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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2225. chevycanes
2:45 AM GMT on August 17, 2009

looks along 60 west. you can see the weakness. and there is one around 40 west.

Member Since: August 6, 2007 Posts: 0 Comments: 693
2224. Cavin Rawlins
12:01 AM GMT on August 17, 2009
Ana is now moving through, and she still got somthing with her. Gusty winds and heavy rain here.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2223. flsky
11:15 PM GMT on August 16, 2009
Quoting charlottefl:
I'm just south of the Cape we just got a pretty nasty Thunderstorm here...


South of which cape?
Member Since: October 24, 2006 Posts: 0 Comments: 1910
2222. Dakster
11:13 PM GMT on August 16, 2009
Member Since: March 10, 2006 Posts: 0 Comments: 10034
2221. Dakster
11:12 PM GMT on August 16, 2009
Quoting Babsjohnson:


Big storms don't turn.


Didn't Floyd turn just before hitting Florida?
Member Since: March 10, 2006 Posts: 0 Comments: 10034
2220. Babsjohnson
10:23 PM GMT on August 16, 2009
Quoting PanamaBeach1:
Panama City Beach, directly on the beach.. its getting windy here


It may go west of you.
Quoting tropicaltank:
If I recall did you not state that the cloudiness near key west was pathetic,yesterday. We all need to understand that these systems are unpredictable.That this is an in exact science

That is just not right. Have a little langitude.
Member Since: September 1, 2007 Posts: 3 Comments: 138
2219. Babsjohnson
10:15 PM GMT on August 16, 2009
Quoting 92Andrew:
Bill is getting huge. If not already, it should be a hurricane within the next 12 hours. I wonder if it will rival the size of Floyd during a time when that storm was being forecast to hit florida.


Big storms don't turn.
Member Since: September 1, 2007 Posts: 3 Comments: 138
2218. 92Andrew
9:54 PM GMT on August 16, 2009
Bill is getting huge. If not already, it should be a hurricane within the next 12 hours. I wonder if it will rival the size of Floyd during a time when that storm was being forecast to hit florida.
Member Since: July 27, 2009 Posts: 0 Comments: 96
2217. GatorWX
9:20 PM GMT on August 16, 2009
Ok, Claudy is not looking nearly as good now, but she still has time. Moisture just can't seem to work its way north and west around the circulation. We will see however.
banding near the center has diminished quite a bit. Tonight could be a thriller for her, much like it was last night if she's still far enough offshore.
Member Since: January 1, 2008 Posts: 0 Comments: 2673
2216. PanamaBeach1
9:17 PM GMT on August 16, 2009
Panama City Beach, directly on the beach.. its getting windy here
Member Since: August 26, 2006 Posts: 0 Comments: 61
2215. mossyhead
9:16 PM GMT on August 16, 2009
patrap, the post 2188 was very informative. it says more than a lot of words. looking at the ulls, fronts, dry air and the tropical systems. very impressive.seeing bill pushing the dry air. the ull just east of the bahamas, another one nw of bill, the high building north of claudette. thanks.
Member Since: July 7, 2008 Posts: 0 Comments: 473
2214. lopaka001
9:16 PM GMT on August 16, 2009
Bill is a nice looking system now..

Member Since: February 19, 2007 Posts: 0 Comments: 239
2213. icepilot
9:15 PM GMT on August 16, 2009
Quoting dcoaster:
What's really odd to me is that by taking the coordinates from NHC at 11AM and 5PM, converting them to statute miles, and dividing the time between advisories, I am getting roughly 19-20mph. Am I missing something?

