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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4564. Grothar
TO:StormwatcherCI

Thank you for your honesty. Quite an admirable trait. I am not an expert either, which is why I ask so many questions rather than contribute. One would not like to appear a fool amongst so many who DO know.
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Quoting reedzone:
Will you guys stop saying Bill is a fish storm. It's heading west when models have it heading NW already. Bill still has a decent chance to affect the Eastern Seaboard, it's still 2 weeks away from impacting anybody if any. Models will shift back and forth, soon, I bet the models will shift south again. Dean was forecast to be north of the islands at that same spot, and it went south of there track.

On the last Metsat loop it looks like it is starting to turn ot the NW. That is a sign that maybe the models are correct.
Member Since: May 20, 2009 Posts: 0 Comments: 1640
Quoting reedzone:
Will you guys stop saying Bill is a fish storm. It's heading west when models have it heading NW already. Bill still has a decent chance to affect the Eastern Seaboard, it's still 2 weeks away form impacting anybody if any.


Actually, if Bill doesn't turn north, he will affect the islands in 4-5 days.
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Quoting boomerang08:
what would possibly be worst for ana?

1)going through the 30 knt shear in the caribean

2)crossing cuba or hispanolia

enough with the polls already... they are getting a bit old and are a waste of space. my comment on ur poll is also a waste of space
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The Pensacola News Journal says nothing about Claudette this morning.

The NHC better hope that it doesn't spin up ala Humberto.

People will be screamin' "Why can't they predict a hurricane one day out!!!"
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4559. eddye
reedzone bill still can affect fl
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4541. theshepherd

Shep, my friend, gonna be a busy day here on the panhandle! Boats to secure, and preparations to make! I do believe that TS will be knocking on my door. Expect landfall between PCB and Destin tonight...
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Member Since: July 24, 2005 Posts: 407 Comments: 19076
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Do not count out Ana yet. Even if she does degenerate, she will head more westward, and into the very warm waters of the Caribbean, where she could strengthen at a good clip
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Quoting Weather456:
so in a weekend we had 3 named storms.

What have we learned?


You can never tell what Mother Nature has in store for us
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Will you guys stop saying Bill is a fish storm. It's heading west when models have it heading NW already. Bill still has a decent chance to affect the Eastern Seaboard, it's still 2 weeks away from impacting anybody if any. Models will shift back and forth, soon, I bet the models will shift south again. Dean was forecast to be north of the islands at that same spot, and it went south of there track.
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what would possibly be worst for ana?

1)going through the 30 knt shear in the caribean

2)crossing cuba or hispanolia
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Think with Ana, might be the fact they've already got burned on her once already.

What you don't wanna do, is say she's a TD on the verge of death, then she blows up again prior to hitting the islands and catching people unaware.

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Quoting WPBHurricane05:
TWC has one of the guys from the NHC on (Brennan)...he said there is no indication we have Claudette yet, but recon will go in.
\

He also said that they still think Ana is a minimal tropical storm. Hurricane hunters will fly into TD 4 as well as Ana later today.
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Says Ana appears to be a minimal TS.
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4548. cg2916
When I saw the NHC page I yelled out loud. TD Four? Dang, when it got active it got ACTIVE!
Member Since: December 21, 2007 Posts: 13 Comments: 3046
TWC has one of the guys from the NHC on (Brennan)...he said there is no indication we have Claudette yet, but recon will go in.
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Quoting TropicalNonsense:
there is a major south westward push by the bermuda high taking place right now.

this high is essentially the key player in bill and anna's track. the models are all currently way off with the intensity and oreintation and movement of this high. Bill and Anna may never see the trough 4-5 days out and may very well make landfall in south Florida if the high keeps digging in.


Florida Residents Stay Tuned to the Tropics .....





I don't see any southward push right now. bill is moving more towards the wnw.
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4545. Grothar
TropicalStormWatcher.

It would appear your observation may have some validity. It will be interesting to see if this effects the models later.
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Quoting Weather456:
so in a weekend we had 3 named storms.

What have we learned?
Anything can and will happen.
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once again, thanks for the links weather456.

i have a feeling that claudette (td4) is going to be a bit stronger than the NHC estimates. looking real good on radar right now and even the microwave imagery shows a possible eyewall forming , ala humberto.
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so in a weekend we had 3 named storms.

