Tropical Depression Three forms

By: Dr. Jeff Masters , 3:42 PM GMT on July 22, 2010

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Tropical Depression Three has formed over the Bahama Islands, and appears poised to become Tropical Storm Bonnie later today. Satellite images of TD 3 show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. The surface circulation center is exposed to view, thanks to strong upper-level winds out of the southwest that are creating about 20 knots of wind shear. This wind shear is due to the counter-clockwise circulation of air around a large upper-level low pressure system over Florida that is moving west at about the same speed TD 3 is. Water vapor satellite loops show a large area of dry air is associated with the upper-level low pressure system, and this dry air is hindering development of TD 3. The storm is attempting to wrap a curved band of clouds around its center, on its west side. If TD 3 is able to do this, the center will be protected from shear and dry air, and more significant strengthening can occur. Surface observations in the Bahamas and several nearby ships have shown top winds in TD 3 of up to 35 mph, so the storm is close to the 40 mph winds needed to be classified as a tropical storm.


Figure 1. Water vapor satellite image showing dry air (brown colors) associated with the upper-level low over Florida. Image credit: NOAA/NESDIS.

Track Forecast for TD 3
The storm is in a fairly straightforward steering current environment, and TD 3 should progress steadily to the west to west-northwest through Saturday. This will bring the storm ashore over the Florida Keys or South Florida on Friday, and into the Gulf of Mexico on Saturday. The latest set of model runs from 2am EDT (6Z) had the advantage of having data from a flight of the NOAA jet last night, so we have higher confidence than usual in the track of TD 3 over the next two days. The location of TD 3's final landfall along the Gulf of Mexico coast has the usual uncertainties for 3 - 4 days, with the various models calling for landfall somewhere between the upper Texas coast and the Florida Panhandle coast. Given the uncertainties, the move halt operations in the Deepwater Horizon blowout recovery effort are probably wise.

Intensity Forecast for TD 3
The primary detriment to development of TD 3 for the next three days will be the presence of the large upper-level low to its west. As long as this low remains in its present location, relative to TD 3, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of TD 3 to no more than about 10 - 15 mph per day. If the upper-level low slow down a bit, relative to TD 3, more shear will affect the storm, potentially weakening it. Conversely, if the upper-level low picks up speed and pulls away from TD 3, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it would not take much of an additional separation between TD 3 and the upper level low to substantially reduce shear and allow TD 3 to intensify into a hurricane on Saturday. I put the odds of TD 3 making it to hurricane strength in the Gulf of Mexico at 20%.

98L
An area of disturbed weather (98L) has developed in the Gulf of Mexico's Bay of Campeche. This system is under a low amount of shear, 5 - 10 knots, and may barely have enough time to organize into a tropical depression before making landfall along the Mexican coast a few hundred miles south of the Texas border on Friday.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Next update
I'll have an update between 3 - 4 pm, when the Hurricane Hunters will be in the storm. I'll also speculate on the possible impact the storm will have on the oil spill region.

Jeff Masters

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Storm thank you for your update, as usual it is most appreciated. It appears that TD3 is pulling in moisture from the SSW and closing the center of circulation. The movement N of WNW is troubling to those of us who live in Miami and SE Florida.
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Quoting StormW:


Well, I've read a couple of things on that...some say yes you do, and another read I did said that recon figures that in in their report. So, hard to say which one is correct, although for years, that's been the belief...that you add to the eastern side, relative to the center and storm motion.
Thank you
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Quoting Hurricanes101:


I know there is, it has not yet gotten to TD 3, look at the coordinates again






Sorry , im new at this.
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Quoting DestinJeff:


ROFLMAO
Member Since: July 7, 2010 Posts: 0 Comments: 5672
Just did an analysis on TD3 and 98L.
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415. MahFL
"In Florida, crews removed booms intended to protect waterways in the Panhandle from oil. High winds and storm surge could carry the booms into sensitive wetlands."

That makes no scense, you'd think they'd leave them just incase they STOPPED some oil. What's worst booms or oil ?

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Latest NHC postition of center, see the big L.

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Quoting DestinJeff:



TeaseCaster
Member Since: June 26, 2006 Posts: 0 Comments: 1115
its been a t.d. since this morning. at least the news has been saying that its a t.d. all morning. how does everyone feel about the track? nhc has been pretty good this season so far. how does everyone feel about the strength. think it will be a t.s. or a hurricane? what would have to happen and how likely is it for t.d.3 to become hurricane bonnie? thanks in advance:) i love to get the different opinions of everyone on the blog. it amazes me to learn how many different things can happen to change things in an instant.
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Quoting stormhunter23:

Yeah , there's a Air force Aircraft
Link


I know there is, it has not yet gotten to TD 3, look at the coordinates again
Member Since: March 10, 2010 Posts: 1 Comments: 7490
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Quoting Hurricanes101:


recon is not there yet

Yeah , there's a Air force Aircraft
Link
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Quoting Drakoen:
Dry air still affecting TD3


Any t-skew chart available from the Bahamas?
Member Since: March 19, 2009 Posts: 0 Comments: 1421
Quoting Grothar:


Oh, yes it is! And stop arguing with your elders! I won't let you post any more of my globes.
I'll stop arguing when you stop posting my CIMSS images! LOL!
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404. unf97
Quoting StormW:
Back!


