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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525. IKE
TD4 looks impressive on satellite.

I'll be surprised if it's not a TS.

Pressures high, not sure why?
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524. JRRP
Link
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Link

Hi resolution windsat over Bill a couple of hrs ago...
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Is TD4 showing signs of a westward jog?
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SO.....thoughts now are that Bill will be a Fish Storm
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Play nice super brains Drak and Conch!!!!
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Quoting AllStar17:


To the south and west, right. That may not be entirely good. If the system hangs on and gets into the extreme TCHP of the Caribbean this could blow up rapidly if it hangs on. I do not see this going over any of the islands, I see it going south of the islands.


Allstar17. What do you mean about going south of the islands. The Caribbean islands stop at Trinidad whish is further south than Barbados.
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Quoting ConchHondros:


No, but if we want we can go there


Welcome to my ignore list.
Member Since: October 28, 2006 Posts: 57 Comments: 29864
WOW, bill has a weakening flag, ANA has a rapid dissipating flag, and 04L will probably become claudette at 12:30 or 1
what would it POSSIBLY mean for Florida if Bill curves over the Bahamas? TIA
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Quoting atmoaggie:

Yeah, but he wanted to evacuate all of coastal LA 6 days ago, too. He is THE blog doomcaster. I see he dropped the "very dangerous situation" so someone would actually read his posts without a smile.
Do you know when to actually pay attention to this guy? Otherwise you will be living out of a suitcase and moving around a lot.

Seriously. Not picking on anyone, just letting you know whom you are getting info from.
One of his posts yesterday mentioned an airplane and reconnaissance.

Stormno, what kind of plane do you fly, and what sort of telemetry do you use to report back to your office?
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Quoting atmoaggie:

Yeah, but he wanted to evacuate all of coastal LA 6 days ago, too. He is THE blog doomcaster. I see he dropped the "very dangerous situation" so someone would actually read his posts without a smile.
Do you know when to actually pay attention to this guy? Otherwise you will be living out of a suitcase and moving around a lot.

Seriously. Not picking on anyone, just letting you know whom you are getting info from.


Really..I listen to everyone... everyone has their inisght to offer.. I listen and watch...take it all in.. We won't evacuate anyway. Was gone for Katrina. I am a nurse and should have been here to help sooner. Was stuck in GA and feeling guily I was not here.
I appreciate all who input here.
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Quoting windsurfer68:
What is spinning at 25' N , 70' W? What kind of system is it? the center is right on 25' N heading towards Florida. Thanks.


An upper level low.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting extreme236:


If it in fact moves over Hispanola and Cuba as a weak TS or TD is it definitely done for.


Yes, but I am not sure if it will, it may just move through the Caribbean
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I'm sorry for anyone getting bad storms but, I am happy nothing is coming to Tampa!
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Ana's current recon:

Flight Level Wind: 32 knots
(~ 36.8 mph)

Lowest Pressure: 1005.1 mb
(~ 29.68 inHg)
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What is spinning at 25' N , 70' W? What kind of system is it? the center is right on 25' N heading towards Florida. Thanks.
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Quoting Drakoen:


And the NHC called that as well. It is your way of repudiating someone.


No, but if we want we can go there
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Quoting Drakoen:
Ana is tracking way off her forecast points.

Hi Drak, The last few frames on the NOAA site shows a consistant flare-up of convection further to the North of where Ana's position was recorded. Also, Bill seems to be taking a slight turn South. I know amateurs always see a lot that isn't there, however, I would like your opinion.
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Quoting ConchHondros:


Dont misunderstand, I wasnt calling you out. I pointed out that you called it last year, and that a lot of others called every storm a fish...maybe I could have worded it better...no offense


And the NHC called that as well. It is your way of repudiating someone.
Member Since: October 28, 2006 Posts: 57 Comments: 29864
Bermuda might to keep a eye out for bill.This mornings GFS ensemble members.
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Quoting AllStar17:
Still hanging on. I think there is still a circulation, just an ill-defined one. However, we all know what happened with Katrina, as well as Andrew, so we should not write Ana off yet.



If it in fact moves over Hispanola and Cuba as a weak TS or TD is it definitely done for.
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Quoting Ossqss:
When does the new GFS run come out?

This 12 Z GFS run? It has graphics out to 72 hours so far.

24 hours:
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TD 04:

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 16 AUG 2009 Time : 144500 UTC
Lat : 28:39:30 N Lon : 84:33:59 W


CI# /Pressure/ Vmax
2.8 /1002.0mb/ 41.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.8 3.1 3.5

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -36.4C Cloud Region Temp : -53.5C

Scene Type : CURVED BAND with 0.79 ARC in LT GRAY

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.2T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

****************************************************


NHC - should really upgrade.

