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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looks like a rainy day is in store here in panama city beach
Member Since: September 19, 2005 Posts: 0 Comments: 24
Quoting rareaire:
That recurve for Bill is worrisome. To many things have to come to play for that track to be certian. If he keeps moving west the trough may beat it and then its not going anywhere east or if so it may be to littl to late. IMO


Bill hasn't jogged a mile north since leaving Africa. His centre is pretty far south at 12 or 13 degrees. I'm no met, but I wouldn't be surprised if he just keeps on travelling due west and goes straight through the Antilles into the Caribbean.
Member Since: July 20, 2008 Posts: 0 Comments: 2928
Quoting rmbjoe1954:


Thw Weather Channel seems to think the trough MAY not be strong enough or move south in time to pull Bill northward.


Yes...they left that solution open. We are talking about something 5+ days out...very difficult to forecast.

Wait and see...and always be prepared.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
I bet some are grateful that Claudette didn't form a bit more south than the Florida Keys or that it didn't track slower.

It a real good thing this one didn't have enough time.

This is not to say those in her path should not prepare. Treat every one of these storms with respect.
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Quoting canesrule1:
I do expect ANA to resume her TD status at 2, imo, then rapidly intensify when reaching the Bahamas area, imo. Bill is moving WNW to escape the ITCZ it should resume westward movement today.


escape ITCZ?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting rareaire:
That recurve for Bill is worrisome. To many things have to come to play for that track to be certian. If he keeps moving west the trough may beat it and then its not going anywhere east or if so it may be to littl to late. IMO


Thw Weather Channel seems to think the trough MAY not be strong enough or move south in time to pull Bill northward.
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Bill becoming more compact and intense, should develop an eye by tonight.
It looks as though Claudette is beginning to slow a little and go a little more to the WNW than NW... from looking at the latest satellite frames...

i still think Panama City is gonna get pretty much hammered really soon... maybe even Pensacola... we'll see in the next 8-12 hours...
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Quoting nrtiwlnvragn:
0-0-0 to 3-0-0 in 36 hours.


and soon 3-1-0
Member Since: July 24, 2005 Posts: 407 Comments: 19076
So IKE where are we in the count now?
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Quoting Weather456:


Ana has shifted north which isnt a surprise to me.

Bill is moving wnw
I do expect ANA to resume her TD status at 2, imo, then rapidly intensify when reaching the Bahamas area, imo. Bill is moving WNW to escape the ITCZ it should resume westward movement today.
Tropical Storm Claudette,NexSat GOM Loop
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Quoting rareaire:
That recurve for Bill is worrisome. To many things have to come to play for that track to be certian. If he keeps moving west the trough may beat it and then its not going anywhere east or if so it may be to littl to late. IMO


I agree...we have seen this before rare...watch out though...you may end up on Draks ignore list...oh for shame
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611. IKE
Quoting IpswichWeatherCenter:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 16th day of the month at 16:11Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 01

Mandatory Data...

Observation Time: Sunday, 16:07Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 30.3N 86.4W
Location: 45 miles (72 km) between the W and WNW (281°) from Panama City, FL, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 870 meters
Flight Level Wind: From 100° at 17 knots (From the E at ~ 19.5 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 19°C
Flight Level Dew Point: 8°C
Weather (within 30 nautical miles): Thunderstorm(s)
925 mb Surface Altitude: 851 geopotential meters

Optional Data...

Estimated Surface Wind: From 130° at 15 knots (From the SE at ~ 17.2 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 18 knots (~ 20.7mph)


LOL....they just flew over me here in DFS,FL.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Sorry double post. :p
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WOW:
Quoting Grothar:
Hi again 456. Do you also see a slight Northern jog to Ana and slight southern jog with Bill.


Ana has shifted north which isnt a surprise to me.

Bill is moving wnw
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Progster:
Link

Getting breezy south of Apalachicola


I'll bet.. and you will get the right side of the storm too.
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606. JRRP
at this time we had only 1 name storm in 1998
Link
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Tropical Storm Claudette

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Stupid Question Time:

As Claudette tracks inland will this have any effect on the trough that is supposed to come off the east coast and pull Bill eastward?

