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 CaneWarning:


It's very unlikely.


Well say that then; don't say no. You know no more than any of us what will ultimately happen with any of these storms.

If we all knew what was going to happen, there'd be no need for a forum, right?
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Quoting SouthALWX:
http://www.ndbc.noaa.gov/station_page.php?station=sgof1


TS surface wind measurement, plus some understandable pressure tendencies.
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Does anyone think that there is a chance that Ana could to a northern path and possibly affect the east coast of Florida?
Thanks
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Quoting canesrule1:
Recon has found 45 knot wind in the COC of Claudette at the surface


I've got 43.1 knots (~ 49.5 mph)
Tropical Storm
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Quoting szqrn1:
I am trying not to stay clued to the computer!
The local classic rock radio station weather girl just gave our forcast here for biloxi/gpt... 50% chance of rain ... 60% tomorrow "looking good right now" NO mention of Claudette in GOM whatsoever!! OMG really? LOL!


That makes sense. It should'nt be anywhere near that location.
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970. srada
Quoting extreme236:
GFS run shows a powerful Bill moving east of the US coast


Hi

Can you post the link?
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yeah, by that map it definitely looks to keep it on a westward track. Unless of course i'm not reading it right and since I am somewhat new here that could be possible. Who thinks this north track they have is way off?
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I'm impressed at ana. She has hung in there even through the wind shear and dry air. Now that shear has lessened all she has to deal with is dry air, which is decreasing somewhat.
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I'm sorry guys but alot can change after 5 days, did with Dean in 2007. This is not a guaranteed recurvature yet. Listen, I can see this turning out to sea like all of you boldly proclaim, but not until it passes south of Bermuda. It will be a close call recurvature for the USA and the Carolinas to Maine needs to closely monitor this situation. A Gloria type storm is not out of the question. Or something like Hurricane Edouard in 1996 where it clipped New England, I can see that happening as well. Don't be so confident be prepared just in case you all are oh I dunno.. wrong. Even Dr. Masters didn't jump on the fish wagon just yet, things change.
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Flight level winds are 42knot max on Ana with 25knot SFMR
Member Since: October 28, 2006 Posts: 57 Comments: 30690
I am trying not to stay clued to the computer!
The local classic rock radio station weather girl just gave our forcast here for biloxi/gpt... 50% chance of rain ... 60% tomorrow "looking good right now" NO mention of Claudette in GOM whatsoever!! OMG really? LOL!
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Quoting StormW:
Good afternoon!

Good Evening
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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 16th day of the month at 17:14Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 04

Mandatory Data...

Observation Time: Sunday, 17:15Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 29.2N 84.0W
Location: 88 miles (142 km) to the S (169°) from Tallahassee, FL, USA.
Turbulence: Light
Conditions Along Flight Route: In the clear
Pressure Altitude: 760 meters
Flight Level Wind: From 150° at 45 knots (From the SSE at ~ 51.7 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 18°C
Flight Level Dew Point: 8°C
Weather (within 30 nautical miles): Thunderstorm(s)
925 mb Surface Altitude: 819 geopotential meters

Optional Data...

Estimated Surface Wind: From 170° at 40 knots (From the S at ~ 46.0 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 39 knots (~ 44.9mph)
Member Since: September 7, 2007 Posts: 0 Comments: 1746

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Tropical Storm CLAUDETTE
Recon could probably stay in Claudette for a while...not like its too far from base.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
It looks like Bill will become a major hurricane but hopefully miss the U.S. entirely, still a little early to say that.

Ana is so tiny that if its circulation doesn't expand, the islands of Hispaniola and/or Cuba should be enough to cause it to dissipate into more more than a disturbance. The area of showers to the NNW of Ana and east of the upper-level low approaching the Bahamas actually looks more impressive than Ana.

Claudette to be was a surprise and if it had been on a course where it would stay over water an additional day or so, it could have easliy become a hurricane. Thankfully, it will not. Still, the FL panhandle is in for some rough weather this afternoon and evening.
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Quoting HurricaneKyle:
Flight level winds
54 knots
(~ 62.1 mph)

Surface winds
43.1 knots (~ 49.5 mph)
Tropical Storm



wish storm?
Member Since: May 21, 2006 Posts: 5091 Comments: 115436
Flight Level winds certainly support a 45-50 MPH Claudette.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting Alockwr21:


Nope? You know what's going to happen with it?


It's very unlikely.
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Estimated Surface Wind: From 170° at 40 knots (From the S at ~ 46.0 mph)

Surface Wind Speed (likely by SFMR): 39 knots (~ 44.9mp
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51MPH winds at the surface of Claudette, 41MPH winds at the surface of Ana.
Quoting CaneWarning:


Nope.


Nope? You know what's going to happen with it?
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951. Relix
Bill is not going north any time soon. Maybe by late tomorrow? Tracks will shift south I am guessing.
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Flight level winds
54 knots
(~ 62.1 mph)

Surface winds
43.1 knots (~ 49.5 mph)
Tropical Storm
Member Since: August 10, 2009 Posts: 3 Comments: 672
Quoting jpsb:
Quoting CycloneOz:
"Hardly anyone wanted to even acknowledge the Key West disturbance yesterday..."
Speak for yopurself, I was all over that blob yesterday and the evening before.


Yeap! We are lucky that she is not going to have much more time to develop. It could have been a completely different situation!
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Quoting weatherfan92:


It is officially Claudette. Look at the NHC site.

