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 stormno:
SZGRN IM AFRAID IT COULD GET A LOT WORSE YOU NEEDS TO KEEP A HEADS UP IN MISSISSIPI BECAUSE IT LOOKS NOW THIS WILLGET A LOT CLOSER TO YOU GUYS AS IT CONTINUES TO PARALELL THE COAST...I THINK ITS POSSIBLE FOR CLAUDETTE TO SLOW DOWN AND EVEN BECOME STATIONARY..THIS REALLY BEARS WATCHING SO STAY ON YOUR TOES...Stormno


Thanks.. definately watching!
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I not too sure Bill going to move that far north, it went WNW for a bit this morning , now it seems to be headed back westward imo.
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Quoting Tazmanian:
dos any one think ANNA is now a open wave???
me
Quoting fire635:
I wouldnt be surprised if TD4 gets reclassified as a strong TS on the next update. She looks VERY impressive on radar
not strong but 45 mph is possible.
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Ana is tracking way off her forecast points.
Member Since: October 28, 2006 Posts: 57 Comments: 29910
Quoting hurricane23:
As noted by blake, bill continues to display a spectacular curved band pattern on visible imagery.You can see it here on this large 1km image.

Bermuda might want to keep an eye out on bill.


Everyone should keep an eye on Bill. Nobody knows where it is exactly going to go.
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Drak called a fish last year...but it also seemed like every storm was a fish as well...I remember Ike was a fish...Gustav was a fish...Models will adjust as the storms continue and strengthen or weaken...but they will adjust and the curve to sea may be a curve to SC in a day or 2
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If HH find a stronger TD 4 the NHC will immediately issue a special update.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
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I wouldnt be surprised if TD4 gets reclassified as a strong TS on the next update. She looks VERY impressive on radar
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dos any one think ANNA is now a open wave???
Member Since: May 21, 2006 Posts: 5091 Comments: 114756
Who blew up my Atlantic? [jk] In a more serious tone, I have been occupied for the last day [unable to post] and I truly was not expecting TD2 to rise again. Looks like it's still having its issues with dry air, even as the shear drops. However, while most of the models have it dying out, the NHC has it going over Hispanola and surviving that and making it to the gulf as a tropical depression.
Also, just checking the 11 o'clock update, looks like Bill just jumped by about 15 mph to 60 mph. Fortunately, with the 11am update, it looks as though this will curve out to sea. While I hope the NHC track is true, it passes just north of that 20N60W mark that can often be used as a guideline for whether the storm will curve out to sea or not. Furthermore, while this loose estimation is often inaccurate and does not portray the actual or future conditions of the atmosphere at that point, a category 3 (as the NHC forecasts) storm of this size could still be a huge problem for the Bermuda and/or the Lesser Antilles.
Regarding TD4- I have a feeling that it's not going to be christened Claudette. It hasn't strengthened since the 5am update, and while it may strengthen over the very heat-laden waters of the GoM, it's running out of room and does not have the space needed to strengthen quickly into Claudette. I know everyone will say, Humberto, Humberto, remember Humberto? I do remember Humberto, but I just have a feeling that this will be very similar to TD10 of 2007; that one had the potential to become Jerry, but did not. I'm giving this one a 40% chance of being named. Disclaimer, however, my predictions are not fact, and anyone on the panhandle or any affected area should be preparing for the worst-case scenario.

Also, on a lesser but related note, looks like Stormtop (in his newest reincarnation Stormno), the blind squirrel, has finally found his acorn. kudos.
Member Since: October 15, 2008 Posts: 11 Comments: 2305
Quoting canesrule1:
http://tropicalatlantic.com/recon/


Thanks...
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When does the new GFS run come out?
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CHIPS has fallen in step with the others further (except for one ensemble member).


1. Would it not be interesting if the little bump in intensity at 36 hours can to fruition?
2. And just what would be the cause of that? Dry air entrainment?
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04L is SSE of Apalachicola
Member Since: October 28, 2006 Posts: 57 Comments: 29910
Quoting extreme236:
Bill looks to be getting rather close to hurricane status.
hurricane bill at 5 for sure
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Quoting yonzabam:


And I can't figure out why Bill is expected to follow a much more northerly track, instead of following Ana westwards.


read

the

nhc

discussions on bill :)
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Quoting stormno:
STORMTOP SPECIAL WEATHER STATEMENT ON TROPICAL STORM CLAUDETTE..CLAUDETTE CONTINUES TO HOLD HER OWN AND SHE STILL HAS ABOUT 100 MILES TO GO BEFORE SHE MOVES INTO THE FLA PANHADLE..PEOPE I WOULD NOT LET YOUR GUARD DOWN OVER MOBILE..THERE ARE SOME INDICATIONS CLAUDETTE BEFORE COMING ONSHORE MAY MOVE ON A MORE NW COURSE AND AFFECT THE MOBILE AREA WITH TORRENTIAL RAINS AND WINDS GETTING UP TO 65MPH..ITS A GOOD THING CLAUDETTE TOOK THE NNW COURSE AND DIDNT TAKE THE NW COURSE ARE WE COULD HAVE BEEN DEALING WITH A CAT 2 HURRICANE..THERE ARE ALSO INDICATIONS DUE TO THE TROUGH ABOVE CLAUDETTE SHE WILL START TO SLOW DOWN SO ALL INTERESTS IN THE MOBILE AREA SHOULD DEFINTELY MONITOR THE WEATHER ADVISORIES.LOCALLY HEAVY RAIND COULD BE UP TO 6 INCHES TO THE RIGHT OF THE CENTER...ILL BE BACK AT 2PM WITH SOME MORE INFO ON TROPICAL STORM CLAUDETTE...


