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 hurricane23:
Thankfully its all bark no bite so far this season. A few weak td's which could be rain producers and mighty bill should stay out to sea.

Adrian


????
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i think ANNA is a open wave now
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
423. Prgal
Quoting raggpr:
Thanks Prgal! I already fill up my car tank!.

I did the same thing yesterday. I am ready for whatever is on its way. The waiting is what kills most of us lol...the uncertainty of the track etc. But oh well...nothing we can do about that. Good luck!
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Quoting Drakoen:
Please don't post all the recon observations. We know where they are.


on the /tropical page?

anyway... the recon is reporting high pressures... don't get it
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Check out the new Klystron Radar out of Tampa

http://www.baynews9.com/Klystron9.html
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As noted by blake, bill continues to display a spectacular curved band pattern on visible imagery.You can see it here on this large 1km image.

Bermuda might want to keep an eye out on bill.
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Quoting Funkadelic:
When Bill is by the Bahamas, the high to the right of him could push him back to the west. Drakoen what is your take on that? Because I remember StormW saying something like that.
me too, Something like an Andrew 92' track.
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IMHO, I enjoy and appreciate the graphics because I'm (embarrassingly) still on dial up. Also, I thank all for their observations as I can not navigate back and forth from various outside weather sites easily. Thanks.
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Please don't post all the recon observations. We know where they are.
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BERMUDA HERE I COME LOOKS LIKE MID WEEK.
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Quoting P451:


Valid 12Z Saturday August 22



Gulf Coast = remnants of Ana
Bahamas = Bill
You can note the cold front digging south.





tyvm p451

that statement is completely unreadable if you dont know what tyvm stands for... lol
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413. amd
i will say this about td4, its center is very easy to track on radar. And, it definitely looks like it hit some sort of wall in its northerly movement.
Member Since: August 29, 2005 Posts: 0 Comments: 1024
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Quoting BrandiQ:


What are the chances of that happening?


Brandi I would give it about 20 maybe even 30% of Bill hitting South FL.....

But I do want to make sure that it is still very early and Bill
could go anywhere at this point....

Taco :0)
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by the way is it me or did ANA open to to be wave now then a name storm i think it lots its low-level center and now a open wave too me you cant even tell if it has a low-level center any more
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Thanks Prgal! I already fill up my car tank!.
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Quoting LightningCharmer:
With due respect, I actually like the graphics and animations. Often when on the road, I read this blog on a cell phone that does not support flash or java. It also takes forever to link away from the site, and then return to the blog and try to find your place on a cell phone browser.

I don't always blog on a cell phone but when I do these images animated and static make it much easier at least for me.

No problem at all being here from by blackberry.
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stormno your propaganda is hilarious. Hurricane???? and Houston????
Member Since: August 25, 2008 Posts: 0 Comments: 17
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NOAA Tallahassee, FL Radar Long Range Reflectivity
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Quoting mobilegirl81:

A coastal dancer.


The shimmy?
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It seems that Bill may recurve out to sea with the present models runs that are leaning on this solution.
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ListenerVT, the key for Bill and the Northeast is the strength and timing of the trough forecast to come into the East. If this trough is stronger and more negative then the storm will move further north and west up the coast.
Member Since: October 21, 2008 Posts: 243 Comments: 3696
Quoting CycloneOz:


Sweet... :) I'm sure I'm on a few lists, it's actually a point of pride for me! :)

I got on someone's iggy list last night for not falling in step and bowing to stromno's met prowess. Yay, whatever.
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Quoting CycloneOz:


Sweet... :) I'm sure I'm on a few lists, it's actually a point of pride for me! :)

lol
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Ana have been giving a really good fight! But she seems to be losing Saharan Dust -vs- Ana! who wins?
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Live Decoder Reports

theres two planes heading out to ana and td4 as we speak....use the link to watch live...should be interesting as to what each one sees...
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396. CUBWF
Good morning. Can any of you show me where the trough and the weakness of the high is at this time, and which is the best sat picture to see it. I don't know if you can understand my question. Forgive my english. Thanks in advance.
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395. Prgal
Quoting raggpr:
I live here in PR. I should expect some tropical stroms winds from Ana since the wind range extend mostly to the northern part of the storm and Ana is expected to past just a few miles south of the island. Any opinions?

