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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1125. KEEPEROFTHEGATE (Mod)
5:49 PM GMT on August 16, 2009
CLAUDETTE will make landfall at or slightly to the left of APALACHCOLA FLA with TROPICAL STORM FORCE WINDS with poss HURRICANE FORCE GUSTS IN NE QUAD
Member Since: July 15, 2006 Posts: 174 Comments: 54398
1124. SouthALWX
5:48 PM GMT on August 16, 2009
Quoting LightningCharmer:
Since there are some experts on here, and I posted this late in the last blog just before the new blog so it may have been missed so here goes again:

I've been following and studying weather as a hobby since childhood. Correct me if I'm wrong or blast me if you prefer. Regarding the somewhat higher pressure of Claudette, isn't it more important the relative pressure difference with the surrounding atmosphere than the actual pressure reading for the strength of a low, hence generally Pacific lows have lower pressure than Atlantic lows because the surrounding atmosphere has lower pressure overall.

True.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
1122. LightningCharmer
5:48 PM GMT on August 16, 2009
Since there are some experts on here, and I posted this late in the last blog just before the new blog so it may have been missed so here goes again:

I've been following and studying weather as a hobby since childhood. Correct me if I'm wrong or blast me if you prefer. Regarding the somewhat higher pressure of Claudette, isn't it more important the relative pressure difference with the surrounding atmosphere than the actual pressure reading for the strength of a low, hence generally Pacific lows have lower pressure than Atlantic lows because the surrounding atmosphere has lower pressure overall.
Member Since: September 1, 2007 Posts: 0 Comments: 1344
1121. canesrule1
5:48 PM GMT on August 16, 2009
-Recon moving straight into the COC if Claudette.

1120. Sfloridacat5
5:47 PM GMT on August 16, 2009
Looks to me like Claudette is moving more northerly and getting close to making landfall in the next few hours.
Member Since: September 16, 2007 Posts: 0 Comments: 7389
1119. Drakoen
5:47 PM GMT on August 16, 2009
Filtering out the dry air:
Member Since: October 28, 2006 Posts: 57 Comments: 30563
1118. catastropheadjuster
5:47 PM GMT on August 16, 2009
I was just wondering am I like on ignore where no one can see me? I asked a little further back on the blog if Mobile might get anything out of Claudette cause we have a boat repair shop on Chickasabogue Creek and we might need to get stuff off the floors so it won't get wet. I'm not wishcasting or anything just trying not to loose valuable materials.

Sheri
Member Since: August 24, 2006 Posts: 21 Comments: 3678
1117. hurristat
5:47 PM GMT on August 16, 2009
Quoting Drakoen:


1090. Looks like Bill is starting to wrap up a little more, got rid of that little line/hole thingy... wow that last phrase was really scientific.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
1116. Tazmanian
5:47 PM GMT on August 16, 2009
Quoting Stormchaser2007:
Very impressive.




wish storm???
Member Since: May 21, 2006 Posts: 5091 Comments: 115241
1115. Dakster
5:46 PM GMT on August 16, 2009
Quoting Grothar:
TO: Dakster

Who is Bill Kamal?


He was a met that was busted for arranging to have sex with kids.... He just got out of prison a month ago.
Member Since: March 10, 2006 Posts: 0 Comments: 10462
1114. stoormfury
5:46 PM GMT on August 16, 2009
reedzone i have been making that same obsrevation with IVAN and DEAN for a few days now. that is why i am going with the track of the UKMET thru the cental islands. the UKMET was on the button with both IVAN and DEAN
Member Since: August 22, 2006 Posts: 0 Comments: 2713
1113. Stormchaser2007
5:46 PM GMT on August 16, 2009
Very impressive.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
1112. Drakoen
5:46 PM GMT on August 16, 2009
Quoting pcolasky:


It appears to me Claudette is growing rather than moving. I just hope it stays East of P'cola


Maybe near Panama City Beach
Member Since: October 28, 2006 Posts: 57 Comments: 30563
1111. CapeFish
5:46 PM GMT on August 16, 2009
Quoting reedzone:
The models always do this.. They don't really focus on the high.. Ivan (2004) and Dean (2007) VERY good examples.. Ivan was supposed to hit South Florida, but the high kept going and it made it into the heart of the GOM and hit Alabama. Dean was supposed to go north of the Lesser Antilles, in fact Bill is in that very same spot where Dean was at the time it was foretasted to head north.. Instead the high remained strong and pushed Dean west. It's not official yet, lets wait and see what happen through the week.


I am not sure why for the last two days people here have compared how the models treated Dean is in anyway similar to Bill.

Look:
http://www.nhc.noaa.gov/archive/2007/graphics/al04/loop_5W.shtml

There was a very brief time, just an advisory or two that had Dean barely brushing by the northern islands, but they quickly righted themselves. Dean was not forecast to turn out to sea, which some people make it sound like.

Ivan's forecast was a bit more problematic, but it did stay in the five day forecast cone throughout. This is why you should focus on the entire cone, not just the middle.