Thanking you in advance
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TD4, now Claudette showing a very nice presentation on the visible loop:

Floater - Visible Loop
Member Since: July 22, 2008 Posts: 0 Comments: 109
Quoting Weather456:
A very tight curve band, should serve the focal point of an eye featre

we also officially have Caludette



I agree - I wouldn't be surprised if that once Bill develops an eye - that dry air runs away.
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That recurve for Bill is worrisome. To many things have to come to play for that track to be certian. If he keeps moving west the trough may beat it and then its not going anywhere east or if so it may be to littl to late. IMO
Member Since: Posts: Comments:
Correction
000
WTNT64 KNHC 161616
TCUAT4
TROPICAL STORM CLAUDETTE TROPICAL CYCLONE UPDATE...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
1215 PM EDT SUN AUG 16 2009


CORRECTED FOR ISSUANCE TIME

...DEPRESSION BECOMES TROPICAL STORM CLAUDETTE...

DATA FROM THE NOAA DOPPLER RADAR IN TALLAHASSEE FLORIDA INDICATE
THAT SURFACE WINDS ASSOCIATED WITH THE DEPRESSION HAVE INCREASED TO
40 MPH...65 KM/HR...MAKING THE DEPRESSION TROPICAL STORM CLAUDETTE.
DETAILS WILL FOLLOW IN THE 2 PM EDT INTERMEDIATE ADVISORY.

$$
FORECASTER ROBERTS/BRENNAN
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599. jpsb
Yesterday evening? Lol, talk about having to eat major crow! One thing I've learned about the tropics is NEVER say never.
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Claudette is here
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Quoting Weather456:



isnt it suppose to say

11am CDT


They corrected the time on it just now.
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it looks now we have hurricane Bill. looking at recent sat loops from RAMSDIS , an eye feature is seen with Bill. the eye is wobbling around indicative of a streghning system. BILL has resumed WEST TRACK
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Wow, we went from 0-0-0 to 3-0-0 probably 3-1-0 before tomorrow afternoon. Claudette looks very organized, strengthening fast too, Same with Bill and though Bill looks like a out to sea situation but I cant determine that so many days out
Member Since: Posts: Comments:
Quoting CybrTeddy:
000
WTNT64 KNHC 161614
TCUAT4
TROPICAL STORM CLAUDETTE TROPICAL CYCLONE UPDATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
1100 AM EDT SUN AUG 16 2009


...DEPRESSION BECOMES TROPICAL STORM CLAUDETTE...

DATA FROM THE NOAA DOPPLER RADAR IN TALLAHASSEE FLORIDA INDICATE
THAT SURFACE WINDS ASSOCIATED WITH THE DEPRESSION HAVE INCREASED TO
40 MPH...65 KM/HR...MAKING THE DEPRESSION TROPICAL STORM CLAUDETTE.
DETAILS WILL FOLLOW IN THE 2 PM EDT INTERMEDIATE ADVISORY.

$$
FORECASTER ROBERTS/BRENNAN

Claudette!


Yay!! Now Claudette - please die before making landfall.
Member Since: Posts: Comments:
Quoting CybrTeddy:
000
WTNT64 KNHC 161614
TCUAT4
TROPICAL STORM CLAUDETTE TROPICAL CYCLONE UPDATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
1100 AM EDT SUN AUG 16 2009


...DEPRESSION BECOMES TROPICAL STORM CLAUDETTE...

DATA FROM THE NOAA DOPPLER RADAR IN TALLAHASSEE FLORIDA INDICATE
THAT SURFACE WINDS ASSOCIATED WITH THE DEPRESSION HAVE INCREASED TO
40 MPH...65 KM/HR...MAKING THE DEPRESSION TROPICAL STORM CLAUDETTE.
DETAILS WILL FOLLOW IN THE 2 PM EDT INTERMEDIATE ADVISORY.

$$
FORECASTER ROBERTS/BRENNAN

Claudette!



isnt it suppose to say

11am CDT
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Mobilegirl what made you make that call?
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Hi again 456. Do you also see a slight Northern jog to Ana and slight southern jog with Bill.
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0-0-0 to 3-0-0 in 36 hours.
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Quoting WPBHurricane05:


Those aren't my thoughts. I'm very vigilant of Bill.


