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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Quoting IKE:


I see that center....appears south of Tyndall AFB......

Ike, you are about to get hammerd.
Get the generator gased up.
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Quoting jdjnola:


How many times is she RIP now? Wednesday, Thursday, Friday, Sunday...


gotta love crow

Member Since: August 22, 2006 Posts: 2 Comments: 1988
Quoting drj27:
well i guess im going to get off this cpu nothing to really going on in okaloosa county



yet...
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1422. Michfan
Looking at water vapor imagery there is a possibility that she may slow down but i don't think she is going to stall.
Member Since: September 7, 2007 Posts: 0 Comments: 1747
1421. Drakoen
Quoting MississippiWx:


No center relocation is occurring. Only one dominant center is evident on visible and radar imagery.


I agree. I need to see a vortex confirming center relocation
Member Since: October 28, 2006 Posts: 57 Comments: 30724
Destin, Florida

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Is it possible for Claudette to stall?
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It is far from a sure thing that Bill recurves
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Bill seems to be at 13N and 39W right now. That would put it .9N°, and .6°W of the 11 am advisory. You can clearly see it
here . Also, it appears to be North of it's next forecast point.
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SerialTeg: I'm in the Rio Piedras area.



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Pat-
I see what you are all looking at with Claudette - (COC relocation) but wouldn't recon be picking that up?
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Quoting CycloneOz:
CoC relocation more south and west in conjunction with slower forward speed...

I cannot even imagine how bad that would be...



No center relocation is occurring. Only one dominant center is evident on visible and radar imagery.
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1413. Michfan
Quoting CycloneOz:
CoC relocation more south and west in conjunction with slower forward speed...

I cannot even imagine how bad that would be...



Would give her alot more time over the open water which would result in alot more strengthening. Need her to hit land.
Member Since: September 7, 2007 Posts: 0 Comments: 1747
1412. drj27
well i guess im going to get off this cpu nothing really going on in okaloosa county
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Quoting WPBHurricane05:


And Ike. Was a cat 4 and headed SW. No one believed it until they saw it.

Depends how everything sets up.


So very true.... I really thought that Ike had S.E. Florida written all over it.... But shocked me when it turned like that.

Andrew fooled many folks.... Even folks at NHC went to bed thinking it was going up north like Bill only to find the next day the high built back in stronger and we all know too well what happened.....
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Claudette was moving 15mph at 11am advisory and now 13mph at 2pm. looks like the starting of slowdown? Not good!
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1409. IKE
Quoting Patrap:


Definately a Newer CoC forming,and better structure overall,but Claudette is right loaded still, rainwise, but expanding


I see that center....appears south of Tyndall AFB......
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1408. jpsb
Quoting tennisgirl08:


That's what I have been trying to say. She will have more time in the gulf waters - and I wouldn't rule out a weak Cat 1 at landfall if this is the case. Not sure if this will change the track any??
If that center moved 80 miles south and if Cluadette stalls we will be lucky if she is only a cat 1.
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1407. bcn
Quoting PcolaDan:

That is an upper level low, nothing tropical.


Thanks.
Quoting PcolaDan:

That is an upper level low, nothing tropical.


Thanks
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CoC relocation more south and west in conjunction with slower forward speed...

I cannot even imagine how bad that would be...

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Triniweatherboy if it spends more/majority of it's time out over the open waters of the Atlantic I count it as a fish storm and yes it May hit Bermuda but going up towards Bermuda is the open waters where mainly trade/charters boat travel so to me that would make it a fish storm if Bill hits/brushes Bermuda and everything isn't about the U.S. just the majority of the time it is.
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Quoting KEEPEROFTHEGATE:
bill becomes a hurricane after sunset today 456
I agree. Looking extremely organized now.
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Someone posted something from Miami's weather site that is slowing the blog down big time.
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1402. bigdil
looks like Claudette is really growing in the last couple sat pics on NHC..
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Quoting CycloneOz:
Worst case scenario for Claudette at this moment?:

She stalls.


That could set up a very bad scenario. Cat. 1/2 maybe if it stalled?
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Claudette center per the ADT:
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Quoting CycloneOz:
Worst case scenario for Claudette at this moment?:

She stalls.


It depends - it might be the Best Case scenario - as long as she doesn't expand her wind field. She can cool the waters down and die.
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Quoting bcn:
Sorry for the duplicated post, but I'm interested on opinions about loop at 25N-70W. Any one?

That is an upper level low, nothing tropical.
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1397. Patrap


Definately a Newer CoC forming,and better structure overall,but Claudette is right loaded still, rainwise, but expanding
Member Since: July 3, 2005 Posts: 427 Comments: 129435
It might just be happening with coc relocation.
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Worst case scenario for Claudette at this moment?:

She stalls.
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Possible center relocation of Claudette would be very interesting to say the least.
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Quoting FLGatorCaneNut:


And then there was Andrew.....


And Ike. Was a cat 4 and headed SW. No one believed it until they saw it.

Depends how everything sets up.
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1392. Drakoen
Tropical storm force winds are nearing the coast.
Member Since: October 28, 2006 Posts: 57 Comments: 30724
Tropical storm warnings could extend to gulfport if system slows.
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1390. bcn
Can 25N-70W join Claudette?
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Claudette is not hour to hour now...

She's minute to minute.
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COASTAL WALTON, BAY, GULF, FRANKLIN AS TROPICAL STORM CLAUDETTE APPROACHES...SUSTAINED TROPICAL STORM FORCE WINDS UP TO 50 TO 60 MPH ARE EXPECTED TO BEGIN EARLY THIS
AFTERNOON. TROPICAL STORM FORCE WINDS ARE PREDICTED TO SUBSIDE BY
EARLY MONDAY MORNING.

