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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It is starting to get breezy in panama city beach
Member Since: September 19, 2005 Posts: 0 Comments: 24
1624. 996tt
Hey Ike. Where are you located? I was thinking about heading to a spot near Grayton and seem if swell was any better, but decided to stay put. A friend told me it was poor form chop an hour ago.
Member Since: Posts: Comments:
Quoting stormwatcherCI:
If Bill is moving forward at a faster speed does that mean more chance it enters the Caribbean ?


I doubt Bill will enter the Caribbean. since its already moving wnw.

It is the concern of Bill being closer to the NE Leeward Islands than what is being forecast.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Funkadelic:
I just dont see how bill could affect The state of florida. Maybe im missing something, but even the models are clustered nicely and have been for 2 days.


Funk it is possible that it could bust the trough, whether at that point it moves on to FL is another story. It is not even at that point yet so it getting to be a tiresome subject on the blog.
Member Since: July 7, 2005 Posts: 0 Comments: 5414
Quoting FloridaTigers:


No, he's not. 16 MPH at most.
yes he is, calculating how much space he has covered from the 11 o'clock advisory to know, he has gone at 22.5MPH
Quoting Weather456:


hard to say. The current forecast is well away from the islands, so a shift would place it a distance still. but I still dont buy the NHC official track. More than often, these systems never end up at there 5 day position, ie. Dean and Ike


Ok lets clear up this thing.... Weather456: How fast is bill moving right now?
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Quoting SouthALWX:
Center looks nearly stalled to me =/ Maybe a northwest component

Center is elongated. The point of the elongation takes it straight to Pensacola. Looking like it might try to wind down the coast.
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You right Kman that northern movement could start insuing itself
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Quoting WeatherMSK:
Bill is headed towards the Carolina's. Not saying it will hit but it will be close.


That is my thinking. Maybe it'll skirt the outer banks.
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Quoting stormwatcherCI:
If Bill is moving forward at a faster speed does that mean more chance it enters the Caribbean ?


It doesn't seem like Bill will go into the Caribbean if it intensifies. Hurricanes (stronger ones) tend to move poleward.
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1615. Skyepony (Mod)
Claudette on MIMIC

Interesting presentation..

I'm really amazed how fast this loaded on LINUX VS my Windows beast.
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Bill becoming more compact and it has an eastern eye wall:



1613. Relix
Bill will not feel the through at all. The steering is too strong quite probably, should also limit development a tad bit. This is bad for the big islands and then the east coast. Oops.
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Bill is N of the next forecast point. Don't know if this is a short term trend or not
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Quoting canesrule1:
it is actully moving at 22.5MPH


No, he's not. 16 MPH at most.
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Definite WNW movement on the radar, exposed center so i dont see any strengthening in the short term but if it stays over water overnight it might.

Member Since: July 29, 2006 Posts: 28 Comments: 1800
Quoting Weather456:


a faster bill feels the weakness at later intervals. It means more west than maybe originally forecast. we have to see if Bill continues to do so over the next couple of days
If Bill is moving forward at a faster speed does that mean more chance it enters the Caribbean ?
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Quoting mks:


weather 456; if bill speeds up how much closer do you suspect it might pass to the northern leewards?


hard to say. The current forecast is well away from the islands, so a shift would place it a distance still. but I still dont buy the NHC official track. More than often, these systems never end up at there 5 day position, ie. Dean and Ike
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Funkadelic:

There is no way in hell he is moving that fast! He is moving 13-16mph at most.

Yeah, NHC has Bill moving WNW at 16 mph.
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1606. Skylink
I have just updated the web cams, click below for cams in the path of Claudette. If you have any extra links I will add them, so let me know thanks!


Link
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Center looks nearly stalled to me =/ Maybe a northwest component
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Quoting IpswichWeatherCenter:


Oh - so basically 2003 Bill = 2009 Claudette, and 2009 Bill = 2003 Claudette (Cat 1 Hurricane, hit Texas)


Kind of, but Bill03 hit from the west (on LA) while Claudette09 is hitting the FL Panhandle from the east. And Bill09 is still indeterminate on whether it recurves or not.
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a lot of experts on here today i see
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What!? Bill at 22.5 mph??? That would not be good.
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1601. IKE
Quoting Patrap:
Ike,trouble in that Band a coming,squally,..with some good Gusts.








