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 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!

Radio stations are notorious for ignoring anything not in the immediate local area. Since the cone doesn't even quite reach Pensacola at this time I'm not surprised radio station doesn't mention it.
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Guys - it looks like we may have Hurricane Bill - he is certainly starting to fight the dry air and is slowly developing an eye.
Member Since: April 27, 2008 Posts: 29 Comments: 2097
1023. Drakoen
Quoting IpswichWeatherCenter:


While I usually trust you 99% Drakoen - any chance of a source?


Don't have the link
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1022. Dakster
Canesrule1 - I link the google earth link... I was following the recon mission as well.
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Quoting srada:


this is still a little too close for comfort..werent the previous model runs forecasting it to recurve sooner? It looks like it getting closer and closer for a US hit


Exactly the US is not of the question as yet. Like i said before the Carolinas up should be keen on Bill... Florida and Gulf Coast keen on Ana.... and Panhandle on Claudette
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Drak, mail
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1019. Patrap
Quoting Skyepony:
By recon Claudette is embeded on an 1018mb high. She's dropped 6-7mb since this time yesterday, while the high strengthened a few. 1008mb Tropical Storm...well ya'll know I'm not suprised..



Nope..no surprise here either Skyepony,..you n
and I were on this one early thursday if recall serves me well.
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That is why you really can't give high confidence to the models until 72 hours before an expected hit.
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Quoting TexasHurricane:
So Claudette is here...She is looking good might I add. Who would have thought we would have something form in the GOM that quick. But then, I quess it shouldn't be a surprise since the GOM waters are HOT!!

So the models for Bill are still looking to be a fish storm. Who is not agreeing with that? What are your thoughts?


i was crying fish this morning on bill ... no way to know for sure just keep tracking. latest satellite i saw had it jog westward change from west-northwestward but thats all it is ATM a jog
Member Since: August 22, 2006 Posts: 2 Comments: 1975
coastal station measuring some of the winds, so far.

Member Since: August 16, 2007 Posts: 6 Comments: 12461
1015. jipmg
Quoting tropicaltank:
Isn't it unusual for a trough to dig down this far in mid-august?It has been said that the computer models frequently over estimate the rapidity in which the troughs proceed eastward.


We have had troughs dig in to the south east commonly throughout the summer, so it looks like it might happen
Recon has found 50 knot winds at the surface. with claudette
right so with that said sky with the high strengthened no way will bill get pulled out too sea
Member Since: May 21, 2006 Posts: 5089 Comments: 114061
1012. Grothar
Quoting TexasHurricane:
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?
I don't believe it is way off, however, I am of the opinion that there would appear to be many factors coming into play which could alter the path. I received some insightful information from 456, Drak and others that would appear to be consistant with a revision of both systems in the forthcoming days.
Member Since: July 17, 2009 Posts: 63 Comments: 23726
1011. Dakster
StormWW - Do you believe the new Bill forecast track is accurate?
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1010. Michfan
Quoting IpswichWeatherCenter:


While I usually trust you 99% Drakoen - any chance of a source?


Get google earth and watch the recon.
Member Since: September 7, 2007 Posts: 0 Comments: 1617
Quoting LightningCharmer:
Was in the Keys yesterday, and even though I think I was the first to report on this blog west shifting winds both, firsthand, and copy and pasting Sand Key Buoy's readings, you were the only one acknowledging me. Almost every other blogger (there were a few exceptions) were concentrating on Ana and soon to be Bill.


It's actually understandable. Many people are inclined to CV developers. Lots of lead time and there's plenty of crow to go around with those.

Backyard developers, like Claudette, aren't glamorous enough for most.

Still, if they had a chance to watch a depression form right above their standing position on the surface of the Earth, that would change, I truly believe that.

But if you have never seen one spin up from scratch, you don't know, so how can you expect people to appreciate it.
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I've been coming here for nearly 5 years and it always amazes me that the same people who said "ignore the models" yesterday are the same ones that say "believe the models" today. ugh. and dont get me started on the "ignore the center line/believe the center line" folks
Member Since: September 18, 2005 Posts: 0 Comments: 117
I've been watching Claudette most of the morning. On radar, it doesn't look like she is go as far west as they predicted. Looks more like Appalachicola with the big bend getting most of the storms.
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Well, looks like I was WAY off with my prediction that Claudette wouldn't become Claudette. Oops.
Member Since: October 15, 2008 Posts: 11 Comments: 2305
Quoting extreme236:


Unless this strengthens more than expected.


Yes
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1003. srada
Quoting extreme236:


Link


this is still a little too close for comfort..werent the previous model runs forecasting it to recurve sooner? It looks like it getting closer and closer for a US hit
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Quoting Drakoen:


The maximum surface winds found so far has been 45knots


While I usually trust you 99% Drakoen - any chance of a source?
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Quoting CaneWarning:


It's a very small circulation. Our local met said even where this makes landfall there should only be about an hour of bad weather. Other than that just rain.


Unless this strengthens more than expected.
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1000. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Quoting StormW:
Good afternoon!
Good afternoon. Hope all is well with you and your family.
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Quoting szqrn1:


Even so...no mention of it at all? We are only 30 min drive to Mobile.


