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 flhurricanesurvivor:
does a stall mean a change of direction?


stall means still as in no movement or next to none (in a cane)
Member Since: August 22, 2006 Posts: 2 Comments: 1975
Quoting Patrap:
Claudette seems to have stalled,..



Yep, I can see that on the visible too.
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Why is claudette stalling? Is the high getting stronger or something?
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1472. Relix
Quoting WPBHurricane05:


Gee...imagine that. Ana south of the models.


I have the COC at around 15.1.
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Recon going back, they r over Ft Meyers.
1470. Drakoen
Quoting tennisgirl08:


It's not that the center is exposed, it is that it has relocated further South. Look at the latest satellite loops on the NHC website.


The center is .1 N and .1W of the last vortex message.
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1469. code1
*
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Quoting FLHurricaneChaser:


No tropical storms are fun! I love to be outside in them. I was outside in the middle of Cat 2 Wilma getting smacked around by 100 mph winds. It's a life changing experience.
Might be a life changing experience but could also be a life ending experience.
Member Since: October 9, 2008 Posts: 0 Comments: 8242
Quoting 996tt:
Just back from surfing in Pensacola. Partly sunny and a small swell with 3 foot sets occasionally rolling in. Hoping I can get back out with the short board later today, but pretty mellow here for now.

Funny all those people said Key West blob would nothing yesterday. That should have been easier to predict than Ana or paths of a storm out in the Atlantic . . .


seems like you left too early...
Member Since: August 22, 2006 Posts: 2 Comments: 1975
If Claudette stalls for a bit, it will allow the ridge time to build in from the Atlantic and push her further West towards Mobile/Pensacola.
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Stalling isn't the worst scenario. So Claudette stalls and becomes a strong TS or minimal hurricane. In the long run, maybe should stall long enough to upwell cooler waters.
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Quoting Kat3sNoBreeze:
As I have no idea what time 1200z and 600z are...are these runs pretty up-to-date? It seems that the models are shifting to the left. If her center is actually relocating further south I would assume that these runs would be incorrect? But, if she has not then......? Either way....not a good scenario as it would give her a little more time over water although I would think that she doesn't have THAT much more time to get very large or powerful? Am I thinking correctly y'all?

Link






The GFDL is the best model to follow IMO. All I'm saying.
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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.


yeah, bad is totally relative. i was like wut... but then i got it.

great for formation, bad for folks.
Member Since: August 22, 2006 Posts: 2 Comments: 1975
winds in apalachicola are at 17mph, highest gust at 33mph, 2 inches of rain today
1461. Drakoen
Recon finding 30 knot SFMR winds in Ana
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Now getting the first rains here in Dominica from what was Ana. Can't tell you wind direction as there is none where I am. Dead still.
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hey everyone,
my god, I just got back from vacation and couldn't believe my eyes. The smoke from the fires in Southern California, really hit the Ventura/Ojai area bad. Ash on the cars and thick smoke through the valley.
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1458. 996tt
Just back from surfing in Pensacola. Partly sunny and a small swell with 3 foot sets occasionally rolling in. Hoping I can get back out with the short board later today, but pretty mellow here for now.

Funny all those people said Key West blob would nothing yesterday. That should have been easier to predict than Ana or paths of a storm out in the Atlantic . . .
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does a stall mean a change of direction?
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1456. IKE
Quoting SOUTHFL43YRS:

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


I would if I had one....

Can't afford it...too many other pressing bills.

I called my mom who lives here in the same town. She didn't even know about it.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Drakoen:
The center of Claudette is a little expose on visible imagery


It's not that the center is exposed, it is that it has relocated further South. Look at the latest satellite loops on the NHC website.
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Quoting JRRP:


Gee...imagine that. Ana south of the models.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
1453. Michfan
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I am still amazed how I underestimated this system.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
1451. Patrap
Claudette seems to have stalled,..

Member Since: July 3, 2005 Posts: 414 Comments: 125613
1450. Drakoen
Quoting MississippiWx:


Where?? I don't see it. I'm not saying it's not there, I just don't see it! :-/


I can see the center perfectly on visible imagery.
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Quoting Drakoen:


Its a tropical storm. Stay indoors and you'll be fine.

Ike and go back a few years. Were just having fun. LOL!
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1448. JRRP
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1447. jpsb
Center relocation is very common, in newly forming gulf storm, very common. Not saying this is happening but chances for a new center forming are good.
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Quoting TexasHurricane:I wonder when the 2pm advisory will be out for Bill??



there wont be a 2pm update for bill in tell bill come to 50W in then olny 6hrs update on bill
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Quoting Drakoen:


Its a tropical storm. Stay indoors and you'll be fine.


No tropical storms are fun! I love to be outside in them. I was outside in the middle of Cat 2 Wilma getting smacked around by 100 mph winds. It's a life changing experience.
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Lots of wind, rain, and heavy surf (for us) here at St. Teresa Beach, FL (Alligator Point area). Thanks for all the updates -- be safe everyone!!
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Shear is going to increase for Claud not sure how much she will strengthen..
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1440. Drakoen
The center of Claudette is a little expose on visible imagery
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Quoting IKE:


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


Where?? I don't see it. I'm not saying it's not there, I just don't see it! :-/
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Quoting TexasHurricane:
I wonder when the 2pm advisory will be out for Bill??


Never.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Looks like Bill is already north of the forecast points
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heh funny in a way how not many people were paying close attention to "that Keys blob" yesterday anyways good luck to everyone in Claudette's path. Though minor you shouldn't let your guard down still. Stay safe
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Claudettes center doesnt look right compared to where convection is firing up?
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As I have no idea what time 1200z and 600z are...are these runs pretty up-to-date? It seems that the models are shifting to the left. If her center is actually relocating further south I would assume that these runs would be incorrect? But, if she has not then......? Either way....not a good scenario as it would give her a little more time over water although I would think that she doesn't have THAT much more time to get very large or powerful? Am I thinking correctly y'all?

Link




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Has anyone developed a molecular transportation device that will work from New Mexico to the Florida Panhandle?

If yes, I'd volunteer to test it today for you.
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1432. Drakoen
Quoting SOUTHFL43YRS:

Ike, you are about to get hammerd.
Get the generator gas up.


Its a tropical storm. Stay indoors and you'll be fine.
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1431. Sting13
You guys keep saying its going to be a "fish" storm, anyone remember about canada up here? half the models have the storm hitting nova scotia *sigh*
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I wonder when the 2pm advisory will be out for Bill??
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Quoting alpha992000:
SerialTeg: I'm in the Rio Piedras area.





nice my msn is serialteg@gmail.com if u have one...
Member Since: August 22, 2006 Posts: 2 Comments: 1975
Quoting HurricaneGeek:
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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1427. Patrap
Member Since: July 3, 2005 Posts: 414 Comments: 125613
http://www.ssd.noaa.gov/goes/flt/t3/wv-l.jpg

shows COC reformation at 85-28
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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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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.