Just went down to my dock and saw those low clouds and rain moving in.....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1600. GatorWX
Quoting Michfan:


LOL. Shes nowhere near organized enough as of right now form an eye. The center is a little exposed atm.


completely exposed over western quads.
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I just dont see how bill could affect The state of florida. Maybe im missing something, but even the models are clustered nicely and have been for 2 days.
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Patrap, Looks to me Claudette is heading toward Pensacola by the COC? I'm not taking into affect the look that the storms are moving, just the COC. Is that correct?
Quoting Funkadelic:

There is no way in hell he is moving that fast! He is moving 13-16mph at most.
it is actully moving at 22.5MPH
Those of you on the right side is going to get some pretty gusty winds. 50 knots + forward speed



Meanwhile, Bill's eastern eyewall

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Funkadelic:

There is no way in hell he is moving that fast! He is moving 13-16mph at most.


Sorry, I just went by satellite loops at start and end positions and used the time elapsed. We will see.
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1594. jipmg
Quoting IpswichWeatherCenter:


I agree with Funkadelic.


you should look at the satellite then
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Bill is headed towards the Carolina's. Not saying it will hit but it will be close.
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1592. jipmg
Quoting Funkadelic:

There is no way in hell he is moving that fast! He is moving 13-16mph at most.


well we aren't in hell so yes its moving that fast based on satellite, its really speeding up.
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Quoting canesrule1:
wow, if it continues at that speed it will surely blow past the trough and effect SFLA.

let me guess, you live in south florida, lol
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If Bill speeds up like Ana did, then yes I could predict Bill being a S FL issue, otherwise I think it will recurve.
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http://magicseaweed.com/Destin-Surf-Report/851/
.

Not much to it yet.

Swell
2ft @ 5secs 153°
Wind
7mph
86° -
Temperature
Sea 86°f Air 84°f
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Quoting Funkadelic:

There is no way in hell he is moving that fast! He is moving 13-16mph at most.


I agree with Funkadelic.
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Quoting Weather456:


a faster bill feels the weakness at later intervals. It means more west than maybe originally forecast. we have to see if Bill continues to do so over the next couple of days



yup its a wait and see


and has am postinng this this is my commet # 35,000 commets that i have made here on WU
Member Since: May 21, 2006 Posts: 5091 Comments: 115352
1586. sngalla
Quoting FLHurricaneChaser:


There is no chance of that. Weakness is too big and that trough is going to pick it up.


never say "never"!
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1585. GatorWX
Quoting HurricaneJoe:
The COC of Claudette isn't nearly as well defined as it was a few hours ago


I agree, however it looked best, I think, at 5am this morning. I still swear there was a pseudo-eyewall trying to fire up on her east side. Not really an eyewall, but a semi circular band of intense thunderstorms around the tight little center. This was around the time they upgraded to td4. I so wish a plane was inside her at that time so we could have had accurate readings, not satellites. Satellite estimates are not nearly as accurate and often underestimate these very small storms. It was especially small at 5am.
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1584. mks
Quoting Weather456:


a faster bill feels the weakness at later intervals. It means more west than maybe originally forecast. we have to see if Bill continues to do so over the next couple of days


weather 456; if bill speeds up how much closer do you suspect it might pass to the northern leewards?
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Quoting canesrule1:
two more big tropical waves before bill..
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Quoting FLHurricaneChaser:


There is no chance of that. Weakness is too big and that trough is going to pick it up.

No chance? you sound worse than he does in being dead set on an idea
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Quoting BA:


yeah, and mine will never zoom out or pan for some reason
Are you using Safari for your browser? Try downloading Firefox or Opera for Mac.

Wunderground does have a support page. Someone here I'm sure has a link.
Member Since: September 1, 2007 Posts: 0 Comments: 1344
Quoting serialteg:


thats what im talking about!

which reminds me...

thank you! im heading out to see if i can find a better wetsuit. I'm getting bad rash from my board and it looks like its gonna be a busy surfing week for me :D
Have fun and be careful.
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Woohoo! Home from work...tracking 'er in..

Here's a link to Schooners in PCB (bout 5 minutes from me).....live webcam

Link
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Quoting canesrule1:
wow, if it continues at that speed it will surely blow past the trough and effect SFLA.


There is no chance of that. Weakness is too big and that trough is going to pick it up.
Quoting dcoaster:
Well from my calcs using lat/long to distance, Bill is somewhere in the 20-23mph speed range.

There is no way in hell he is moving that fast! He is moving 13-16mph at most.
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1576. Patrap
Ike,trouble in that Band a coming,squally,..with some good Gusts.






Member Since: July 3, 2005 Posts: 426 Comments: 129090
they did other 2 bid they for get to do bill??

Link
Member Since: May 21, 2006 Posts: 5091 Comments: 115352

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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.