TS Ana:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 16 AUG 2009 Time : 144500 UTC
Lat : 14:47:04 N Lon : 55:43:02 W


CI# /Pressure/ Vmax
2.5 /1005.0mb/ 35.0kt


Final T# Adj T# Raw T#
(3hr avg)
2.5 2.6 3.5

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -49.0C Cloud Region Temp : -20.9C

Scene Type : CURVED BAND with 0.79 ARC in MD GRAY

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : ON

****************************************************

TS Bill:


UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 16 AUG 2009 Time : 151500 UTC
Lat : 12:06:57 N Lon : 38:27:27 W


CI# /Pressure/ Vmax
3.3 / 996.4mb/ 51.0kt


Final T# Adj T# Raw T#
(3hr avg)
3.1 3.4 3.4

Latitude bias adjustment to MSLP : +0.0mb

Center Temp : -12.8C Cloud Region Temp : -40.0C

Scene Type : SHEAR (0.04^ TO DG)

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : ATLANTIC
Dvorak CI > MSLP Conversion Used : ATLANTIC

Tno/CI Rules : Constraint Limits : NO LIMIT
Weakening Flag : ON
Rapid Dissipation Flag : OFF

****************************************************



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Quoting AllStar17:


Where did you get that? Do you have a loop?
yes, it's from a local news station here in Miami, Local 10, here is the loop:
Link
Quoting cycloone:
Does anyone think bill will be a fishy-cane??
I'm confused


Me too. to get to Bermuda, Bill would have to track past where Ana is now, but Ana's predicted to go west. Maybe it's a gender thing.
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Quoting Drakoen:


I go by what the models say. Don't call me out as if i'm the only person that said that.


Dont misunderstand, I wasnt calling you out. I pointed out that you called it last year, and that a lot of others called every storm a fish...maybe I could have worded it better...no offense
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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://www.guiweather.com/kml.html

Member Since: July 15, 2005 Posts: 3 Comments: 1262
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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://www.gearthblog.com/blog/archives/2008/07/live_hurricane_hunter_missions_in_g.html
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Still hanging on. I think there is still a circulation, just an ill-defined one. However, we all know what happened with Katrina, as well as Andrew, so we should not write Ana off yet.

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Quoting AllStar17:


To the south and west, right. That may not be entirely good. If the system hangs on and gets into the extreme TCHP of the Caribbean this could blow up rapidly if it hangs on. I do not see this going over any of the islands, I see it going south of the islands.


It moving north of due west. No heading in a true Westerly direction.
Member Since: October 28, 2006 Posts: 57 Comments: 29864
Quoting InTheCone:


Is currently running.....
GFS


Thanks, the last run had a vanishing Ana. In my novice eyes :)
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The 00z ECMWF has multiple trofs which should help keep the eastcoast out of harms way in the coming days.
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Quoting canesrule1:


Where did you get that? Do you have a loop?
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Quoting stormpetrol:
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.


Yeah, I think the north shift was an illusion from a convection build up.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting Tazmanian:
dos any one think ANNA is now a open wave???


The circulation is definitely weaker than it was yesterday and hard to see but it could be that the thunderstorms are just blowing up over the circulation.

We should know soon if RECON finds one or not.
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>

Upper Level Low
Quoting Dakster:


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?

What? They are are not out of the way, Bill in the middle of Atlantic getting stronger, Ana still there approaching the Leewards, and T4, making down fall in fl panhandle later tonight as TS Claudette.
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Does anyone think bill will be a fishy-cane??
I'm confused
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Quoting ConchHondros:
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


I go by what the models say. Don't call me out as if i'm the only person that said that.
Member Since: October 28, 2006 Posts: 57 Comments: 29864
Quoting Drakoen:
Ana is tracking way off her forecast points.


To the south and west, right. That may not be entirely good. If the system hangs on and gets into the extreme TCHP of the Caribbean this could blow up rapidly if it hangs on. I do not see this going over any of the islands, I see it going south of the islands.
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Quoting szqrn1:
Stormno..
..last night you warned about TS in Gulf this AM.. you called that correcty... I am listening and watching here in MS

Yeah, but he wanted to evacuate all of coastal LA 6 days ago, too. He is THE blog doomcaster. I see he dropped the "very dangerous situation" so someone would actually read his posts without a smile.
Do you know when to actually pay attention to this guy? Otherwise you will be living out of a suitcase and moving around a lot.

Seriously. Not picking on anyone, just letting you know whom you are getting info from.
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Quoting WPBHurricane05:
If HH find a stronger TD 4 the NHC will immediately issue a special update.
exactly, due to its proximity to land
Quoting Drakoen:
04L is SSE of Apalachicola


Landfall around Panama City, maybe? Did turn more to the WNW, NW for sure... maybe will stop the rain from moving into the Tallahassee area (darnit!)

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Quoting Ossqss:
When does the new GFS run come out?


Is currently running.....
GFS
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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


I'll give you props, you called the system in the Gulf correctly. Now, what do your 'sources' think it's going to do?
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.