What have we learned?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
4514. HurricaneFCast 8:28 AM EDT on August 16, 2009
I just can't believe how quickly it is building and intensifying its thunderstorms


Yup. Welcome to the hot, shallow waters of the gomex.
The faster it moves, the better off our panhandle buds will be.

Foxxy my rose
Watch the high tide. Check yer ropes.
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Quoting Grothar:
TO: 456
Good Morning. I see you are up early. I just posed a question to stormwatcherCI, however, I would like your opinion if you don't mind. It appears on the NOAA runs that Ana is having a burst of convection slightly North of the 8:00 pm position. Could she be trying to form a new COC and how could this effect her forecast position.


It should not affect her forecast that much since she is wthin 48 hrs of the islands and there is only so much distance in the islands chain.

Also, Ana can produce sporadic burst of convection but until she can maintain and sustain it, i doubt she will amount to much.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Cotillion:


Oh, now you've done it.

You wrote her off once, she came back, you're writing her off again.. but most of all. You compared her to another female.

Now she'll survive, just to spite you!


I take it back, every word LOL
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Quoting kmanislander:


I haven't had time to look at that area closely but pressure at buoy 42057 just S of us is 1012 mb, not very low. I have to head out now for my golf game but will check in this afternoon.
Have a good day all
Thanks. Just know that tends to be a hot spot.
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CPC Prognostic Discussions
ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
19550727 - 19910825 - 19780813 - 19520825 - 19880811

Member Since: Posts: Comments:
000
WHXX01 KWBC 161236
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1236 UTC SUN AUG 16 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE ANA (AL022009) 20090816 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090816 1200 090817 0000 090817 1200 090818 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 14.6N 54.8W 15.9N 59.0W 17.6N 63.5W 19.5N 67.5W
BAMD 14.6N 54.8W 15.3N 58.0W 16.0N 61.6W 16.9N 65.3W
BAMM 14.6N 54.8W 15.3N 58.4W 16.0N 62.4W 17.0N 66.3W
LBAR 14.6N 54.8W 15.4N 58.3W 16.4N 62.1W 17.4N 65.9W
SHIP 35KTS 35KTS 39KTS 45KTS
DSHP 35KTS 35KTS 39KTS 45KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090818 1200 090819 1200 090820 1200 090821 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 21.2N 71.6W 24.3N 77.4W 26.4N 80.8W 27.5N 83.1W
BAMD 17.7N 69.0W 19.4N 75.5W 20.5N 80.5W 21.3N 84.7W
BAMM 17.8N 70.3W 19.4N 77.7W 20.7N 83.8W 22.0N 88.7W
LBAR 18.2N 69.8W 19.9N 76.3W 21.4N 80.3W 28.9N 79.1W
SHIP 51KTS 59KTS 70KTS 79KTS
DSHP 51KTS 47KTS 46KTS 55KTS

...INITIAL CONDITIONS...
LATCUR = 14.6N LONCUR = 54.8W DIRCUR = 275DEG SPDCUR = 18KT
LATM12 = 14.4N LONM12 = 50.7W DIRM12 = 272DEG SPDM12 = 18KT
LATM24 = 14.3N LONM24 = 47.6W
WNDCUR = 35KT RMAXWD = 30NM WNDM12 = 35KT
CENPRS = 1005MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 45NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

Still at 35kts, oddly.
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04L.CLAUDETTE
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting stormwatcherCI:
She is starting to fire convection again. I think she is a fighter. Anything going on in the SW Caribbean ? Lots of thunderstorms looks like.


I haven't had time to look at that area closely but pressure at buoy 42057 just S of us is 1012 mb, not very low. I have to head out now for my golf game but will check in this afternoon.
Have a good day all
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Quoting Grothar:
TO: 456
Good Morning. I see you are up early. I just posed a question to stormwatcherCI, however, I would like your opinion if you don't mind. It appears on the NOAA runs that Ana is having a burst of convection slightly North of the 8:00 pm position. Could she be trying to form a new COC and how could this effect her forecast position.
I wasn't ignoring you. Just don't know the answer so I left it for the experts.
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Quoting P451:


Thanks.

Last but not least - Africa WV



The wave train keeps coming.
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Quoting kmanislander:
Remember Dolly ?. TS force winds but no closed low and Dolly looked far more impressive than Ana.


Oh, now you've done it.

You wrote her off once, she came back, you're writing her off again.. but most of all. You compared her to another female.

