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 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? :)
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Ah.Na
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2172. Patrap
Claudette,RGB Image




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Quoting CaneWarning:


That's true, but at the same time, it is likely this will curve away. This is about the second day I've seen models curving it before Florida.


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 westward track.
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Quoting AllStar17:


Also note this, Taz:
THE OTHER SOLUTION...SHOWN BY THE
NOGAPS/UKMET...IS THAT THE HURRICANE BYPASSES THE FIRST BREAK AND
CONTINUES MOVING TOWARD THE WEST-NORTHWEST...EVENTUALLY TURNING
NORTHWEST AT THE END OF THE FORECAST DUE TO A LARGE MID-LATITUDE
TROUGH APPROACHING THE EASTERN UNITED STATES.




noted
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Quoting Tazmanian:
i dont see any turning with ANNA i think she is a open wave


She might be an open wave.
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So many experts.So little knowledge....It's all a repeat
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Quoting DestinJeff:


Niceville, northside of Mid-bay bridge. headed to beach house later ... want to wait for C to get in closer, but watchingthe wind for 40 moh


I am very close to the airport in P'cola
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2166. jipmg
when are the next model runs expected to be
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I wonder if a Tornado Watch will be issued soon.
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2164. TX2FL
Quoting CosmicEvents:
Large ant mounds in unusual spots precede incoming tropical cyclones. It's been (un)scientifically proven from reports here over the last 5 years.


How relevant is that to inland? We have huge ant hills this month in Dallas in my yard and neighbors too..and little pink lizards like crazy in the house.. Every night I have to pick one up and take it outside.
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i dont see any turning with ANNA i think she is a open wave
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they shifted claudette's track to the west....a bit...

THE INITIAL MOTION IS ESTIMATED AT 315/12. THE TRACK REASONING
REMAINS UNCHANGED...AS CLAUDETTE WILL CONTINUE TO MOVE
NORTHWESTWARD AROUND THE PERIPHERY OF THE SUBTROPICAL RIDGE. THE
OFFICIAL FORECAST HAS BEEN SHIFTED SLIGHTLY TO THE LEFT...TOWARD THE
MODEL CONSENSUS. ON THE FORECAST TRACK CLAUDETTE WILL MAKE LANDFALL
TONIGHT IN THE FLORIDA PANHANDLE. BEYOND THAT TIME...THE WEAKENING
CYCLONE WILL TRACK NORTHWEST PRIOR TO DISSIPATING NEAR THE
MISSISSIPPI/ALABAMA BORDER IN ABOUT 48 HOURS.
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Quoting Fl30258713:
When does the next Quikscat image show up?
.


bill 7pm
ana and claudette 8-9pm
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Quoting Tazmanian:
hmmmmon bill

THE OFFICIAL
FORECAST IS SHIFTED A LITTLE BIT TO THE RIGHT AT THE END...IN
DEFERENCE TO THE HIGHLY-SKILLED MODELS IN THE FORMER SOLUTION.


Also note this, Taz:
THE OTHER SOLUTION...SHOWN BY THE
NOGAPS/UKMET...IS THAT THE HURRICANE BYPASSES THE FIRST BREAK AND
CONTINUES MOVING TOWARD THE WEST-NORTHWEST...EVENTUALLY TURNING
NORTHWEST AT THE END OF THE FORECAST DUE TO A LARGE MID-LATITUDE
TROUGH APPROACHING THE EASTERN UNITED STATES.
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HEADS UP CAPE CORAL/PORT CHARLOTTE

Tornado Warning.
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2157. jipmg
Quoting watchingnva:


your seeing a very tall hot tower building right on top of the coc...no eye yet...maybe later tonight...


I was looking at the central atlantic satellite, not the close up, makes it look like an eye , but its really a shadow
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Quoting Tazmanian:
hmmmmon bill

THE OFFICIAL
FORECAST IS SHIFTED A LITTLE BIT TO THE RIGHT AT THE END...IN
DEFERENCE TO THE HIGHLY-SKILLED MODELS IN THE FORMER SOLUTION.


Yep Taz, Bill may visit Bermuda, but that's about it.
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Bill is going to make either a direct hit to Bermuda or brush it closely. Lower 48 states are safe from Bill as it seems now.
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Cuba waits for the surpluses of Ana Tuesday. Apparently this system will only give something of rain in the Eastern region where the precipitations have been little in July and what it goes of August. They must say in Haiti so that in Bill truth more moves away to the north.
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IMO if Bill doesn't go N or NE by 35 N, if its still heading NW, we could be talking about a Landfall in the Northeast. Anywhere from Delaware to Maine.
Member Since: August 10, 2009 Posts: 3 Comments: 672
2152. Patrap
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Quoting AllStar17:
Ana a depression. NHC track may need to be shifted even more south, even south of Hispaniola, Cuba, and Puerto Rico, which if the storm stays in tact, would not be good.

