Ana, Bill,--and Claudette?

By: Dr. Jeff Masters , 1:52 PM GMT on August 16, 2009

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After one of the slowest starts to hurricane season in the past twenty years, the hurricane season of 2009 has exploded with activity over the past 48 hours. This morning, Tropical Depression Four joined Ana and Bill in the Atlantic, and appears poised to become Tropical Storm Claudette later today. Indeed, this may already be Claudette, as morning's QuickSCAT pass showed top winds of 45 mph. NEXRAD radar animations out of Tallahassee, FL, show a small but well-organized tropical cyclone with plenty of heavy thunderstorm activity, and improving low-level spiral banding. Satellite loops show an area of intense thunderstorms with cold cloud tops expanding near the storm's center.


Figure 1. Current long-range radar out of Tallahassee, FL.

It's pretty amazing (and a little unnerving) how quickly this storm sprang up. TD 4 developed literally overnight, and has the potential to be a strong tropical storm by the time it makes landfall tonight along the Florida Peninsula. TD 4 reminds me of 2007's Hurricane Humberto, which became a hurricane just 24 hours after first appearing as a tropical depression. I don't think TD 4 has time to reach hurricane strength, since wind shear as diagnosed by the SHIPS model was moderate, 10 - 15 knots, but it does have time to strengthen into a 50 - 60 mph tropical storm before landfall. Given that the storm is so small, storm surge flooding should not exceed 3 -5 feet, and will not be the major hazard from TD 4; inland flooding from heavy rain of 3 - 6 inches is likely to be the main threat from the storm.

Tropical Storm Ana continues to struggle
Tropical Storm Ana continues to struggle. Dry air continues to plague the storm, thanks to the large area of Saharan air the storm is embedded in. Ana's heavy thunderstorms are limited to just one small spot near the center. Wind shear appears to have lessened some, though, since yesterday. Thunderstorms were not able to form at all near the center yesterday, since strong wind shear tends to blow a storm's heavy thunderstorms to one side of the storm, exposing the low-level center to view. With heavy thunderstorms building near the center this morning, shear appears to be less of a problem for the storm. Top winds seen by this morning's QuikSCAT pass were about 35 mph. The outer rain showers from Ana should appear on radar out of Martinique today.

Shear is low (5 - 10 knots), and is forecast to remain low for the next two days. SSTs are warm, 28°C, and will warm further over the next two days. However, there is so much dry air around Ana that significant strengthening appears unlikely. Nearly all of the models predict Ana will dissipate sometime in the next three days, though the HWRF and GFDL predict that this will happen because Ana will move over the rugged terrain of Hispaniola. Ana is likely not strong enough to survive an encounter with the big island that the Dominican Republic and Haiti share. At this time, it does not appear that Ana will be moist enough to cause a major flooding disaster on Hispaniola.


Figure 2. Water vapor image from this morning showing the large area of dry, Saharan air surrounding Ana, and lying to the northwest of Tropical Storm Bill. Image credit: NOAA/SSD

Tropical Storm Bill gathers strength
Tropical Storm Bill is gathering strength in the middle Atlantic Ocean, and appears poised to become a powerful Cape Verdes-type hurricane later this week. QuikSCAT data from this morning shows a large circulation with top winds of 35 - 40 mph. Water vapor imagery (Figure 2) shows that there is some dry air to the northwest of Bill, and this dry air is being drawn into Bill's center, slowing intensification. It will likely take another day before Bill can moisten the atmosphere enough to ward off the dry air, and allow more significant intensification.

Wind shear is low, 5 - 10 knots, and is forecast to be in the low to moderate range, 5 - 15 knots, for the next five days. Sea Surface Temperatures are about 27.5°C, and will remain in the 27.5 - 28°C range the next four days, then warm substantially as the storm nears the Lesser Antilles Islands. The combination of low wind shear and sufficiently warm SSTs should allow Bill to intensify steadily to hurricane strength by Wednesday.

The big news is that our most reliable computer model from last year--the ECMWF model--appears to have made the right call yesterday, forecasting that a major trough of low pressure would develop along the U.S. East Coast, turning Bill more to the north. All of the other models--with the notable exception of the UKMET model--have now jumped on the ECMWF bandwagon, forecasting that Bill will pass well north of the Lesser Antilles Islands. The UKMET has Bill hitting the islands, but is being discounted since it is an outlier. It currently appears that the trough approaching the U.S. East Coast will be strong enough to recurve Bill before it reaches the U.S., though it is too early to be confident of this. Several of the longer range models show Bill passing near Bermuda or Nova Scotia, Canada.

