming through our islands.

Goodness grief!!!

RUN!
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Drakeon yesterday did say he believed S Florida looked right with Bill.... and I said and always say..dont look more than 3 days out. Of course Drakeon usually changes his mind and says he never said that! lol
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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.




Maybe technically no - but I would place my bets on an individual such as Storm with experience over a newly graduated BA "MET" (mostly inexperienced) any day of the year...it's frequently only AFTER kids graduate that they learn how to apply that "knowledge" that they gained in college.... In my opinion - college teaches you skills - but not always how to apply them...
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Quoting NOWCAST:
Check Tampa Radar!!!!
for what?
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Observation 8

UZNT13 KWBC 152328
XXAA 65231 99170 70482 04178 99014 26022 09520 00119 25017 09022
92801 20802 ///// 85531 17615 ///// 70179 10260 11545 50589 06156
08023 40761 15764 10016 30971 30925 ///// 25098 40747 12016 20246
53757 16016 15425 651// 35512 88999 77999
31313 09608 82308
61616 NOAA9 WX02A ANA OB 08
62626 SPL 1706N04831W 2323 MBL WND 09026 AEV 20801 DLM WND 11522
013145 WL150 09022 091 REL 1702N04821W 230853 SPG 1706N04831W 232
323 =
XXBB 65238 99170 70482 04178 00014 26022 11946 21407 22850 17615
33792 16850 44747 14056 55731 13262 66634 04058 77592 00433 88551
01362 99480 07746 11439 10960 22424 12941 33401 15764 44349 22764
55320 28356 66310 29323 77287 33132 88275 34956 99228 46332 11195
55158 22173 615// 33145 65744
21212 00014 09520 11989 09027 22955 09030 33817 11529 44655 11547
55609 10039 66575 11535 77536 08027 88521 09023 99482 08019 11460
10020 22416 09018 33323 13023 44251 12016 55205 16017 66184 15513
77170 20019 88166 18014 99158 17001 11156 34010 22154 34016 33153
33516
31313 09608 82308
61616 NOAA9 WX02A ANA OB 08
62626 SPL 1706N04831W 2323 MBL WND 09026 AEV 20801 DLM WND 11522
013145 WL150 09022 091 REL 1702N04821W 230853 SPG 1706N04831W 232
323 =

Observation 9:

UZNT13 KWBC 152339
XXAA 65231 99172 70474 04177 99014 26630 ///// 00123 25424 08521
92805 20621 09525 85535 18829 10524 70183 10460 11044 50589 06756
07520 40760 15963 09517 30971 30570 14524 25098 40750 14019 20246
53561 16516 15426 653// 15016 88999 77999
31313 09608 82315
61616 NOAA9 WX02A ANA OB 09
62626 SPL 1724N04749W 2329 LST WND 015 MBL WND 08023 AEV 20801 DL
M WND 11522 012145 WL150 08022 085 REL 1720N04739W 231518 SPG 172
4N04749W 232950 =
XXBB 65238 99172 70474 04177 00014 26630 11965 22602 22898 18809
33850 18829 44787 17264 55733 13667 66591 00536 77569 01156 88556
02541 99523 04962 11508 05956 22477 07962 33469 08556 44460 09158
55450 10363 66399 15963 77332 24974 88286 32764 99258 38750 11220
47957 22196 54562 33168 623// 44145 66140
21212 00014 ///// 11012 07023 22010 08023 33997 08521 44942 08527
55868 10518 66850 10524 77666 11045 88555 11534 99512 07523 11480
08015 22469 07016 33432 08514 44410 08018 55393 11017 66361 13020
77321 13523 88290 16027 99272 14531 11236 12515 22196 17516 33189
16013 44173 17512 55166 15014 66153 16017
31313 09608 82315
61616 NOAA9 WX02A ANA OB 09
62626 SPL 1724N04749W 2329 LST WND 015 MBL WND 08023 AEV 20801 DL
M WND 11522 012145 WL150 08022 085 REL 1720N04739W 231518 SPG 172
4N04749W 232950 =




1919. 10Speed
There sure is a lot of circulation over FL and out into the GOM at the moment.
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Quoting Weather456:
Edit

Hurricane by late Sunday

i agree 1000000%
Bill moving southerly, might mean more danger for SFLA:
Quoting CaneWarning:


I think Orca may have blocked you.


Your right.. I did...
Was StormW's assumption based on a "guess" or was in based on the available data at the time... my "guess" is it was based on the available data.. just like Jeff called for it to die.
Member Since: October 1, 2007 Posts: 81 Comments: 26493
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: October 28, 2006 Posts: 57 Comments: 29714

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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.