Now she'll survive, just to spite you!
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Quoting caneluver:
Yep, Ana is history and Bill will be waving at the conus on his way by. TD 4 wont amount to much (Bad thunderstorm with som gusty winds).


and that makes it all well? What about the leewards and Bermuda, and not to mention the Bahamas.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
4528. Grothar
TO: 456
Good Morning. I see you are up early. I just posed a question to stormwatcherCI, however, I would like your opinion if you don't mind. It appears on the NOAA runs that Ana is having a burst of convection slightly North of the 8:00 pm position. Could she be trying to form a new COC and how could this effect her forecast position.
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TD# 4 is getting better organized, the only problem for it not to intensify fast is do to the approximate closeness to Florida. I think it will be between 45-60 mph at land fall, only a little stronger because the shear is low and the waters are real warm.
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On the Navy site - TD4 is Claudette
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Okay...where is the complaint department.

I have a depression that's spinning up into a TC and the ingredients for it to happen were all in place yesterday at this time...
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Quoting floridafisherman:
ty weather456. where can you find images like that? from the NOAA site?


you can find the shortwave imagery here:

you can microwave data here
Member Since: July 24, 2005 Posts: 407 Comments: 19076
000
WHXX01 KWBC 161232
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1232 UTC SUN AUG 16 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE FOUR (AL042009) 20090816 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090816 1200 090817 0000 090817 1200 090818 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 28.2N 84.2W 29.7N 85.9W 31.1N 87.6W 32.5N 88.9W
BAMD 28.2N 84.2W 29.3N 85.5W 30.2N 86.6W 30.9N 87.4W
BAMM 28.2N 84.2W 29.5N 85.7W 30.6N 87.2W 31.6N 88.3W
LBAR 28.2N 84.2W 29.8N 85.6W 31.5N 86.9W 33.4N 87.6W
SHIP 30KTS 35KTS 39KTS 45KTS
DSHP 30KTS 35KTS 29KTS 27KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090818 1200 090819 1200 090820 1200 090821 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 33.6N 90.1W 36.7N 90.1W 41.9N 84.0W 46.7N 78.2W
BAMD 31.5N 88.1W 33.4N 87.9W 36.6N 83.2W 40.8N 75.4W
BAMM 32.6N 89.2W 35.3N 88.6W 39.6N 81.8W 43.1N 71.8W
LBAR 35.5N 87.3W 38.7N 81.7W 38.2N 73.0W 35.4N 71.6W
SHIP 47KTS 46KTS 40KTS 37KTS
DSHP 27KTS 28KTS 30KTS 30KTS

...INITIAL CONDITIONS...
LATCUR = 28.2N LONCUR = 84.2W DIRCUR = 325DEG SPDCUR = 12KT
LATM12 = 26.3N LONM12 = 83.1W DIRM12 = 323DEG SPDM12 = 12KT
LATM24 = 24.2N LONM24 = 80.2W
WNDCUR = 30KT RMAXWD = 30NM WNDM12 = 25KT
CENPRS = 1011MB OUTPRS = 1015MB OUTRAD = 90NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN
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Remember Dolly ?. TS force winds but no closed low and Dolly looked far more impressive than Ana.
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Quoting Weather456:


I dont believe Ana is a tropical storm, just based on satellite imagery but the QS confirmed it.
She is starting to fire convection again. I think she is a fighter. Anything going on in the SW Caribbean ? Lots of thunderstorms looks like.
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4519. Relix
Quoting kmanislander:


Looks like an open wave to me


A cluster of thunderstorms to me haha.
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Quoting Weather456:


I dont believe Ana is a tropical storm, just based on satellite imagery but the QS confirmed it.


Looks like an open wave to me
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ty weather456. where can you find images like that? from the NOAA site?
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Quoting kmanislander:


What do you make of the quikscat pass of Ana ?


I dont believe Ana is a tropical storm, just based on satellite imagery but the QS confirmed it.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting floridafisherman:
anyone have any microwave or short wave imagery on TD4?




Member Since: July 24, 2005 Posts: 407 Comments: 19076
I just can't believe how quickly it is building and intensifying its thunderstorms.. The core is now building stronger rains to the west of its center, while the northern portion of the center is now also rain-wrapped, and there are at least 3 distinct bands to its south and east.
4-Hour Radar Loop
I'm going to try to catch a quick nap, lol, I'll be back! I don't know about many of you all, but I've just got a bad feeling this could intensify to be a bit stronger than residents of the Panhandle are expecting...
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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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