It's a very small circulation. Our local met said even where this makes landfall there should only be about an hour of bad weather. Other than that just rain.
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Quoting Tazmanian:



wish storm?


Claudette
Member Since: August 22, 2008 Posts: 12 Comments: 6010
Quoting Drakoen:


The maximum surface winds found so far has been 45knots
yup
Quoting Skyepony:
By recon Claudette is embeded on an 1018mb high. She's dropped 6-7mb since this time yesterday, while the high strengthened a few. 1008mb Tropical Storm...well ya'll know I'm not suprised..


Yep - so basically Claudette would normally be about 999mb by now.

Stupid High-Pressure.
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Well, since I'm out of position to document landfalling Claudette this evening, I might as well watch TW win his 15th major.

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Quoting jipmg:
looks like the convection that blew over ANA's center has caused it to shift WNW, which makes it more of a threat to the bahamas than it wa sbefore, I see models shifting north.


The HWRF shifted north. The BAMS would take it into the Bahamas.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
What is going on with the ridge to the north of Claudette?
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Quoting floridastorm:
Does anyone think that there is a chance that Ana could to a northern path and possibly affect the east coast of Florida?
Thanks


That is what alot of the models are thinking, although some are saying it could affect the bahamas and the East coast of GA and the carolinas.
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Quoting CycloneOz:
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.
Was in the Keys yesterday, and even though I think I was the first to report on this blog west shifting winds both, firsthand, and copy and pasting Sand Key Buoy's readings, you were the only one acknowledging me. Almost every other blogger (there were a few exceptions) were concentrating on Ana and soon to be Bill.
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Quoting CaneWarning:


That makes sense. It should'nt be anywhere near that location.


Even so...no mention of it at all? We are only 30 min drive to Mobile.
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Quoting willdunc79:
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.


Fl is more than likely safe, but from the Carolinas up the Eastern seaboard should be vary. Bastardi from accuweather said so.... the models first had Bill hitting New Orleans now have Bill going to New Fouldland. In the next 3 -5 days we will know if Bermuda would be the only ones afffected by Bill or not. Hope they dont get a direct hit because that would totally devastate them. If you live in the South coast Ana should be your interest although she is struggling now.

Here is the link
http://www.accuweather.com/video-on-demand.asp?video=24528283001&title=How%20%27bout%20that%20%20Gu lf%20%20development!%20Ana%20and%20Bill%20update
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Quoting CaneWarning:
Bill is more and more likely to recurve. U.S. landfall is very unlikely.
Isn't it unusual for a trough to dig down this far in mid-august?It has been said that the computer models frequently over estimate the rapidity in which the troughs proceed eastward.
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Quoting IpswichWeatherCenter:


I've got 43.1 knots (~ 49.5 mph)
Tropical Storm
i saw that too
Quoting IpswichWeatherCenter:


I've got 43.1 knots (~ 49.5 mph)
Tropical Storm


The maximum surface winds found so far has been 45knots
Member Since: October 28, 2006 Posts: 57 Comments: 29714
984. jpsb
Quoting CycloneOz:


I count you as one of the few who did. Chill...
Ok, sorry, and thanks. I thought it would go further west. The LLC formed further north then I thought I would.
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Buoy updated.

Conditions at SGOF1 as of
(1:00 pm EDT)
1700 GMT on 08/16/2009:
Unit of Measure: Time Zone:

Click on the graph icon in the table below to see a time series plot of the last five days of that observation.
5-day plot - Wind Direction Wind Direction (WDIR): SE ( 130 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 37 kts
5-day plot - Wind Gust Wind Gust (GST): 40 kts
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.98 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.04 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 77.0 °F
5-day plot - Water Temperature Water Temperature (WTMP): 85.3 °F
5-day plot - Dew Point Dew Point (DEWP): 74.5 °F
5-day plot - Wind Speed, Wind Gust and Atmospheric Pressure Combined plot of Wind Speed, Gust, and Air Pressure
Member Since: September 7, 2007 Posts: 0 Comments: 1617
982. jipmg
looks like the convection that blew over ANA's center has caused it to shift WNW, which makes it more of a threat to the bahamas than it wa sbefore, I see models shifting north.
http://www.ndbc.noaa.gov/station_page.php?station=apcf1
Center due south of this buoy per 1:06 EDT.
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Quoting srada:


Hi

Can you post the link?


Link
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Quoting Tazmanian:



wish storm?


Hahah, do you really think that Ana is even close to being capable of that?

Its Claudette.
Member Since: April 27, 2008 Posts: 29 Comments: 2097
Quoting Alockwr21:


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?


Poof.
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977. Skyepony (Mod)
By recon Claudette is embeded on an 1018mb high. She's dropped 6-7mb since this time yesterday, while the high strengthened a few. 1008mb Tropical Storm...well ya'll know I'm not suprised..
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Quoting Drakoen:


Multiple readings too.


Yup, so it seems reliable. Recon looks to be making a center run soon, so we'll see what's happening with the COC. Runs into the NE quadrant again from there will be interesting.
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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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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.