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 Skyepony:


I think it has helped keep her pulled south & has kept her alive when her convection gets blown off.


So Bill has an umbilical cord?

?_?
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1774. mkmand
Bill is a beautifull storm. It'll be fun to track.
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1773. GatorWX
Quoting Drakoen:
GFS ensemble members are tightly clustered:


lol, south FL!
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1772. jipmg
A couple of models see it breaking through the trough after it moves NW or NNW (Andrew anyone?)
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Funny. Ana's center will pass through the islands without the inhabitants knowing until the eastern convection follows.


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1770. Michfan
Quoting CatastrophicDL:

I don't think they are close enough to effect each other. I think they have to be within 600 miles of each other. Anyone else remeber how close they have to be?


If i remember right its more like 500 miles or less.
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lolz, why is Drak getting attacked for stating what the models are indicating?

Because if you state that the storm is going anywhere but right at someones door step they call you a downcaster...you gotta learn to just ignore it
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Quoting CatastrophicDL:

I don't think they are close enough to effect each other. I think they have to be within 600 miles of each other. Anyone else remeber how close they have to be?


Depends on the barometric pressure of both systems.
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Quoting FloridaTigers:
lolz, why is Drak getting attacked for stating what the models are indicating?


Don't know, must be the same kind of reason why people where getting attacked earlier today for saying they think Bill will go more west, makes as much sense as the rest of the blog :). Two opposing sides both with good facts to both.
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Quoting hurristat:


More like a question of when. Two years from now, in the EPac, there will most likely be a storm named Hilary. Unfortunately, it's Hillary Clinton, not Hilary.

And LOL I accidentally just typed "Clintron" instead of "Clinton."


lol, oh I see.
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Quoting Skyepony:


Yes that was the tropical wave that turned into Claudette.


Thanks for the info. I thought it looked a little more omnious than the normal afternoon tstorms here.
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1764. Skyepony (Mod)
Quoting 996tt:
Bill is still keeping Ana on a short leash. Does that umbilical cord type of thing affect Ana at all?


I think it has helped keep her pulled south & has kept her alive when her convection gets blown off.
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Quoting winter123:
http://www.ssd.noaa.gov/goes/flt/t2/flash-rb.html

hit "trop points", Bill is going well north of forecast track.

no he isn't.

he's pretty much right on track. could be .1 north of where the track is but that's like 6-8 miles, lol.
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1762. KEEPEROFTHEGATE (Mod)
Quoting Drakoen:
According to the models Bill is one for the fishes or Bermuda... Not much of a difference to me.
its heading to the triple nickel drakoen

15.5n/55w
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I live on Parker Bayou just a few miles east of Panama City. Just walked down to the dock. Low fast moving clouds to the east and south. Some wind up in the trees, but mostly just a light breeze. Blue sky directly overhead. We just finished putting up lawn chairs, etc. and will add extra anchors to keep the boats away from the dock (we have a small boatyard) but are not moving and anchoring boats in deeper water. With the storm approaching from the southeast we should have no problem with storm surge--in fact wind should drive water out of the bay. Storm seems to have slowed down which may give it more time over water, but I don't think enough time to become seriously dangerous. Mainly will have limbs, moss, leaves etc. and probably lose power. We have big live oaks and unless one of those limbs goes through the roof we should have no real problems. Will give you an update later.
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Quoting Drakoen:
According to the models Bill is one for the fishes or Bermuda... Not much of a difference to me.

I think bill would went similar like hurricane dean. But given the SST's in the caribic i think this will not happen.
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Member Since: May 21, 2006 Posts: 5091 Comments: 115437
Quoting 996tt:
Bill is still keeping Ana on a short leash. Does that umbilical cord type of thing affect Ana at all?

I don't think they are close enough to effect each other. I think they have to be within 600 miles of each other. Anyone else remeber how close they have to be?
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Quoting Weather456:
where's Hilary when you need her



More like a question of when. Two years from now, in the EPac, there will most likely be a storm named Hilary. Unfortunately, it's Hillary Clinton, not Hilary.

And LOL I accidentally just typed "Clintron" instead of "Clinton."
Member Since: October 15, 2008 Posts: 11 Comments: 2312
1756. TopWave
Currently, Bills track looks somewhat familiar to that of Hurricane Isabel in 2003. I wonder if Bill will be another annular storm
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1755. Michfan
Quoting JAC737:
I really get a kick out of you all. There's all this, "Where's it going? Am I in the clear? Am I going to get hit?" and someone says, yes and someone says no and someone says maybe. And then it's all, "You're not an expert! You're not a meteorologist! Don't you say so and so is in the clear! Don't you say it's heading west! It's a wobble!" So you yell at each other for predicting and you yell at each other for warning each other.


Thats pretty much how this blog goes on a daily basis during the active part of the season. It will never change.
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Quoting GatorWX:
Taz, do you speak a second language, if so, are you from another country? I know I've seen you on here for years, but don't remember ever asking or seeing anyone else ask. Just curious.


Though considered by some, California is not out of this country....LOL
Member Since: July 31, 2006 Posts: 56 Comments: 8112
lolz, why is Drak getting attacked for stating what the models are indicating?
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1752. Drakoen
GFS ensemble members are tightly clustered:
Member Since: October 28, 2006 Posts: 57 Comments: 30724
Quoting CapeFish:


Of course the track shifted, but she never moved outside of the cone. Just because she stayed to the southern part of the cone, she did not go against the forecast. The entire cone is the forecast.