-spits out morning coffee- is this WS too? Awesome grammar and spelling there.. LMAO

I've been watching TD4 for a few days, yesterday here in Homestead, Fl it was raining like crazy. Hope everyone stays safe up north. It's incredible how awesome mother nature could be. Still keeping an eye out for all 3 systems, you never know what can happen till it does.
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Quoting Dakster:
Anyone still have the link to follow the Hhunters in google earth?

That was pretty cool last year.
http://tropicalatlantic.com/recon/
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Bill looks to be getting rather close to hurricane status.
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Stormno..
..last night you warned about TS in Gulf this AM.. you called that correcty... I am listening and watching here in MS
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Quoting watchingnva:


thats cool dude, ive been guilty of posting way too much in the past...lol...both planes are still way far way from their prospective coc...so...give them at least 20-30 min to get closer...
alright. LOL
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Anyone still have the link to follow the Hhunters in google earth?

That was pretty cool last year.
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Quoting TheDawnAwakening:
TD4 now looks like Claudette, on both satellite and radar imagery. It also looks to have moved westward a little.

Its running into that ridge to its north.
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Quoting Prgal:

I think we should pay close attention to both storms. These tracks will go back and forth and conditions can change quickly. We should all be ready for a storm during hurricane season with food and water stored (you know that with a breeze the power goes out lol). So in my opinion, lets just keep an eye and be ready just in case. Tomorrow morning we should have a better idea of what to expect.


we should all get together and party imo...

yesterday i grabbed a 24pack Medalla crate and grandma said no :(
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TD4 now looks like Claudette, on both satellite and radar imagery. It also looks to have moved westward a little.
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447. IKE
Looks like TD4 is west of the buoy at 28.5N and 84.5W. Winds have shifted to the south...Link

"Wind Direction (WDIR): S ( 180 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 21.4 kts
5-day plot - Wind Gust Wind Gust (GST): 25.3 kts
5-day plot - Wave Height Wave Height (WVHT): 5.2 ft
5-day plot - Dominant Wave Period Dominant Wave Period (DPD): 8 sec
5-day plot - Average Period Average Period (APD): 5.8 sec
5-day plot - Mean Wave Direction Mean Wave Direction (MWD): ESE ( 122 deg true )
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.96 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): +0.03 in ( Rising )
5-day plot - Air Temperature Air Temperature (ATMP): 80.1 °F
5-day plot - Water Temperature Water Temperature (WTMP): 85.8 °F
5-day plot - Dew Point Dew Point (DEWP): 74.8 °F
5-day plot - Heat Index Heat Index (HEAT): 84.9 °F"
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting canesrule1:
sorry, I messed up something, i have taken it off.


thats cool dude, ive been guilty of posting way too much in the past...lol...both planes are still way far way from their prospective coc...so...give them at least 20-30 min to get closer...
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Quoting WPBHurricane05:
I can't figure out how Ana will end up over Hispaniola.

If she degenerates into an open wave (which is a possibility) she would end up in the EPAC.


And I can't figure out why Bill is expected to follow a much more northerly track, instead of following Ana westwards.
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Low north of the DR is an upper level low.
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Quoting rxse7en:
Thank you! Didn't realize we were in such good shape this year.

We are back in the yellow up here. My main interest here is the effects of the tropical systems on our rainfall. If we are in the path, we get a good soaking. If we are not, the system typically will draw in moisture from such a large area that we get a long dry spell.
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TD4 beginning to show impressive wrapping and banding features.
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The NHC has it curving to early, i think a curve around the Bahamas is plausible.



Latest Satellite with Bill:



Moving WNW to escape the ITCZ:



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440. Prgal
Quoting canesrule1:
Link

Ok, I went to that page and it says "SFMR 87 knots"????
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If that dry air keeps Bill down a bit in strength, couldn't that allow it to track a bit more westerly before making the poleward turn? I agree likely a fish storm, but still not a guarantee. Still worth watching the next day or so. Might want this one to strengthen so it heads north to nowhere.
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Best wishes to all my friends and family along the Panhandle of Florida in the coming days!

Fare well!
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I can't figure out how Ana will end up over Hispaniola.

If she degenerates into an open wave (which is a possibility) she would end up in the EPAC.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting canesrule1:
me too, Something like an Andrew 92' track.


What happened to posting the raw data? Those formatted posts are huge!

SO, now that we have Ana, Bill, and Claudette out of the way. Where does everyone think Danny going?
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Link

what's the name for the large low pressure blob due North of D.R. in the vid shot above?
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Quoting watchingnva:


we dont need the whole page pasted brother...if you see an interesting pressure or wind speed...by all means put it up...but not everything...
sorry, I messed up something, i have taken it off.
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Quoting hurricane23:
As noted by blake, bill continues to display a spectacular curved band pattern on visible imagery.You can see it here on this large 1km image.

Bermuda might want to keep an eye out on bill.
NARCHER WILL BE FILMIMG BERMUDA
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Quoting sporteguy03:


????


You should be used to his personality by now lol
Member Since: October 28, 2006 Posts: 57 Comments: 29910
Link
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429. Prgal
Quoting serialteg:


not me...

I dont either.
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Quoting serialteg:


not me...
Link
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Quoting hurricane23:
As noted by blake, bill continues to display a spectacular curved band pattern on visible imagery.You can see it here on this large 1km image.

Bermuda might want to keep an eye out on bill.


The cyclone is still being inhibited by dry air to it's west.
Member Since: October 28, 2006 Posts: 57 Comments: 29910
Quoting canesrule1:
ANA

Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor


we dont need the whole page pasted brother...if you see an interesting pressure or wind speed...by all means put it up...but not everything...
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Quoting hurricane23:
Thankfully its all bark no bite so far this season. A few weak td's which could be rain producers and mighty bill should stay out to sea.

Adrian


????
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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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