I'll have an update later today.

Jeff Masters

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825. IKE
Quoting KEEPEROFTHEGATE:
how ya doing friend got a few things for the ride i hope were are you ike are a close to Apalachcola fla thats impact zone for the c storm


I'm good to go.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Weather456:


nope, others persons have said the samething.


And yet you feed the fire. Just let it go for crying out loud.
Member Since: September 7, 2007 Posts: 0 Comments: 1747
12z models for tiny ana have shifted some.
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I see we have Claudette now...
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Member Since: July 3, 2005 Posts: 428 Comments: 129770
Quoting FLWeatherFreak91:
Can someone post the link to the Google Earth app for tracking the recon flights? Thanks


http://www.guiweather.com/kml.html

Left-hand column, middle of the page.
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Quoting Relix:


Not everything is trolling, its just a light joke and it made me laugh. That's not trolling at all. Just light fun that we all NEED to have. Don't look at everything with a negative light Drak!!

Ana still moving WNW it seems, northern of her forecast points. Bill also north of them but I just can't see when it will do the NW turn.


I am not JFV and I don't appreciate people saying that I am him.
Member Since: October 28, 2006 Posts: 57 Comments: 30813
Quoting Dan187:
55kt flight level winds


Say what? I'm watching the flags in real time and there is nothing anywhere near that so far. For either storm. Ana flight is seeing 10 knots, Claudette flight is seeing around 25 knots heading for COC.
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In addition to the 55kt flight level winds (925mb), SFMR estimated 59kt surface winds, pressure was extrap 1008
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Quoting rareaire:

name


kind of made conch's point! just wrong handle


Lets hope he doesnt make any sudden stops
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Can someone post the link to the Google Earth app for tracking the recon flights? Thanks
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813. Relix
Quoting Drakoen:


You are a featured blogger lol? Just as much as a troll


Not everything is trolling, its just a light joke and it made me laugh. That's not trolling at all. Just light fun that we all NEED to have. Don't look at everything with a negative light Drak!!

Ana still moving WNW it seems, northern of her forecast points. Bill also north of them but I just can't see when it will do the NW turn.
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Quoting Drakoen:


You are a featured blogger lol? Just as much as a troll


you are now on my ignore list buh-bye kid
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811. JRRP
sorry... i saw the convection that is expanding
i am out
Member Since: August 16, 2007 Posts: 0 Comments: 6213
Quoting FLWeatherFreak91:
Page with information about Z-R relationship

http://www.srh.noaa.gov/tae/research-zrpaper.php


Thanks again
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Quoting BenBIogger:


Hey Drak

0Z ECMWF shows a weak low passing between Cuba and Florida.
ECMWF
probably the wave east of bill, prob danny.
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@799, really impossible to say. That far out any prediction can easily be wrong by 1,000 miles...I think the odds of a pre-US curve are good but it's certainly not out of the question it could hit NY.
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Quoting drg0dOwnCountry:
Seems Claudette is driven extremly by the GOM SST's.


GOM ssts are actually quite low in that area compared to the western side.
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Quoting tc1120:
Long time reader, first time poster. I know you guys will be able to help shed some more light on the chances of Bill striking Long Island or North? I see it is being pushed out to see but some models I've seen keep it on more of a WNW track right at the east coast. I've been keeping on eye on this storm closely because I saw a model early when Bill just moved off the coast that showed it gaining a ton of strength and sweeping through the OBX back over open ocean and slamming into NY at cat1+. but Of course that fell apart fast. My real reason for asking this question is because I'm a surfer and I tend to stick around to the last minute getting any swell I can, but tourism has been crazy here this summer and If a storm is going to be coming my way I want to be fully prepared to leave before I can't get off my island (traffic jams).

I know it's still hard to tell because the path is changing every day, but any information would be helpful.


theres a chance, if u had bucks i would recommend a trip to puerto rico...

then after catching bill's north swell here, you head to obx and rip the east coast...

would be quite cool
Member Since: August 22, 2006 Posts: 2 Comments: 1988
Page with information about Z-R relationship

http://www.srh.noaa.gov/tae/research-zrpaper.php
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Quoting Weather456:


nope, others persons have said the samething.