Me also.
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so now we have three:
000
WTNT64 KNHC 161616
TCUAT4
TROPICAL STORM CLAUDETTE TROPICAL CYCLONE UPDATE...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
1215 PM EDT SUN AUG 16 2009


CORRECTED FOR ISSUANCE TIME

...DEPRESSION BECOMES TROPICAL STORM CLAUDETTE...

DATA FROM THE NOAA DOPPLER RADAR IN TALLAHASSEE FLORIDA INDICATE
THAT SURFACE WINDS ASSOCIATED WITH THE DEPRESSION HAVE INCREASED TO
40 MPH...65 KM/HR...MAKING THE DEPRESSION TROPICAL STORM CLAUDETTE.
DETAILS WILL FOLLOW IN THE 2 PM EDT INTERMEDIATE ADVISORY.

$$
FORECASTER ROBERTS/BRENNAN
post 571

inverted V
Member Since: Posts: Comments:
Quoting stormsurge39:
456 do you thin TD4 is moving NNW or NW? Im looking at the outer bands in the far NW of the system?


nnw
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Please is it going more west or not???
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Quoting mobilegirl81:
Claudette making a left turn.
I guess so!
Member Since: Posts: Comments:
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 16th day of the month at 16:11Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 304)
Tropical Depression: Number 4 (flight originating in the North Atlantic basin)
Mission Number: 1
Observation Number: 01

Mandatory Data...

Observation Time: Sunday, 16:07Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 30.3N 86.4W
Location: 45 miles (72 km) between the W and WNW (281°) from Panama City, FL, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 870 meters
Flight Level Wind: From 100° at 17 knots (From the E at ~ 19.5 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 19°C
Flight Level Dew Point: 8°C
Weather (within 30 nautical miles): Thunderstorm(s)
925 mb Surface Altitude: 851 geopotential meters

Optional Data...

Estimated Surface Wind: From 130° at 15 knots (From the SE at ~ 17.2 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 18 knots (~ 20.7mph)
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RE:TD4 - I remember a storm in the mid-80's that changed direction twice and moved back and forth along the Gulf Coast shoreline. It was crazy. I'm not saying that is what will or is happening but it can and has.
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Quoting extreme236:


I dont think the ADT position for the center is correct.


When you see Positioning Method : FORECAST INTERPOLATION the location is from the NHC track. The imaging algoritm was not able to find a center based on satellite data, so it use the closest position along the forecast track.
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Latest 04L observation:
15:58:30Z 30.317N 87.067W 575.2 mb
(~ 16.99 inHg) 4,774 meters
(~ 15,663 feet) 1013.2 mb
(~ 29.92 inHg)


From 105° at 17 knots
(From the ESE at ~ 19.5 mph)
000
WTNT64 KNHC 161614
TCUAT4
TROPICAL STORM CLAUDETTE TROPICAL CYCLONE UPDATE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042009
1100 AM EDT SUN AUG 16 2009


...DEPRESSION BECOMES TROPICAL STORM CLAUDETTE...

DATA FROM THE NOAA DOPPLER RADAR IN TALLAHASSEE FLORIDA INDICATE
THAT SURFACE WINDS ASSOCIATED WITH THE DEPRESSION HAVE INCREASED TO
40 MPH...65 KM/HR...MAKING THE DEPRESSION TROPICAL STORM CLAUDETTE.
DETAILS WILL FOLLOW IN THE 2 PM EDT INTERMEDIATE ADVISORY.

$$
FORECASTER ROBERTS/BRENNAN

Claudette!
Member Since: Posts: Comments:
A very tight curve band, should serve the focal point of an eye featre

we also officially have Caludette

Member Since: July 24, 2005 Posts: 407 Comments: 19076

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About

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