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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725. afj3
Quoting chsweatherintern2009:
Breaking News we now have Claudette

Yup
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Quoting chsweatherintern2009:
Breaking News we now have Claudette


You are about 30 minutes too late.
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Quoting Weather456:
Frist signs of Ana, mid-level altocumulus clouds overhead

stormwatch,

if she continues to sustain that convection, then I would say comback, not right now though
She really is a fighter though. Just doesn't want to give up.
Member Since: October 9, 2008 Posts: 0 Comments: 8424
Quoting rxse7en:
Sorry, mine's from Japan.

http://www.the-webcam-network.com/Florida-USA/Apalachicola/2993597.html


LOL..that was funy!
Member Since: Posts: Comments:
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
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Quoting rwdobson:
Interesting the NHC is naming Claudette based on the radar. I noticed a core of higher winds on the Wunderground radar, but I'm never sure how much to trust the speed numbers from the radar images...looks to me like a decent sized area 36 kts according to radar.


the google earth air recon map is a cool thing to have, the plane is heading into claudette i believe but yes. i believe it hasnt arrived yet and naming it before is a little wtf-ish.

epic wait... latest 16:37z data indicates 38mph surface winds but high 1013mb SP
Member Since: August 22, 2006 Posts: 2 Comments: 1988
Quoting Drakoen:
The weather channel has two scenarios for Bill. The trough recurves it out to sea or it slips under the high the trough has (Ike 2008)what we call "bust the trough."


Yup I saw that one there.
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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??


I mentioned that
Member Since: October 28, 2006 Posts: 57 Comments: 30614
717. bcn
Sorry, what is the loop at 25N-70W?

Thanks.
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Quoting canesrule1:
What is that north of Ana, looks like a tropical wave trying to form, or is it a flare-up by an ULL:


that is a convergence line in the trades, and it is being enhance but the pressure gradient between Ana and the subtropical ridge.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting jurakantaino:
TWC , agree that Ana once again making her Pm come back as yesterday this time with WARMER WATERS, LESS SHEAR, still dealing with dry hair and high speed movement (23mph) which may hindered its further development...


Ana's almost moving as fast wilma when she went through Florida. Thats the fastest moving TS i've ever seen not being influenced by anything but steering.
Breaking News we now have Claudette
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Quoting Drakoen:
The weather channel has two scenarios for Bill. The trough recurves it out to sea or it slips under the high the trough has (Ike 2008)what we call "bust the trough."


Recurve is more likely in my opinion.
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Quoting HurricaneKyle:
Disorganized Ana, but a possible threat to the GOMEX if it survives its Caribbean trip.


Bill, gaining strength. Getting close to hurricane status.


Claudette gaining strength rapidly.
Bill will probably begin to develop an eye before 5PM
711. amd
Quoting jurakantaino:
TWC , agree that Ana once again making her Pm come back as yesterday this time with WARMER WATERS, LESS SHEAR, still dealing with dry hair and high speed movement (23mph) which may hindered its further development...


something about Ana worries me. If the system somehow goes just south of Hispaniola and Cuba, and survives the dry air and shear, it can ramp up quickly in the western Caribbean and southern gulf of Mexico.
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Quoting clwstmchasr:
this storm came out of no where and none of the mode runs where forcasting it then boom you get Claudette out of no where

It is isteresting that none of the models developed this system. However, Dennis Phillips who is a very good TV met called it. On Thursday night, his model showed a storm forming in just about the exact location where TD4 formed. He said that he would not be surprised that a TD or weak TS formed off the west coast of Fl.


ok i do not think this came out of nowhere... models have been developing things in gom i believe, the wave was being tracked for days on this board and yesterday we were on top of the rotation thanks to our florida and nearby forumcasters.

:D
Member Since: August 22, 2006 Posts: 2 Comments: 1988
Interesting the NHC is naming Claudette based on the radar. I noticed a core of higher winds on the Wunderground radar, but I'm never sure how much to trust the speed numbers from the radar images...looks to me like a decent sized area 36 kts + according to radar.
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708. IKE
Quoting Patrap:



Just dont let her spend to much time lolly gagging along the Coast,best to get this un Inland ASAP.


Agree.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
The models seem to be clustering around a NNW course.
Member Since: July 15, 2005 Posts: 3 Comments: 1269
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??
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ANNA is makeing a slow come back
Member Since: May 21, 2006 Posts: 5091 Comments: 115351
Quoting IKE:


See what I can do for you.

Claudette is about to go west of Apalachicola latitude.


No- another guy - and he repeated that again a few minutes ago. The models (with the exception of the UK Met) see Bill being picked up by that trough; the UK Met does not- or didn't factor in that variable to trend the 5 day path.
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The weather channel has two scenarios for Bill. The trough recurves it out to sea or it slips under the high the trough has (Ike 2008)what we call "bust the trough."
Member Since: October 28, 2006 Posts: 57 Comments: 30614
702. IKE
Pressure really rising now at the buoy 105 NM WNW of Tampa....

system moving west/NW away from here...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Funkadelic:
In my eyes bill is moving NW.. Dont know what you guys are seeing. It is north of the forcast points. Ecpecte the NHC cone to shift even further north and east at 5pm.