Good afternoon sir!
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ok poll question

98L becomes what before landfall?

A) stays 98L
B) TD 4
C) TS Colin
D) Hurricane Colin
Member Since: March 10, 2010 Posts: 1 Comments: 7490
Quoting StormW:
Back!


Hello StormW. Does the ridge have a weakness causing TD3 to move NW? Is this just an interim thing?
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Quoting Hurricanes101:
The center is not exposed anymore
Agreed. It is best noted here.
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Quoting MiamiHurricanes09:
No it is not.



Oh, yes it is! And stop arguing with your elders! I won't let you post any more of my globes.
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Quoting stormhunter23:
Highest wind found in TD3: 39.1 mph from the ESE


recon is not there yet
Member Since: March 10, 2010 Posts: 1 Comments: 7490
Quoting StormW:
Back!


yay think itll get to 50 before florida
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Dry air still affecting TD3
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Highest wind found in TD3: 39.1 mph from the ESE
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Quoting CybrTeddy:


97L? You mean TD3 right?
Yeah..
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The center is not exposed anymore
Member Since: March 10, 2010 Posts: 1 Comments: 7490
Quoting StormW:
Back!
wiil you please answer post 261?
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30 min till next advisory
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Quoting Patrap:
A Weak Hurricane?

...real tomato catsup Eddie?


Nothin' but the best....
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Quoting muddertracker:
Link

OK..so right now it looks like the ULL is moving for south west into Florida. It is no longer "pulling" 97l's convection straight north...it's actually pulling it more north west, and west...could this help 97l wrap up:?

(Be kind...this is WAY above my pay grade)


97L? You mean TD3 right?
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Quoting DestinJeff:
Somebody throw some singles at her ... she's putting on a good show.


LMAO!!!!
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Quoting Patrap:
A Weak Hurricane?

...real tomato catsup Eddie?


A Little bit pregnant?
Member Since: October 30, 2007 Posts: 0 Comments: 270
Looks to me that 03 will become a TS by tonight and that it has a great chance of becoming a Cat. 1 in the GOM.
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Quoting cg2916:


The center is exposed.
No it is not.

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I hope it sends some rain our way....my plants & grass are beggin for rain!! I'm tired of watering them! lol
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Quoting scott39:
Patrap, Do you know whats causing the intensity forecast to be low in the GOM, when its covering so much water? Maybe because they had the, now gone, tagging ULL in the forecast???


The ULL Holding the throttle Back...for now still.

But Intenisty is the lesse Known variable compared to track.

Esp with such a "potential Track "...intensity forecast can and usually do change,..in the GOM
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Link

OK..so right now it looks like the ULL is moving for south west into Florida. It is no longer "pulling" 97l's convection straight north...it's actually pulling it more north west, and west...could this help 97l wrap up:?

(Be kind...this is WAY above my pay grade)
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Quoting cg2916:


The center is exposed.


Yup.
Member Since: March 19, 2009 Posts: 0 Comments: 1421
379. unf97
Quoting Jeff9641:


Are you noting this steady NW movement as well and gaining strength as well. I think we have a 45 mph storm right now.


My thinking from yesterday was that once the system reached the central Bahamas, it would begin to consolidate and strengthen. That appears to be happening now Jeff. Also, the COC redeveloped a little farther north in the past 12 hours as well. I have been looking at the visual satellite loop, and it appears the COC is moving a little more north of due west at the moment. I think this will be the case probably for the next 12-24 hours until the ULL moves a little more farther away into the GOM. After that, I think TD 3 will probably resume more of a W-W/NW track when it crosses the South FL late tomorrow into Saturday when the ridge begins to strenghten and build back in over the cyclone.
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Quoting ElConando:


Surprised you don't have eddye one ignore.



Some are kept seen for material only..

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Patrap, Do you know whats causing the intensity forecast to be low in the GOM, when its covering so much water? Maybe because they had the, now gone, tagging ULL in the forecast???
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Quoting Grothar:
Convection doesn't seem to be wrapping around the center yet.



The center is exposed.
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Quoting Orcasystems:
Texas anyone?



AOI

AOI

AOI

AOI

Landfall Points

TS BUSTED FORECAST ALIBI

I know all the models show a strong turn to the north, and the storm is heading nw, but the reuns of the models show it moving more west with each run. The previous two storms went across Mexico. Is it possible this storm will also tend to track west and hit south Texas, (padre isalnd), or Tx/MX border??
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Quoting Patrap:
A Weak Hurricane?

...real tomato catsup Eddie?


Surprised you don't have eddye one ignore.
Member Since: September 6, 2009 Posts: 2 Comments: 3712

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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.