Thus, in the case of Bill, even if he skirts the southern part of the forecasted cone, which is very possible, he should barely skirt the northern islands.


lol but check out the size of the cone
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Quoting BajaALemt:
Hmmmmm fl, it's up for me.

Try this and click 'Beach Cam' (faces SSE) .... the other cam 'Sunset Cam' faces SW

EDIT: I refreshed and all the cams are down...hopefully they'll come back up
Thanks Baja
Also Beach View Webcams
Look just right of the center of this picture (St George Island). Is that a boat? Looks like a sail boat.

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Thanks Kman . I am a wait and see guy as well but That thing is getting bigger and kinda mean looking. I was hoping its size would not effect the troughs ability to bounce it. i guess we will know in a few days.. thanks again for the reply.
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1748. JAC737
I really get a kick out of you all. There's all this, "Where's it going? Am I in the clear? Am I going to get hit?" and someone says, yes and someone says no and someone says maybe. And then it's all, "You're not an expert! You're not a meteorologist! Don't you say so and so is in the clear! Don't you say it's heading west! It's a wobble!" So you yell at each other for predicting and you yell at each other for warning each other.
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1747. Skyepony (Mod)
Quoting champagnedrmz:
Originally I am from New Hampshire. The cute doggy in my avatar is from Florida though.
I wanted ask one more thing was the storms yesterday going over St Lucie county from the now named Claudette?


Yes that was the tropical wave that turned into Claudette.
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1746. 996tt
Bill is still keeping Ana on a short leash. Does that umbilical cord type of thing affect Ana at all?
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1745. GatorWX
Taz, do you speak a second language, if so, are you from another country? I know I've seen you on here for years, but don't remember ever asking or seeing anyone else ask. Just curious.
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http://www.ssd.noaa.gov/goes/flt/t2/flash-rb.html

hit "trop points", Bill is going well north of forecast track.
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Quoting Weather456:


what?


look at Ana's 5 day point when she tropical depression 2.


Look at where is now.

You gonna watch that loop and tell me Ana track did not shift?



Of course the track shifted, but she never moved outside of the cone. Just because she stayed to the southern part of the cone, she did not go against the forecast. The entire cone is the forecast.

Thus, in the case of Bill, even if he skirts the southern part of the forecasted cone, which is very possible, he should barely skirt the northern islands.
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For those wishing to accurately determine Bill's speed, here is a handy dandy lat/long distance calculator. Just plug in the last two (accurate) fix points. Key word accurate.

L/L Distance Calculator
Member Since: July 15, 2005 Posts: 3 Comments: 1270
Quoting Funkadelic:
The models will continue to shift if keeps moving fast like he is. But I still dissagree with 20-23mph lol


This makes a lot of sense.....I am interested in the speed at the 5pm update. The faster he is moving the further to the left the models will shift.
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where's Hilary when you need her

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Bill is a monster of sheer size.
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Quoting Funkadelic:
The models will continue to shift if keeps moving fast like he is. But I still dissagree with 20-23mph lol
dont u mean bill's models will continue to shift southward if it continues its very fast speed.
Quoting rareaire:
afternoon kman! do you think bill will go north or are you of the impression it gets much bigger much faster and goes west through that trough like me thru a cheesecake!


Cheesecake eh LOL

The stronger Bill becomes the more it will be inclined to go N and the stronger the ridge would have to be to hold it on a due W or N of W track. It will all come down to timing, ie. speed and strength of Bill versus evolution of the trough and it propagating to the East.

I certainly have no way of knowing how this will play out. It's sort of like seeing a car heading for an intersection and being told that another car is expected to come down another road in the near future and then being asked whether you think they will collide LOL.
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some showers moving into the local area

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1733. jipmg
Quoting WPBHurricane05:
18Z early for Bill.

What do you know...west they go!


I cant see it
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1732. jake436
Thanks hurristat, Michfan, and KimB. Do we also have a name for the phenomenon that occurs on this board when things get active? lol.
-
I don't understand making fun of TWC for calling this weekend's events "Atlantic Explosion" of whatever they call it. It IS an explosion. From 0-0-0 to 3-0-0 in one day? Explosion.
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I live in Massachusetts (Cape Cod).
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According to the models Bill is one for the fishes or Bermuda... Not much of a difference to me

Same here i pray Bermuda doesn't take a direct hit...this thing could be a monster
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Quoting champagnedrmz:
Originally I am from New Hampshire.


Oh. Nevermind.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
1728. Drakoen
Quoting seminolesfan:
And everyone knows that those simple early cycle models are the ones that carry the most consensus weight and have very high verification rates, right?


The dynamic models take it out to sea as well.
Member Since: October 28, 2006 Posts: 57 Comments: 30724
1726. GatorWX
*repost*

Quoting Weather456:
Those of you on the right side is going to get some pretty gusty winds. 50 knots + forward speed



Meanwhile, Bill's eastern eyewall



Thanks 456 for providing the microwave loop. I guess my pseudo-eyewall theory was incorrect as it appears it was another vorticy or perhaps the center relocated, though not as likely, I think it was already too well developed for that and virtually no shear at that time. I think it wsas just a vorticy, but still most likely contained the strongest winds. You can see what I'm referring to in the first few frames of the loop.
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Hey Pat, ya still around?

What's Claudette doing?? Is she trying to stall or possibly relocate her center a bit? I'm not so sure about a relocation of the center as I've yet to see anything to prove that, but it's definitely in the realm of possibilities.
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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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