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 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
Quoting Drakoen:
Claudette has slowed down and has the potential to become a strong tropical storm.
yup, we could have 50+ knot winds at 2PM.
kind of creepy, Clauddete is looming just off the coast and all these pictures of dark clouds were on TWC
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Quoting champagnedrmz:
Last year google earth had the recon add on. Do they still have that this year and if so, does anyone have a link to it? Thank you in advance.


You can get the .kml files here:

http://www.guiweather.com/kml.html
Member Since: July 15, 2005 Posts: 3 Comments: 1267
Quoting CaneWarning:
We are lucky Claudette is as close to shore as she is...she could've been a big problem if she had a day or two more over the GOM.


i was thinking the same,


30C waters ouch!
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Funkadelic:


No, I will call it an improvement. If she holds some convection through D-Min, Then she could make a "comeback" please do not accuse me of a word I did not say. I simply said looking better and north of her forcast points. :)
well it is a slight improvement over the past 6 hours, but if DMIN and DMAX affects a system it shouldn't be a tropical storm, straight up.
Quoting fire635:


I agree.. its seems like shes slowing quite a bit actually


She wants to play in the water a bit longer.
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Quoting serialteg:


http://tropicalatlantic.com/recon/ge/Recon_Data_for_the_Atlantic_Basin.kmz


Again thank you.
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Patrap you have mail
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We are lucky Claudette is as close to shore as she is...she could've been a big problem if she had a day or two more over the GOM.
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Quoting Drakoen:
Claudette has slowed down and has the potential to become a strong tropical storm.


I agree.. its seems like shes slowing quite a bit actually
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Quoting CaneWarning:
I really wish WS was here so we could get his expert opinion.


LOL!!!!!!!!!!!!!!!!
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Quoting Weather456:


she should be locked up for indecent exposure.
lol
Member Since: October 9, 2008 Posts: 0 Comments: 8373
759. IKE
Quoting KEEPEROFTHEGATE:
i posted ts claudette 45 mins ago 15 mins before NHC cane your a little late

try and keep up will ya

just j/k
lol

anyone hear from ike i hope he's porch will be alright


I'm here.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Seems Claudette is driven extremly by the GOM SST's.
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Ana prolly trying to form a new coc north of the 11am plot under the convection that's firing.

at least it looks that way on visible imagery.
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Eye beginning to develop:
Now claudette is a lovely lady, as she is well dressed, doesnt have impress Bill at all.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Patrap:
MESSAGE DATE: AUG 16 2009 13:14:39 DUE TO THE EXPECTED RAINFALL FROM TD#4 WHICH IS FORECAST TO BECOME TROPICAL STORM CLAUDETTE, WE HAVE CHANGED THE Z-R RELATIONSHIP ON THE KTLH RADAR TO TROPICAL.




What is the Z-R relationship?
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Quoting ALCoastGambler:
Patrap, Ike Looks like she may be riding the "H" around. I may be wrong but that's what it's looking likt to me. Which moves her near Pensacola/Mobile



..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...
Member Since: July 3, 2005 Posts: 424 Comments: 128347
Claudette has slowed down and has the potential to become a strong tropical storm.
Member Since: October 28, 2006 Posts: 57 Comments: 30494
Quoting JRRP:
it is clear ... Bill is moving WNW


Im thinking due west... the convection is playing with your eyes... the center appears to be on a western track right now imo
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Quoting Funkadelic:
Everyone is focused on Bill and now the C storm (Which should be cause claudette is close to landfll) But Anna is looking better, and Is well north of her forcast points.

Anyone else notice this??


Yes. It also looks like it has switched COCs, almost, from that southerly one to the one that is further north.
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Quoting champagnedrmz:
Last year google earth had the recon add on. Do they still have that this year and if so, does anyone have a link to it? Thank you in advance.


http://tropicalatlantic.com/recon/ge/Recon_Data_for_the_Atlantic_Basin.kmz
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Quoting JRRP:
it is clear ... Bill is moving WNW
I don't see it. Looks W to me.
Member Since: October 9, 2008 Posts: 0 Comments: 8373
This is what it says for Bill on the tropical page.

Wind: 60 MPH — Location: 12.1N 38.4W — Movement: WNW

Looks to still be moving WNW unless that has changed? Anyone still thinking it won't take that big turn to the north?
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Quoting chsweatherintern2009:
Breaking News we now have Claudette
i posted ts claudette 45 mins ago 15 mins before NHC cane your a little late

try and keep up will ya

just j/k
lol

anyone hear from ike i hope he's porch will be alright
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Quoting stormwatcherCI:
She really is a fighter though. Just doesn't want to give up.


she should be locked up for indecent exposure.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
I really wish WS was here so we could get his expert opinion.
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Someone posted this link earlier, but it gives you a cam of St Geroge Island as well as the radar.

http://www.beachview.com/st_george_is_640.htm
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Quoting JRRP:
it is clear ... Bill is moving WNW


imo it is jogging westward in the latest frames
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Quoting canesrule1:
LOL, look at the AVN u say that is a comeback, lol:
No-one said it is a comeback. Said it she was trying to make a comeback.
Member Since: October 9, 2008 Posts: 0 Comments: 8373
737. afj3
Could Ana take a track similar to Ernesto in 2006?
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Last year google earth had the recon add on. Do they still have that this year and if so, does anyone have a link to it? Thank you in advance.
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Quoting Weather456:


that is a convergence line in the trades, and it is being enhance but the pressure gradient between Ana and the subtropical ridge.
thanks
734. Relix
I've been saying Ana was making a comeback and north of the points for like 2 hours now =(. I just came back and saw that. Bill doesn't convince me on the WNW track either!
Member Since: August 3, 2006 Posts: 0 Comments: 2723
MESSAGE DATE: AUG 16 2009 13:14:39 DUE TO THE EXPECTED RAINFALL FROM TD#4 WHICH IS FORECAST TO BECOME TROPICAL STORM CLAUDETTE, WE HAVE CHANGED THE Z-R RELATIONSHIP ON THE KTLH RADAR TO TROPICAL.


Member Since: July 3, 2005 Posts: 424 Comments: 128347
731. JRRP
it is clear ... Bill is moving WNW
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National Weather Service Enhanced Radar Image Loop - Tallahassee, FL RadarBand with heavy rain soon to strike coast.
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SFMR finding those TS winds in Claudette
Member Since: October 28, 2006 Posts: 57 Comments: 30494
Hello ya'll. I've been following the posts. Very muggy with still winds here in SW Escambia County. Had 1.26 inches of rain around 0400 this morning. I expect we'll get some wind later from Claudette but at this point I don't think it'll get bad. BUT living along the gulf coast all my life I don't ever let my guard down during 'cane season; thanks for all the great links and images - BTW, Patrap - like your pic! - I work right next to the Blue's hangar on NASP.
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Quoting Funkadelic:
Everyone is focused on Bill and now the C storm (Which should be cause claudette is close to landfll) But Anna is looking better, and Is well north of her forcast points.

Anyone else notice this??
LOL, look at the AVN u say that is a comeback, lol:
725. afj3
Quoting chsweatherintern2009:
Breaking News we now have Claudette

Yup
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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.