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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Any scenarios for Bill if he slows down or speeds up?
Member Since: Posts: Comments:
Quoting jipmg:
Bill is speeding up, good thing or bad thing?


bad
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting jipmg:
Bill is speeding up, good thing or bad thing?
Bad, might not curve because the high is expected to build more westward and the trough should weaken, so right now Florida still needs to watch this.
1522. Drakoen
Center is due south of Apalachicola
Member Since: October 28, 2006 Posts: 57 Comments: 30490
The COC of Claudette isn't nearly as well defined as it was a few hours ago
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Quoting KEHCharleston:
Per TWC

Evacuations ordered for Alligator Point


Evacuations! Are you serious? If you have to evacuate for a tiny weak TS then that place shouldn't be inhabited.
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1519. Patrap
Panama City to Destin fixin to Get a Good Squall,feeder..

Id beware those near the Beach as theres some rotation in them Boys.


Member Since: July 3, 2005 Posts: 424 Comments: 128275
1518. BA
dumb question, can someone tell me how to zoom out on wunderground radar? the radio buttons at the top don't seem to make a diff. maybe they don't work on mac?
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1517. code1
Quoting icepilot:


Don't bother with vid - the camera prob wouldn't survive


Ahh, let him take camera and have a coffin waiting on him as well. How old is this child?
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Shear is increasing from the north for claud she is forecasted to slow down is she not??
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Ike do you think Claudette has stalled
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1514. Michfan
That blowup of convection to the south of the center is not a relocation.
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1513. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 171 Comments: 53831
1512. jipmg
Bill is speeding up, good thing or bad thing?
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MississippiWx, you can see its just about stalled. Seen it happen several times the past few years with the WU radar you all look at. This looks too familiar.
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Quoting canesrule1:
Lots of wow factor with Bill:



Claudette really strengthening:





i think bill now have wind of 70-80mph what you think
Member Since: May 21, 2006 Posts: 5091 Comments: 115088
Quoting serialteg:


there is yes

still waiting for the report on the LLC spot
ANA.35kts-1005mb-149N-578W.100pc.jpg | From the Navy Site
Member Since: October 9, 2008 Posts: 0 Comments: 8373
look at the radar. a much broader center has formed and taken over to the south. However theres so much dry air in it i dont think it will strengthen. Does appear to be slowing down though.

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Quoting alpha992000:
SerialTeg: I'm in the Rio Piedras area.





hey alpha, did u just add me to your msn?
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Tyndall AFB Tower C (N4), FL (sgof1)

Air Temperature: 76° F / 24° C
Humidity: 94
Wind direction (W Dir): SE (125 - 134 Degrees)
Wind Speed (W Spd): 39.0 kts (44.9 mph / 72.2 km/h)
Wind Gust (W Spd): 43.0 kts (49.5 mph / 79.6 km/h)
Atmospheric Pressure (AP): 29.95 in / 1014 hPa

Pressure Tendency (PT): -0.06 in / -2.2 hPa
Steady or increasing, then decreasing; or decreasing, then decreasing more rapidly


Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Funkadelic:
Here, take a look at this:
http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

You can clearly see that Ana is well north of the forcast point... Why did they not change the track at 2:00pm??


I am 99% sure that they only change the movement direction and location at the 2 and 8 advisories. They only move the track at the 5s and 11s.
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1504. IKE
Quoting Patrap:
Claudette CoC now Sw of Apalachicola




First round of rain moving in....
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Per TWC

Evacuations ordered for Alligator Point
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Quoting FLHurricaneChaser:


Hehe perhaps. I plan on being the first person to be walking around outside in a Cat 5. I'll videotape it too.


Don't bother with vid - the camera prob wouldn't survive
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1501. Patrap
Claudette CoC now Sw of Apalachicola


Member Since: July 3, 2005 Posts: 424 Comments: 128275
Quoting WaterWitch11:
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.


OMG, I live in Southern California and have been so glued to the Atlantic storms that I didn't realize we had fires burning!
Member Since: July 15, 2005 Posts: 3 Comments: 1267
1499. IKE
Claudette looks like it's had a COC relocation SW by a few miles of where she was at.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Patrap:
Claudette may reach Cindy Of 2005,July Size and greater



That storm made me angry. The center was supposed to come across BR, and since it was a weaker storm, I figured it would be fun to watch. Turns out it had other plans. haha
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Quoting jipmg:


Is there a hunter in ANA right now? Because based on satellite ANA is far north of 14.9


there is yes

still waiting for the report on the LLC spot
Member Since: August 22, 2006 Posts: 2 Comments: 1983
Just had our first feeder band here in Tally. Hubby had to run out and put his stuff up REAL fast. (I warned him it was about to pour...) Big gust of wind when it came through.
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Lots of wow factor with Bill:



Claudette really strengthening:


1494. 996tt
Quoting Drakoen:


The center is .1 N and .1W of the last vortex message.


They did jog the center due south so must have reformed.
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1493. Drakoen
Quoting MississippiWx:


What satellite loops are you looking at to get this idea? The center is almost due south of Apalachicola and that is very evident on radar. The big blow up of convection to the south on IR loops is just in the moisture influx.


Agree
Member Since: October 28, 2006 Posts: 57 Comments: 30490
Quoting FloridaTigers:
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.


it would take more than claudette to cool those waters.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting tennisgirl08:


I think the NHC has picked up on this. Let's just wait and see what they say. I am not trying to wishcast or anything, it just seems very obvious on satellite loops.


What satellite loops are you looking at to get this idea? The center is almost due south of Apalachicola and that is very evident on radar. The big blow up of convection to the south on IR loops is just in the moisture influx.
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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.

Too shallow where she is at
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1488. Patrap
Claudette may reach Cindy Of 2005,July Size and greater

Member Since: July 3, 2005 Posts: 424 Comments: 128275
So Claudette is officially not moving?
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1486. 996tt
Seriatag:

Going back later. Got tired of catching small waves on long board after 3 hours. Fun but I am getting old . . . and saving energy hopefully for some overhead stuff.
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Quoting stormwatcherCI:
Might be a life changing experience but could also be a life ending experience.


Hehe perhaps. I plan on being the first person to be walking around outside in a Cat 5. I'll videotape it too.
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Quoting JRRP:


Interesting, the SHIPS takes Ana to 70 mph in 120 hrs.
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1482. IKE
COC looks SSE of Panama City,FL.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Drakoen:


The center is .1 N and .1W of the last vortex message.


I think the NHC has picked up on this. Let's just wait and see what they say. I am not trying to wishcast or anything, it just seems very obvious on satellite loops.
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1480. jipmg
Quoting JRRP:


Is there a hunter in ANA right now? Because based on satellite ANA is far north of 14.9
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1479. code1
Keep safe Ike and others in the panhandle. Just spoke with daughter in Destin. She said they just had a little 5 minute rain, but had been pretty most of the day. Little to no wind as yet. Sure wish I was home rather than in TX now. Love to watch the clouds as they come in. Happy we are not dealing with a monster storm.
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1478. bcn
For my non expert eyes, 25N-70W is near to interfer Claudette, and will do.

Link
Member Since: August 20, 2008 Posts: 0 Comments: 62
Quoting 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*


I'm with you.

I live in New England, and learned about the Hurricane of 1938 as a kid.

Nobody thinks we can get hit up here, but we do.

I wouldn't say that Bill is making me nervous, but I'm definitely keeping an eye on him.
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Quoting Michfan:


I do not see a centrer in that... not even close to exposed.
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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: 1983

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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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