I think we should pay close attention to both storms. These tracks will go back and forth and conditions can change quickly. We should all be ready for a storm during hurricane season with food and water stored (you know that with a breeze the power goes out lol). So in my opinion, lets just keep an eye and be ready just in case. Tomorrow morning we should have a better idea of what to expect.
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Quoting Babsjohnson:


I have to agree. This is a freaky storm.

A coastal dancer.
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Quoting raggpr:
I live here in PR. I should expect some tropical stroms winds from Ana since the wind range extend mostly to the northern part of the storm and Ana is expected to past just a few miles south of the island. Any opinions?


by all means yes... even more so in the south coast

after all we're only 35 miles south to north, but. ana's been tracking steadily around the 15N and hasnt done the NW curving so. it could very well keep south and end up not affecting us as much because of that. keep monitoring
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Quoting TStormSC:

US Drought Monitor
Link
Thank you! Didn't realize we were in such good shape this year.
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Quoting Weather456:
alot of potential tropical storm forced winds

STORM CHASERS HEAD TO BERMUDA
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it looks too me on the rader that TD 4 is moveing WNW/W wish may give it more time overe open waters
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
The last satellite images seems to be showing Bill going more to the west maybe even a little bit to the southwest, but this may be just the thunderstorms moving around the center. For now I will say that it is moving westward.
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Quoting taco2me61:
Canesrule1
With all due respect that is what I see as of right now but it is still early and of course anything can happen.... Bill could miss the pull and end up going SW and hit the southern East coast of FL....

Taco:0)
WOW!!! U just dropped a bomb on me, LOL, never know, thanks a lot for informing me.
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Quoting taco2me61:
Canesrule1
With all due respect that is what I see as of right now but it is still early and of course anything can happen.... Bill could miss the pull and end up going SW and hit the southern East coast of FL....

Taco:0)


What are the chances of that happening?
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TD4 looks very nice on radar and a few hours away from landfall.
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So Tamazian says it is possible that Bill can hit the Northeast does anyone thinks this is possible too?
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384. IKE
Quoting MississippiWx:
Ike, you still around? Check out the latest radar loop. Appears that the center is headed on a WNW course at the moment.

Link


WNW to maybe NW to me.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Funkadelic:


Consider the NOGAPS the KNOWCRAP, this model never seem's to understand steering out there. I have never given that model much attention.


no, its the model that doesnt take NOCRAP. lol im out for a while
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Quoting twhcracker:


thank god you cant spell, i thought it was for real!


Cracker, no mistakes here. Maybe your spell check is in German?
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Quoting JRRP:
i am surprised that ana is a tropical storm yet


maybe theyre just reluctant to lose the name, like ive read before

forecaster NHC said he was "generous" with the storm

this like 97l has been a persistent one. i believe i have a special attachment to ana
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Canesrule1
With all due respect that is what I see as of right now but it is still early and of course anything can happen.... Bill could miss the pull and end up going SW and hit the southern East coast of FL....

Taco:0)
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Latest Dvorak i could find (about 3 hours 45 minutes ago)

16/1145 UTC 28.2N 84.2W T2.0/2.0 04L
16/1145 UTC 12.2N 37.7W T3.0/3.0 BILL
16/1145 UTC 14.5N 54.9W T1.5/2.0 ANA

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Quoting floridafisherman:
cyclone oz...

how many times are you going to post the same thing?

you are now added to my ignore list.



Sweet... :) I'm sure I'm on a few lists, it's actually a point of pride for me! :)
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Quoting WatchingThisOne:


I doubt that. TD4 is in an area of high SSTs, but of very low oceanic heat content. Any effect will be very short term. Plus it's a small storm.


The entire idea is that it is a relatively minor storm over an area with low heat potential and high temperatures. It's easier to drop the SST when there is not nearly as much warm water to back it up. And, I am talking (relatively) short term: Just in case A or B make it into the gulf somehow.

It would not make the environment unfavorable. But, at least it might limit the potential for a passing storm to explode on the initially large delta T alone.
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I live here in PR. I should expect some tropical stroms winds from Ana since the wind range extend mostly to the northern part of the storm and Ana is expected to past just a few miles south of the island. Any opinions?
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Quoting Babsjohnson:


I have to agree. This is a freaky storm.


thank god you cant spell, i thought it was for real!
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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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