Well, Bill's center is still about 200 miles south of the southernmost Cape Verde islands, which is about where he emerged from Africa.
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A tropical storm can be just as deadly as a hurricane google Fay or Allison if you need more explanation, best to take one seriously especially if you live in a flood zone.


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What is that north of Ana, looks like a tropical wave trying to form, or is it a flare-up by an ULL:
Quoting winter123:
Anyone have a camera from Appilachicola area?
Sorry, mine's from Japan. :D

http://www.the-webcam-network.com/Florida-USA/Apalachicola/2993597.html
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TWC , agree that Ana once again making her Pm come back as yesterday this time with WARMER WATERS, LESS SHEAR, still dealing with dry air and high speed movement (23mph) which may hindered its further development...
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Quoting IKE:


Similar to Elena's track after it turned back from the west coast of Florida...



Just dont let her spend to much time lolly gagging along the Coast,best to get this un Inland ASAP.
Member Since: July 3, 2005 Posts: 426 Comments: 129090
ok I'm out for a while.... Need to go get a few more batteries just in case we lose power.... Heck you never know....

We will lose power here in Mobile if it is raining in MO so I need to be ready LOL....

Everyone play nice and will beack later....

Taco:0)
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Disorganized Ana, but a possible threat to the GOMEX if it survives its Caribbean trip.


Bill, gaining strength. Getting close to hurricane status.


Claudette gaining strength rapidly.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting Patrap:
TS Claudette has slowed some in Forward speed..wnw at 273 degrees,..we dont want her to go Null in steering now..



Not good, not good at all.
Quoting Vortex95:
Quoting rmbjoe1954:


Thw Weather Channel seems to think the trough MAY not be strong enough or move south in time to pull Bill northward.

As much as they suck now Steve Lyons is still there, he say that?


I think Bill will be pulled North But not before it effects the Outter Banks of NC or even Bermuda.

Either way, I don't think Ana or Bill will either be a complete fish storm...some land will be effected.
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Quoting extreme236:


Clearly not effecting it enough to prevent it from strengthening...almost a hurricane.
Yup
CAB lol

Member Since: July 24, 2005 Posts: 407 Comments: 19076
689. JLPR
Quoting Weather456:
Frist signs of Ana, mid-level altocumulus clouds

stormwatch,

if she continues to sustain that convection, then I would say comback, not right now though


Anna is looking a little better but it is so small! xD
and is it me or is Anna above its forecast points, was watching the forecast track on the SSD floater ans it seems to be below it now
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The Tropical Wave behind bill.

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Quoting Drakoen:
Interesting is that none of the global models forecasted for Claudette to develop before. Could possibly be because of how small a circulation it has.

probably I know nobody expected Marco to form last year
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TS Claudette has slowed some in Forward speed..wnw at 273 degrees,..we dont want her to go Null in steering now..

Member Since: July 3, 2005 Posts: 426 Comments: 129090
Quoting Funkadelic:
In my eyes bill is moving NW.. Dont know what you guys are seeing. It is north of the forcast points. Ecpecte the NHC cone to shift even further north and east at 5pm.
It has just done a NW wobble, it is expected to continue WNW, the Cone at 5 should probably do a minor shift northward.
683. IKE
Quoting Patrap:



Ike your Claudette has gone to 273 true last 35 minutes,around 10mph


Similar to Elena's track after it turned back from the west coast of Florida...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting 50PastTheHour:
Have you not looked at water vapor loop? that is very dry air ahead and bill's circulation is drawing it in.


Clearly not effecting it enough to prevent it from strengthening...almost a hurricane.
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Depending on the recon data, I believe we could see Claudette be near hurricane status at landfall.
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Quoting rxse7en:
G'morning, Aqua. Is that trough situated over Missouri now?


hiya rx7. Been seein' ya postin' on occasion, good to see ya. Your question? there or a little off to the NW of there. Still wondering what affect claudette will have on it. Timing, strength makes all the difference.
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Quoting ConchHondros:
Where has Floodman been?


he was on thursday for a time.
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Quoting 50PastTheHour:
Have you not looked at water vapor loop? that is very dry air ahead and bill's circulation is drawing it in.
I've been told that Bill has an anticyclone placed over it.
Quoting FLHurricaneChaser:
I told you all Claudette would be nothing more than a 40kt weak TS.


Oh... all bow to hurricanechaser
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Quoting Funkadelic:
In my eyes bill is moving NW.. Dont know what you guys are seeing. It is north of the forcast points. Ecpecte the NHC cone to shift even further north and east at 5pm.


Its the way the convection is wrapping around the center. Bill is moving WNW.
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675. IKE
Quoting TStormSC:
OK Ike, go empty the rain gauge and keep us up to date. How 'bout grabbing that lady and sending some rain NE.


See what I can do for you.

Claudette is about to go west of Apalachicola latitude.
Member Since: June 9, 2005 Posts: 23 Comments: 37858

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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.