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 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.
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Quoting futuremet:
UM....

Image and video hosting by TinyPic


Future met - what storm is that? Ana or TD3? WOW!!
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guys I think TS ana will get the convection over the COC and get stronger same with TD3 which just needs the H. hunters to go in and find TS winds and the NHC also think a third storm will form
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Quoting atmoaggie:
90L consolidating verrrry slowwwwly


http://rammb.cira.colostate.edu/products/tc_realtime/storm.asp?storm_identifier=AL9020 09
90L outdated
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I understand typos.. I type very fast and never proof read so I make them all the time! LOL
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Quoting jurakantaino:
Why there is a difference with the symbols in the trops Fcst points, hurricane 1 and storm in the same map?


saludos de ponce!
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Quoting hunkerdown:
wait til the next model runs.


What time do they come out?
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Quoting stormpetrol:

No problem you could absolutely be correct, watch, wait and see, only time will tell.

Isn't it suppose to go wnw and reach latitude 18n 66w by Monday?
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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.
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Deadly Catastrophic 20mph winds racing through the Keys.
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Quoting hunkerdown:
wait til the next model runs.


What are you thinking? Thinking it will start to go more south or north?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting atmoaggie:
...chocolate mayor Nagin...

You know you are going to catch it from people who don't understand the context of this. :)

For those interested in the origin. http://www.wnd.com/index.php?pageId=34378

atmoaggie, you'll thank me later for this LOL
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748. IKE
ECMWF shows TD3 near 15N and 48W on Tuesday.

It's near 11.5N and 34W from the advisory. It's moving at near 17 mph. That would put it near the coordinates the ECMWF shows on Tuesday.

Looks like a threat to Bermuda if the ECMWF verifies.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting CJ5:
...FOLKS THE LATEST INFO OUT OF MY OFFICE INDICATES TO ME WE HAVE A CLOSED LOW AND ITS DEVELOPING QUICKLY..

There is nothing in the current observations that point to this being a fact, nothing.


people that stuff lies like that here should merit a serious IP ban

i know i make a lot of jokes but this is serious business here
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Quoting BrockBerlin:


Yes and the models indicate this is a decent possibility but obviously this far out the models are not entirely reliable.
wait til the next model runs.
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The suns affect on the satellite imagery make it appear to be more organized than it is. 03L is very unimpressive. Large. Lacks deep convection.
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Ana now exposed on west side. It's been through alot. I doubt this lastest problem will kill it.
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90L consolidating verrrry slowwwwly


http://rammb.cira.colostate.edu/products/tc_realtime/storm.asp?storm_identifier=AL902009
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Why there is a difference with the symbols in the trops Fcst points, hurricane 1 and storm in the same map?
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Quoting serialteg:


I'm sorry jade, I was just poking some fun at you! (hugs) You SHOULD be seriously considering and updating your "weapons cache" for hurricanes. I'm in Puerto Rico and I have been doing so too, as well as my family. We're hurricane-riders, us brethren...


No worries... I just find it so tough to find as much relevant info for this region sometimes. The bulk of them just repeat the NHC info. It's nice to have a place that has a dialogue discussing the tropics in addition to US content. Omar was not nice to us last year as parts of the island flooded out pretty badly - so my guard is up about these next two storms. Hope the tracking does shift north!
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Quoting P451:
1745Z - TD3
Looking pretty good to me.

VIS, RGB, WV, AVN, FUNKTOP, RAINBOW



dry air interfering on the n-ne quad imo
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Quoting Ameister12:
Poll Time!!!

What do you think Ana's going to do by next advisory.

A)Weaken
B)Stay the same strength
C)Strengthen

D) Polls have got to go away
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Andrew 1992 history
11 PM AST SUN AUG 16 1992 - declared a TD
location 11.2 N... 38.3 W
11 AM AST MON AUG 17 1992 - declared a TS
location 13.0 N... 43.3 W

Just for fun --the NHC's tracking map for Andrew:
hurricane,nhc,1992,hurricane andrew
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735. CJ5
...FOLKS THE LATEST INFO OUT OF MY OFFICE INDICATES TO ME WE HAVE A CLOSED LOW AND ITS DEVELOPING QUICKLY..

There is nothing in the current observations that point to this being a fact, nothing.
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Quoting atmoaggie:
Looks like we need to get the chocolate mayor Nagin on the phone and make sure he calls for immediate evacuation of NOLA for the pending rainy-wave.
Maybe stormno should give a call (I would love to be a fly on the wall for that conversation).


maybe a conversation transcript?
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Quoting rxse7en:
Dude, do you have to be warned every year about masquerading your posts as official weather statements? you could have deleted some here

Dude, do you have to quote the whole thing?
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Quoting stormpetrol:

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.
They don't exist.
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Quoting medic2luv:
Is it possible that TD3 will be a fish storm as far as the Cont US is concerned?


you'd have to ask a fish.
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We could be looking at Claudette late next week
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Quoting rxse7en:
Dude, do you have to be warned every year about masquerading your posts as official weather statements?


Do they trick you everytime?
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[Comment Deleted]
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??????
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Quoting JadeInAntigua:


ClearwaterSteve, Biloxi, Yonza - ty for the polite replies. Being that this storm is only a couple of days out from us I'm trying to sort out just how much preparation I should be doing today and tomorrow, especially with back to back hits as a possibility. I didn't mean to upset serialteg by asking a question though.. thought asking for additional information/opinions about the content of the blog was what the comments area was for lol.


I'm sorry jade, I was just poking some fun at you! (hugs) You SHOULD be seriously considering and updating your "weapons cache" for hurricanes. I'm in Puerto Rico and I have been doing so too, as well as my family. We're hurricane-riders, us brethren...
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Is it possible that TD3 will be a fish storm as far as the Cont US is concerned?
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One has to remember Ana is fighter & survivor, practically rose from the dead, you don't write off storms like that until there absolutely dead.
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Quoting yonzabam:


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.


ClearwaterSteve, Biloxi, Yonza - ty for the polite replies. Being that this storm is only a couple of days out from us I'm trying to sort out just how much preparation I should be doing today and tomorrow, especially with back to back hits as a possibility. I didn't mean to upset serialteg by asking a question though.. thought asking for additional information/opinions about the content of the blog was what the comments area was for lol.
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718. CJ5
Watching the RGB it appears that shear may have begun to relax and convection is ever so slowly reaching back to the center. It has a long way to go though...speaking of Ana.

On the FL blob, I do not see a single bouy pressure reading below 30 so it really needs to get some basic structure before it should even be considered.
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717. IKE
12Z ECMWF...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
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
Dude, do you have to be warned every year about masquerading your posts as official weather statements?
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ECMWF now forecast for another system to develop in the tropical Atlantic.
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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.