Also, I do not know if Bill will end up being a fish. It is certainly not a sure thing.


yeah, even if Ana turns back into just a wave, if she can get into the GOM then she could come back. She already has before.
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hmmmmon bill

THE OFFICIAL
FORECAST IS SHIFTED A LITTLE BIT TO THE RIGHT AT THE END...IN
DEFERENCE TO THE HIGHLY-SKILLED MODELS IN THE FORMER SOLUTION.
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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
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Ana dies again...
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2147. jdjnola
Quoting Relix:
Hey Ana is a depression =P


...again. Then a remnant low... again? Then a TS... again?
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TXEER...

Basically it is their rainy season...the more rain and big storms they get, the more that come off the coast...it also has to do with the el nino and la nina...they play how much africa gets in rain...also the trade winds... it all combines together to create hurricane season...if africa got its rain from december to say may...we would not have the hurricanes because our water temps would not support the development of such storms...
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2144. TXEER
Weather456 and Dakster...thanks for the answers and for not piling on a newbie...I appreciate it...this is a great place to learn.
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Quoting jipmg:
I see a small eye on bill via visible satellite popping out


your seeing a very tall hot tower building right on top of the coc...no eye yet...maybe later tonight...
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2142. Patrap
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Quoting Weather456:


serves her right, indecent exposure is a crime.


Hahaha!
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Mossyhead - assume that's where you are? Niceville here.
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Quoting Weather456:
Bermuda watch out



Bill might effect the Northeast with that kind of path. Maybe like Gloria.
Member Since: August 10, 2009 Posts: 3 Comments: 672
2138. jdjnola
Quoting Dakster:
Can someone please hit the nail on the head of Ana's coffin this time. She keeps coming back to life...



Everyone was waiting and anticipating her birth... now everyone is waiting and anticipating her demise.
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When does the next Quikscat image show up?
.
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Quoting iceman100:
Just got a tornado in Cape Coral. Claudette's presence felt, even though it's a ways off now.


Local news just showed a picture of Tornado over Cape Coral Fl.
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Tornado on the ground reported near Cope Coral.
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Quoting CaneWarning:
Poor Ana.


serves her right, indecent exposure is a crime.
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BILL IS MOVING TOWARD THE WEST-NORTHWEST OR 285/14. THIS GENERAL
MOTION IS EXPECTED FOR THE NEXT COUPLE OF DAYS AS A SUBTROPICAL
RIDGE SHOULD REMAIN FIRM TO THE NORTH OF THE TROPICAL CYCLONE.
THEREAFTER...A COUPLE OF EVOLUTIONS TO THE SYNOPTIC PATTERN SEEM
POSSIBLE. THE FIRST...FAVORED BY THE GFS/ECMWF/GFDL/HWRF...SHOWS A
MID-LATITUDE SHORTWAVE DIVING INTO THE SUBTROPICAL RIDGE...CAUSING
IT TO BREAK AROUND 65W. THIS LEADS TO A NORTHWEST MOTION OF BILL
IN ABOUT THREE DAYS. THE OTHER SOLUTION...SHOWN BY THE
NOGAPS/UKMET...IS THAT THE HURRICANE BYPASSES THE FIRST BREAK AND
CONTINUES MOVING TOWARD THE WEST-NORTHWEST...EVENTUALLY TURNING
NORTHWEST AT THE END OF THE FORECAST DUE TO A LARGE MID-LATITUDE
TROUGH APPROACHING THE EASTERN UNITED STATES. THE OFFICIAL
FORECAST IS SHIFTED A LITTLE BIT TO THE RIGHT AT THE END...IN
DEFERENCE TO THE HIGHLY-SKILLED MODELS IN THE FORMER SOLUTION.

Interesting discussion. Wonder if the other models might follow the NOGAPS and the UKMET.
Member Since: August 10, 2009 Posts: 3 Comments: 672
Looks like the folks on the Fla. panhandle need to bring in the garbage cans and patio furniture.
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Ana a depression. NHC track may need to be shifted even more south, even south of Hispaniola, Cuba, and Puerto Rico, which if the storm stays in tact, would not be good.

Also, I do not know if Bill will end up being a fish. It is certainly not a sure thing.
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Hitting kinda close to home:

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHWESTERN CHARLOTTE COUNTY IN FLORIDA.
NORTHWESTERN LEE COUNTY IN FLORIDA.

* UNTIL 515 PM EDT

* AT 443 PM EDT...THE PUBLIC REPORTED A TORNADO 7 MILES NORTHEAST OF
PINE ISLAND...OR 8 MILES NORTH OF CAPE CORAL...MOVING NORTHWEST AT
20 MPH.

* THE TORNADO WILL BE NEAR...
PINE ISLAND.
BOCA GRANDE.
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Quoting jipmg:


It continues W-WNW

@weather456

stop being a fishcaster


There are troughs forecast to come down. It doesnt matter what the high is doing right this minute.
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Quoting TXEER:
I have a serious question.

What is it that causes these bands of clouds to come Wstward across Africa on a regular basis from August to October?

Thank you!


the african easterly jet and tradewinds
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2126. jipmg
I see a small eye on bill via visible satellite popping out
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Just got a tornado in Cape Coral. Claudette's presence felt, even though it's a ways off now.
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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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