12.1N 38.4W and 12.8N 40.0W



What are you using for the lenght of a degree of Long.?
Please remember that the distances between to longitude lines varies greatly by latitude. @ 45 deg LAT, each deg of Long is ~ 48.99 Stat Miles. So every .1 deg of long at that LAT is 4.9 Stat Miles. and if LAT changes then the lenght of Long changes

Here is a simple calculator.
Lenght calc for Lat & Long
Member Since: July 9, 2005 Posts: 0 Comments: 387
2211. HIEXPRESS
9:13 PM GMT on August 16, 2009
Y'all missed the
NEW BLOG
Member Since: October 13, 2005 Posts: 4 Comments: 2156
2210. pcola57
9:11 PM GMT on August 16, 2009
Quoting pcolasky:


I am very close to the airport in P'cola
Westside/Myrtle Grove here
Member Since: August 13, 2009 Posts: 13 Comments: 6770
2209. TXEER
9:07 PM GMT on August 16, 2009
Quoting mossyhead:
i may get banned from here for saying this, but GOD created the world, not so-called mother earth.


I agree but I'm its not a bother to me when someone uses that statement. Its a general catch phrase and I do not find it offensive.
Member Since: August 26, 2008 Posts: 0 Comments: 107
2208. Skylink
9:06 PM GMT on August 16, 2009
Ok, Ive put up some more web cam and live streams on the site for Claudette. Click Below

Link
Member Since: January 23, 2003 Posts: 0 Comments: 36
2207. winter123
9:05 PM GMT on August 16, 2009

(thanks patrap)

See the dry line that is moving south over Alibama? i that will stop it from coming ashore and it will move west.
Member Since: July 29, 2006 Posts: 28 Comments: 1776
2206. hurcaloid
9:05 PM GMT on August 16, 2009
In Shalimar (near Fort Walton Beach intercoastal) all we've received has been a minor band with light rain and wind. The sun's out now...
2204. RadarRich
9:02 PM GMT on August 16, 2009


Batten down the hatches, might get a little wet and windy in here
Member Since: June 28, 2007 Posts: 0 Comments: 406
2202. bluehaze27
9:02 PM GMT on August 16, 2009
Quoting CaneWarning:


The NHC is also putting alot of confidence in the models. They've shifted their track because of them. Hey, if the experts are doing it, why shouldn't I? :)


There is what is forecasted, and then there is what is. We shall see. I seem to remember Andrew was forecasted to catch a trough. Forecasting is still a swag---scientific wild ass guess, and forecasts are busted all the time.
Member Since: March 26, 2007 Posts: 0 Comments: 813
2201. southfla
9:01 PM GMT on August 16, 2009
The potential for the dry air impacting TS Bill looks higher today than yesterday, but Bill looks pretty good considering. Thoughts ?

Yesterday


Today
Member Since: May 19, 2009 Posts: 0 Comments: 249
2200. mossyhead
9:01 PM GMT on August 16, 2009
Quoting Dakster:


Trade winds.. Climatology and of course, Mother Nature has setup the Earth to do this during this time of year.

i may get banned from here for saying this, but GOD created the world, not so-called mother earth.
Member Since: July 7, 2008 Posts: 0 Comments: 473
2199. TexasHurricane
9:01 PM GMT on August 16, 2009
Looks like another good wave fixing to come off of Africa..

Member Since: July 2, 2009 Posts: 0 Comments: 2811
2198. HurricaneKyle
9:01 PM GMT on August 16, 2009
Quoting P451:
12Z Runs...

GFS 168HR




CMC 144 HR




Ouch.. if that occurs.. then that could cause serious damage to New York City and surround states.
Member Since: August 10, 2009 Posts: 3 Comments: 672
2195. CatastrophicDL
9:00 PM GMT on August 16, 2009
Quoting CaneWarning:


Nasty storms are forming up and down the west coast right now.

Cane, have you unplugged your electronics yet? LOL :o)
Member Since: September 3, 2007 Posts: 3 Comments: 1519
2194. CaneWarning
8:59 PM GMT on August 16, 2009
Quoting P451:
12Z Runs...

GFS 168HR




CMC 144 HR




Wow that's interesting.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
2192. washingaway
8:58 PM GMT on August 16, 2009
Quoting yonzabam:
NHC 5pm advisory says Claudette is moving at 14 mph. Seem that way to you?