Link:
http://www.nhc.noaa.gov/archive/2004/IVAN_graphics.shtml

Very different storms, and very different model histories.
1110. canesrule1
5:46 PM GMT on August 16, 2009
Quoting Drakoen:
WOW, convection is expanding.
Quoting WPBHurricane05:
Bill should have an eye tomorrow. Will be easier to see which way he is moving.
An eye at around 11 seems right.
1109. Babsjohnson
5:45 PM GMT on August 16, 2009
Quoting CaneWarning:



Yes, be careful, this could be like a strong afternoon t-storm, just longer!


This is more than a prolonged thunderstorm. Her track is very unknown at this time despite those forecasts.
Member Since: September 1, 2007 Posts: 3 Comments: 138
1108. tropicfreak
5:45 PM GMT on August 16, 2009
Quoting Drakoen:


Wow bill has really intensified.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
1107. CaneWarning
5:45 PM GMT on August 16, 2009
Everyone, do not worry, I just emailed WS to ge this analysis on Ana and Bill!
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1106. tennisgirl08
5:45 PM GMT on August 16, 2009
Bill is moving due west. When is he supposed to make that WNW/NW turn? better do it quickly.

Also, why are Ana and Bill moving so quickly??
Member Since: July 17, 2008 Posts: 0 Comments: 1242
1105. weatherfan92
5:45 PM GMT on August 16, 2009
Quoting Drakoen:


Looks like Bill has closed off the dry air.
1104. SouthALWX
5:45 PM GMT on August 16, 2009
Quoting Drakoen:
I see Claudette making landfall near Fort Walton Beach

That was my initial thought but check out thew symmetry. I don't recall the name of this effect but I know it exists, when cyclones are lopsided they tend to move slightly toward the centerline when other steering currents are weak. Given that C is slowing I think this could be the case. If she becomes symmetrical soon she could be over water a longer time as she stalls and begins a WNW motion.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
1103. Grothar
5:45 PM GMT on August 16, 2009
TO: Dakster

Who is Bill Kamal?
Member Since: July 17, 2009 Posts: 71 Comments: 26499
1102. HurricaneKyle
5:45 PM GMT on August 16, 2009
I just noticed this, but Bill looks similar to Dean as a 50-60 MPH storm.
Member Since: August 10, 2009 Posts: 3 Comments: 672
1101. CycloneOz
5:45 PM GMT on August 16, 2009
Quoting sngalla:


I think you meant John Hope.


Yes I did. As far as brain-farts go, the older you get, the more they begin to stick it up like the normal, gaseous types.
Member Since: August 26, 2006 Posts: 10 Comments: 3753
i believe recon hit Ana COC.

1009mb lower barbs.
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Bill should have an eye tomorrow. Will be easier to see which way he is moving.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting Relix:
Bill is pulling a Georges, the High is too strong.
(edit, oops got mixed up)

since that was 11 years ago, heres the reference:

Member Since: July 29, 2006 Posts: 28 Comments: 1798
GFDL looks to have shifted slightly north with Ana or whats left of it at the time. looks like it brings some of the energy towards northern cuba and south florida
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1096. Michfan
Quoting tropicfreak:


Looks like on visible claudette is trying to form an eye.


COC isn't near closed. Its too open on the west side and recon supports this with very little wind over there.
Member Since: September 7, 2007 Posts: 0 Comments: 1733
I shall explain this forecast:
My prediction

The tracks are of Ana, Bill and Claudette - most following on with the loops, and the track by the NHC.

Area 1: Is an area of convection that developed some small rotation in the past 2 hours - however it might be from the ULL next to it (Area 3).

Area 2: Most likely from the ITCZ, however I see potential.

Area 3: Is the ULL from Area 1 - it gains some convection, a LLC and MLC, and we might have TD 5. Worst Case Scenario: Area 1 and 3 merge. Best Case Scenario: I'm wrong.

Disclaimer: These are my personal predictions - and in no way should you follow these ahead of the National Hurricane Centre in Miami.

Sources:
www.nhc.noaa.gov
http://www.ssd.noaa.gov/goes/east/tatl/flash-vis.html
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Quoting Drakoen:
I see Claudette making landfall near Fort Walton Beach


It looks like she is moving due north/NNW on radar. Wouldn't that take her into Appalachicola??
Member Since: July 17, 2008 Posts: 0 Comments: 1242
1093. Dakster
Quoting Nimitz:
Back again for another season of high drama, sheer boredom, and utter terror. I've lived in hurricane country my whole life, was born and raised in New Orleans, was living there when Audrey destroyed Cameron Parish. I moved to Jacksonville, Fl. not two weeks after Dora put a licking on Jax Beach and Ponte Vedra.

Now I'm back for another season (found the Wunderground last year) and I'll look forward to reading all the comments. I think this is a pretty damn good forecasting asset (once you apply some filters ;) ), and I have a lot of respect for the people here who work hard to share this information with us.