--------------------------------------------------------------------------------
JEFFERSON, WAKULLA SUSTAINED WINDS OF 30 TO 40 MPH WITH GUSTS UP TO 45 MPH WILL BE
POSSIBLE...MAINLY ALONG THE COAST IN ASSOCIATION WITH THE
APPROACH OF TROPICAL STORM CLAUDETTE. WINDS OF THIS INTENSITY MAY
CAUSE LIGHT WEIGHT LOOSE OBJECTS TO BE BLOWN AROUND BY THE STORM.
AS A RESULT...MAKE PREPARATIONS TO SECURE THESE ITEMS BEFORE THE
STORM APPROACHES.

--------------------------------------------------------------------------------
TAYLOR, DIXIE THE LATEST AREA FORECAST IS FOR MAXIMUM WINDS OF 15 TO 25 MPH
WITH GUSTS TO 30 MPH. HOWEVER...AS TROPICAL STORM CLAUDETTE
APPROACHES...STRONGER WINDS ARE STILL POSSIBLE. CONTINUE TO
CLOSELY MONITOR THE FORECAST FOR ANY SIGNIFICANT CHANGES AND BE
READY TO ACT.

--------------------------------------------------------------------------------
INLAND WALTON, HOLMES, WASHINGTON, JACKSON, CALHOUN, LIBERTY TROPICAL STORM CLAUDETTE IS EXPECTED TO CONTINUE MOVING TOWARD THE
FLORIDA PANHANDLE COAST WITH THE POTENTIAL FOR SUSTAINED TROPICAL
STORM FORCE WINDS UP TO 50 MPH ACROSS INLAND AREAS OF THE FLORIDA
PANHANDLE. SUSTAINED TROPICAL STORM FORCE WINDS ARE EXPECTED TO
BEGIN THIS EVENING. TROPICAL STORM FORCE WINDS ARE PREDICTED TO
SUBSIDE BY EARLY MONDAY MORNING.
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Quoting jpsb:
Cluadette is becomming very impressive, a center relocation a significant distance south/west would be a real game changer. This is something to pay serious attention too.


That's what I have been trying to say. She will have more time in the gulf waters - and I wouldn't rule out a weak Cat 1 at landfall if this is the case. Not sure if this will change the track any??
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Quoting CycloneOz:
Claudette is far from finished.

This is why the GoM is such a bad place for TCs to develop right now.

She may be shifting a bit south, and still has plenty of time to develop.

DMIN and DMAX will not effect this system. GoM temps are more than high enough to continue development into the evening.

We better hope she moves ashore fast now. Otherwise, a slower more westward track could spell a bit of a disaster for my home town.
I think it will become a hurricane before landfall
Quoting Sfloridacat5:
Based on Dr. Lyon's comments (which I'm not sure I trust after last night), a stronger Bill will favor a more northerly turn and keep him off the East Coast.


And then there was Andrew.....
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Well, at least I won't have to water my wife's plants while she's out of town - (G)

And to all who see a relocating of Claudette's center - personally haven't seen it myself.
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Quoting Patrap:


Looks to be stalled, Pat.
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1382. KEEPEROFTHEGATE (Mod)
Quoting Weather456:
Both Bill and Claudette is stregthening

Bill is forming an eyewall





bill becomes a hurricane after sunset today 456
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Hi all. Back from golf LOL

I just saw this from the 2 pm advisory

" Data from an Air Force hurricane hunter aircraft
indicate that Ana is poorly organized and could dissipate as a
tropical cyclone later today."

IMO Ana was no longer a tropical cyclone from this morning. Quikscat did not show a closed low but in any event my call for dissipation into an open wave today seems to be more than likely.
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Claudette is far from finished.

This is why the GoM is such a bad place for TCs to develop right now.

She may be shifting a bit south, and still has plenty of time to develop.

DMIN and DMAX will not effect this system. GoM temps are more than high enough to continue development into the evening.

We better hope she moves ashore fast now. Otherwise, a slower more westward track could spell a bit of a disaster for my home town.
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1378. CJ5
The blow up of convection in the gulf over the past three hours is amazing!
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1377. IKE
Tyndall AFB C Tower....

Wind Direction (WDIR): SE ( 130 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 39 kts
5-day plot - Wind Gust Wind Gust (GST): 43 kts
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.95 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.06 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 75.6 °F
5-day plot - Water Temperature Water Temperature (WTMP): 84.9 °F
5-day plot - Dew Point Dew Point (DEWP): 74.7 °F
5-day plot - Wind Speed, Wind Gust and Atmospheric Pressure Combined plot of Wind Speed, Gust, and Air Pressure
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting reedzone:
WOW!! Bastardi proves my very point! Carolinas to New England needs to watch Bill, PLEASE don't let your guard down just because models show a recurvature and people who are boldly saying it won't hit.. We don't know yet, give it time.


I said that earlier on and posted the link for bastardi which evry1 ignored except u i think, but someone else posted the same link and then evry1 wathed it. Bill will not be a fish storm, the extent on his impact i am not too sure about as yet.
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Quoting HurricaneRoman:
haha, poor little ana, she just cant get it together! if she goes over the islands she for sure done for


After seeing how fast Claudette fired up overnight, I won't write off Ana if her remnants get to the GOM.
Quoting FLHurricaneChaser:


Give it up. Bill is out to sea. We gotta wait for the next wave train, not sure when it will be. Perhaps the end of this month.


There are 2-3 waves crossing Africa right now.
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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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