No way... Drak has much better writing/grammer skills..
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Judging by increasing reflectivity in the radar returns from near the center, I think we may have a strong TS/minimal hurricane at the final landfall ... meaning Judging by steering I think we may clip the part of the panhandle not impending intensification making a final land fall near or just west the destin fort walton area
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name
Quoting canesrule1:
troll



kind of made conch's point! just wrong handle
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Quoting Dan187:
55kt flight level winds


what recon mission are you watching? is it on google earth? i dont see that number anywhere
Member Since: August 22, 2006 Posts: 2 Comments: 1988
Long time reader, first time poster. I know you guys will be able to help shed some more light on the chances of Bill striking Long Island or North? I see it is being pushed out to see but some models I've seen keep it on more of a WNW track right at the east coast. I've been keeping on eye on this storm closely because I saw a model early when Bill just moved off the coast that showed it gaining a ton of strength and sweeping through the OBX back over open ocean and slamming into NY at cat1 . but Of course that fell apart fast. My real reason for asking this question is because I'm a surfer and I tend to stick around to the last minute getting any swell I can, but tourism has been crazy here this summer and If a storm is going to be coming my way I want to be fully prepared to leave before I can't get off my island (traffic jams).


I just started really looking at the models so I still don't have a full understanding. Hopefully I'm missing something.

I know it's still hard to tell because the path is changing every day, but any information would be helpful.
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Quoting FLWeatherFreak91:
reflectivity versus rainfall ;)


Thanks
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Quoting Drakoen:
Claudette has slowed down and has the potential to become a strong tropical storm.


Hey Drak

0Z ECMWF shows a weak low passing between Cuba and Florida.
ECMWF
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Quoting Weather456:


nope, others persons have said the samething.
oh, lol
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Quoting TampaHelpDesk:


What is the Z-R relationship?
I believe that it is the z axis to rain rate calculation.
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794. s1ecr
Why did NHC waited so long to finally say it is TS Claudette... In this post at 7:00 am posts were already talking about TS and probably Hurracane Cat1...Some post even suggested to up the warnings to Hurricane for peoples safety... This does not make sense why NHC did not do this. Few of the post even referred to Humberto... Instead of waiting until now 5 hours later.
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Quoting TampaHelpDesk:


What is the Z-R relationship?
reflectivity versus rainfall ;)
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recon just arriving to ana...
Member Since: August 22, 2006 Posts: 2 Comments: 1988
The problem with the Drak=WS theory is that I'm pretty sure Drak lives in West Palm and WS lives in Ft. Lauderdale.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
55kt flight level winds
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Any chance of Claudette deciding she needs to stop in the Biloxi/Gulfport/Ocean Springs area for TatoNuts or something?
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Quoting Patrap:



..Stay Tuned,today into this evening should be a wild ride Wnw with the TS.

Folks inland along the Warned areas should brace for conditions to go downhill.

Make sure your ready with a Light source in case you Lose Power,and a NOAA radio for Severe Weather Warnings such as Tornadoes...
As soon as warnings go up I go to Firehouse. No need for radio. We get up-to-second recon through EMA, and other officials. But thanks for the warning. Wish I could hide in the house. Will me on here as much as possible with updates from the area though as I'm sure mobilegirl will also
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Quoting Skyepony:
Just wolk up...lol. Did I not call this since Hispanola? I see recon is in it now headed toward center. Yay. I know it's no major but glad this is finally being taken seriously.


thats what i was telling ppl that said this came from nowhere ... sigh
Member Since: August 22, 2006 Posts: 2 Comments: 1988
Claudette is still moving in, not stopped, people are just impatient. Unless the HH finds different I would expect 40 mph in the next advisory, since that's what their special statement had.
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Quoting IKE:


I'm here.
how ya doing friend got a few things for the ride i hope were are you ike are a close to Apalachcola fla thats impact zone for the c storm
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How hard is it to type Claudette? I think it's hilarious that everyone's calling it the C storm. LOL.
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Quoting ConchHondros:


Drak would have to log off...


Why are you trying to start something? Your post is probably being flagged by numerous people for trying to argue.
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Quoting ConchHondros:


Drak would have to log off...
troll
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778. Skyepony (Mod)
Just wolk up...lol. Did I not call this since Hispanola? I see recon is in it now headed toward center. Yay. I know it's no major but glad this is finally being taken seriously.
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Quoting ConchHondros:


Drak would have to log off...


sha-zing! lol lol lol You just hit the nail right on the head.
Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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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