Back to lurk mode, and keeping a sharp eye out for Bill...he looks like a sneaky SOB


I hope you didn't move to Miami. Hurricanes seem to follow you around!
Member Since: March 10, 2006 Posts: 0 Comments: 10462
1092. jipmg
Alright so models are starting to move north with ANA some take it into the bahamas (BAMMS), as expected its moving WNW at the moment based on the satellite, if it somehow pushes north of DR it can be dangerous for SFLA
1091. Relix
Quoting jipmg:


??? ANA is moving slightly more north of west bud


Bah! This! It's the mess of tracks lol. Due North I meant hahaha.

And no... I don't want another Georges in PR =P
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1090. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 30563


Looks like on visible claudette is trying to form an eye.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
hey drake, i'm in fort walton beach. not much going on here. i moved patio furniture while my husband and kids went to crab island. i think they made the right choice. going east of us and may not even rain. kinda of like faye
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Quoting IpswichWeatherCenter:


While I usually trust you 99% Drakoen - any chance of a source?


http://www.hhrecon.com/recon/URNT15/KNHC/
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Quoting Drakoen:
I see Claudette making landfall near Fort Walton Beach


It appears to me Claudette is growing rather than moving. I just hope it stays East of P'cola
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Quoting Michfan:


Im seeing over 5 of them.


Yes, you are right. Highest peak surface wind I could find was 68 mph. Not sure what that translates into in terms of sustained winds, but 5 flags in a row is suggestive of close to Cat 1 winds (74 mph).

On Google Earth, that data got filled in well after the first center fix.
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ana is finally dropping her speed, and seems to be hit here in Puerto Rico more organized ... let see what happen on the next hours..
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Quoting LightningCharmer:
This wasn't the first time a storm formed right over me so to speak. Back in 2007, I can't remember the name of it. It might just have been a TD. You are correct; it is awe inspiring.

By the way saw two waterspouts yesterday off the upper Keys from pre-Claudette.

Keep up the good work Oz.


You're a fortunate weather-spotter! Out of thousands of people in the area, maybe a handful of you knew enough to look up and appreciate what you were watching.

Here on the blog, I know of three who've seen a depression spin up from scratch as we stood looking skyward.

Me, you and PensacolaDoug. Congrats man! You'll have that for the rest of your life now! :)
Member Since: August 26, 2006 Posts: 10 Comments: 3753
http://www.ndbc.noaa.gov/station_page.php?station=apcf1
backs up the idea of a NE shift as C becomes symmetrical. East to now North of east as opposed to a south of east shift that should occur with a westward component
Member Since: August 27, 2008 Posts: 0 Comments: 1497
Quoting Grothar:
Whom are you quoting? I am not an expert, but I do agree with you the models may be off on both systems.


Oh.. forgot to quote that person.. I don't remember lol
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Quoting reedzone:
The models always do this.. They don't really focus on the high.. Ivan (2004) and Dean (2007) VERY good examples.. Ivan was supposed to hit South Florida, but the high kept going and it made it into the heart of the GOM and hit Alabama. Dean was supposed to go north of the Lesser Antilles, in fact Bill is in that very same spot where Dean was at the time it was foretasted to head north.. Instead the high remained strong and pushed Dean west. It's not official yet, lets wait and see what happen through the week.


I completely agree with you reed. Thats why I'm making sure when I deliver updates through my site and Facebook that people don't take their eyes off Bill.
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1078. Michfan
Quoting Drakoen:
I see Claudette making landfall near Fort Walton Beach


The fact that she is moving so slow doesn't bode well.
Member Since: September 7, 2007 Posts: 0 Comments: 1733
1077. WxLogic
Good afternoon... back to CFL from Clearwater... I must say Claudette's wind field has increased some... since I'm registering some breeze conditions around my house.

One thing to note on ANA... if indeed models are correct on a stronger trough, then this would mean the path for ANA will change also and so don't believe its circulation will be over land for too long once it reaches the Greater Antilles... I guess we'll see what the future will hold for ANA.
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1076. Nimitz
Back again for another season of high drama, sheer boredom, and utter terror. I've lived in hurricane country my whole life, was born and raised in New Orleans, was living there when Audrey destroyed Cameron Parish. I moved to Jacksonville, Fl. not two weeks after Dora put a licking on Jax Beach and Ponte Vedra.

Now I'm back for another season (found the Wunderground last year) and I'll look forward to reading all the comments. I think this is a pretty damn good forecasting asset (once you apply some filters ;) ), and I have a lot of respect for the people here who work hard to share this information with us.

Back to lurk mode, and keeping a sharp eye out for Bill...he looks like a sneaky SOB
Member Since: Posts: Comments:
Quoting ralphfurley:
I've been coming here for nearly 5 years and it always amazes me that the same people who said "ignore the models" yesterday are the same ones that say "believe the models" today. ugh. and dont get me started on the "ignore the center line/believe the center line" folks

What is it that bothers you about the ignore or believe center line folk?
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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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