No - not at all
Member Since: July 14, 2006 Posts: 0 Comments: 1144
2191. druseljic
8:58 PM GMT on August 16, 2009
Link

Looking more impressive all the time...
Member Since: August 13, 2007 Posts: 0 Comments: 655
2190. CaneWarning
8:58 PM GMT on August 16, 2009
Quoting charlottefl:
I'm just south of the Cape we just got a pretty nasty Thunderstorm here...


Nasty storms are forming up and down the west coast right now.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
2189. Derlong54
8:58 PM GMT on August 16, 2009
Member Since: August 13, 2008 Posts: 0 Comments: 17
2188. Patrap
8:58 PM GMT on August 16, 2009
Member Since: July 3, 2005 Posts: 420 Comments: 127512
2186. charlottefl
8:57 PM GMT on August 16, 2009
I'm just south of the Cape we just got a pretty nasty Thunderstorm here...
Member Since: December 18, 2006 Posts: 7 Comments: 2685
2185. tiggeriffic
8:57 PM GMT on August 16, 2009
Stormtrop was a troll last year...dont listen to her! Anything that any other expert says, she goes against it...
Member Since: September 16, 2007 Posts: 0 Comments: 3650
2184. weatherfan92
8:57 PM GMT on August 16, 2009
To be honest, I'm surprised Bill wasn't a hurricane at 5pm judging by the satellite presentation all afternoon.
2183. CatastrophicDL
8:57 PM GMT on August 16, 2009
Quoting extreme236:


She might be an open wave.

According to CIMSS, she's still got some lower level vorticity, but probably not much on the surface.
Member Since: September 3, 2007 Posts: 3 Comments: 1519
2182. jipmg
8:56 PM GMT on August 16, 2009
Quoting yonzabam:
NHC 5pm advisory says Claudette is moving at 14 mph. Seem that way to you?


hey they are saying Bill is moving at 16mph, doesnt look like it to me, and Claudette seems alot slower than 14 mph.. but hey its there word
2181. hurristat
8:56 PM GMT on August 16, 2009
Interesting. The NHC has Ana regaining TS strength before hitting Hispanola, and then it has her paralleling Cuba and going into the GoM.
Member Since: October 15, 2008 Posts: 11 Comments: 2305
2180. PalmBeachWeather
8:56 PM GMT on August 16, 2009
Not you StormW,.......I respect what you say
Member Since: October 3, 2008 Posts: 0 Comments: 5813
2179. tropicaltank
8:56 PM GMT on August 16, 2009
Quoting BrockBerlin:
Finally the pathetic storm Ana should die, but wait where's Stormtrop to say that Ana will regenerate become a Cat.5 hurricane and slam into New orleans?
If I recall did you not state that the cloudiness near key west was pathetic,yesterday. We all need to understand that these systems are unpredictable.That this is an in exact science
Member Since: June 27, 2009 Posts: 0 Comments: 242
2177. yonzabam
8:55 PM GMT on August 16, 2009
NHC 5pm advisory says Claudette is moving at 14 mph. Seem that way to you?
Member Since: July 20, 2008 Posts: 0 Comments: 2892
2176. Tazmanian
8:55 PM GMT on August 16, 2009
Quoting extreme236:


She might be an open wave.



i think it been a open wave from time of this AM
Member Since: May 21, 2006 Posts: 5091 Comments: 114696
2175. CaneWarning
8:56 PM GMT on August 16, 2009
Quoting bluewaterblues:


You sure do put a lot of confidence in what the models are saying with this thing several days out...I am guessing that you will change your tune when the ridge builds back in and Bill resumes a more westaward track.


The NHC is also putting alot of confidence in the models. They've shifted their track because of them. Hey, if the experts are doing it, why shouldn't I? :)
Member Since: April 26, 2009 Posts: 3 Comments: 3667

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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.