Yes i see that.
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 16th day of the month at 16:55Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 02
A. Time of Center Fix: 16th day of the month at 16:43:20Z
B. Center Fix Coordinates: 29°04'N 84°56'W (29.0667N 84.9333W)
B. Center Fix Location: 88 miles (142 km) to the SSE (150°) from Panama City, FL, USA.
C. Minimum Height at Standard Level: 754m (2,474ft) at 925mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 35kts (~ 40.3mph)
E. Location of the Estimated Maximum Surface Wind: 11 nautical miles (13 statute miles) to the WNW (285°) of center fix
F. Maximum Flight Level Wind Inbound: From 72° at 28kts (From the ENE at ~ 32.2mph)
G. Location of Maximum Flight Level Wind Inbound: 25 nautical miles (29 statute miles) to the WNW (302°) of center fix
H. Minimum Sea Level Pressure: 1008mb (29.77 inHg) - Extrapolated

I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 767m (2,516ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 23°C (73°F) at a pressure alt. of 766m (2,513ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Level: 925mb (If this vortex is from mid 1990's or earlier 925mb might be incorrect. See note.)
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1.5 nautical miles
Remarks Section:
Maximum Flight Level Wind: 28kts (~ 32.2mph) in the northwest quadrant at 16:34:30Z
Maximum Flight Level Wind Outbound: 54kts (~ 62.1mph) in the northeast quadrant at 16:44:40Z
Sea Level Pressure Extrapolation From: 925mb
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Quoting reedzone:


Don't be so bold, things can change in a heartbeat. Even Dr. Masters said NOT to be confident on it turning out to sea just yet. Give it a few days. I'm still saying that the East Coast still needs to watch this (Carolinas to Maine)


Especially the carolinas, they have been more hurricane prone.
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946. jipmg
hey guys dont let this catch you offguard, check out the visible for ANA, it seems its moving well north of the forecast track, might have a direct impact on puerto rico
Quoting tropicfreak:


And cuba too. Parts of it are mountainous.


I'm talking about it possibly getting into the Bahamas.
Member Since: October 28, 2006 Posts: 57 Comments: 30690
If Anna makes it, looks to be north of forecast track. May follow the ull just east of the Bahamas across Fl. Might be the one to watch.
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Quoting Patrap:
Seems maybe the old core,albeit small,may be giving way to a newer one thats forming around it..



Almost looks like an eyewall forming the N of the COC. Humberto had that. This thing might be going up fast.
Member Since: August 10, 2009 Posts: 3 Comments: 672
anna a mona passage runner a bunch of dominicans have drown out there trying to reach p rico
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Recon has found 45 knot wind in the COC of Claudette at the surface
Quoting WPBHurricane05:
Bill isn't going out to sea anytime soon until high pressure breaks down. WNW/W for today and tomorrow.



thak you sir
Member Since: May 21, 2006 Posts: 5091 Comments: 115436
Quoting jpsb:
Quoting CycloneOz:
"Hardly anyone wanted to even acknowledge the Key West disturbance yesterday..."
Speak for yopurself, I was all over that blob yesterday and the evening before.


I count you as one of the few who did. Chill...
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Ana is now currently at

1011.7 mb
(~ 29.88 inHg)
From 90° at 37 knots
(From the E at ~ 42.5 mph)

This is from Recon.
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Quoting Patrap:
Seems maybe the old core,albeit small,may be giving way to a newer one thats forming around it..



Which would coincide with its convection expanding. This will also result in its wind field expanding as well.
Member Since: September 7, 2007 Posts: 0 Comments: 1746
Quoting leftovers:
danny hung around in mobile bay for awhile
Isnt Danny the one that sucked all the water out of the bay watching from Bay minette closely
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Quoting futuremet:
Out-to-sea


Could spell trouble for Bermuda though, this model has it passing just to the west of the island
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Quoting CaneWarning:


Nope.


Don't be so bold, things can change in a heartbeat. Even Dr. Masters said NOT to be confident on it turning out to sea just yet. Give it a few days. I'm still saying that the East Coast still needs to watch this (Carolinas to Maine)
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Quoting Drakoen:
Ana may come over the northern Lesser Antilles with it's current motion. If it can avoid Hispaniola she will be a player


And cuba too. Parts of it are mountainous.
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Quoting stormno:
claudette is do south of applichicola fla now so her next landfall point would be pensecola or mobile if she continues on a nw heading...this will allow her at least another 8 hours over the warm waters of the gom...claudette definitely becomes a cat 1 hurricane before all is said and done...all intesests from la to pensecola should monitor this storm do to rapid intensification happeneing..Stormno


you sure? it looks like it might just o straight into panama/Apalachicola area
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Quoting Stoopid1:
Surface winds around 50mph in Claudette right now, hopefully recon hangs around for a while to see what happens.


Multiple readings too.
Member Since: October 28, 2006 Posts: 57 Comments: 30690
Us landfall is not as likely as a recurve out to sea, but the evolution of the trough will be interesting.
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guys its too soon too say where bill is going bil may or may not go out too sea like mode runs says
Member Since: May 21, 2006 Posts: 5091 Comments: 115436
Bill isn't going out to sea anytime soon until high pressure breaks down. WNW/W for today and tomorrow.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
I promise that if you had been on a fishing boat off of Key West yesterday at this time, you would've had no doubt that a tropical system was developing right above you.

It's both an awe-inspiring and chilling sight.
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What is the mess south of Cuba on the item that Drak posted?
Member Since: November 15, 2005 Posts: 16 Comments: 4189
I'm gonna go with a direct Bermuda hit no less than a glancing blow/brush. JMHO but U.S. is clear and Bermuda should watch and give their attention to Bill.
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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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