Tropical depression forming over the Bahamas

By: Dr. Jeff Masters , 1:29 PM GMT on July 22, 2010

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A tropical wave (Invest 97L) over the eastern Bahama Islands has developed a closed circulation at the surface, and has become a tropical depression or tropical storm. Here is the text of the Special Tropical Weather Outlook from NHC at 8:25am EDT today:

Visible satellite images and observations from the Bahamas indicate that the area of low pressure in the southeastern Bahamas has become better organized and a closed circulation has formed. Advisories on a tropical depression or a tropical storm will be initiated at 11 am EDT...1500 UTC today. This advisory will likely include tropical storm watches and warnings for portions of the Bahamas and southern Florida.

Satellite images of 97L show a modest area of heavy thunderstorms that have slowly increased in intensity and areal coverage this morning. Water vapor satellite loops show a large area of dry air lies to the west of 97L, over Florida. This dry air is associated with a large upper-level low pressure system that is moving west at about the same speed 97L is. The counter-clockwise flow of air around the upper low is bringing about 20 knots of wind shear to 97L. Surface observations in the Bahamas and several nearby ships have shown top winds in 97L 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 97L
The storm is in a fairly straightforward steering current environment, and 97L 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 97L over the next two days. The location of 97L'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 97L
The primary detriment to development of 97L 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 97L, it will bring wind shear of about 20 knots and dry air into the storm. This will limit the intensification potential of 97L to no more than about 10 - 20 mph per day. If the upper-level low picks up speed and pulls away from 97L, the storm may be able to intensify at a faster rate. None of the computer models is calling for that to happen, but it is possible. I put the odds of 97L 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.

I'll have an update after NHC releases their 11am advisory package.

Jeff Masters

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Quoting StonedCrab:


WSVN is too busy taking their HYSTERICAL pills.
They like to be vibrating on the set as they scare the daylights out of folks.
LOL!! That's why I'm watching Local 10.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
ULL appears to be getting pinched off West of TD3. May not inhibit development as much as once thought.
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Quoting oracle28:
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB

OMG
maybe they are putting out 2 advisories, one for each lol
Member Since: March 10, 2010 Posts: 1 Comments: 7484
467. 900MB
Cue the Jeopardy theme song!
Member Since: June 11, 2006 Posts: 0 Comments: 664
Quoting MiamiHurricanes09:
...*Presses F5*...*Waits for WSVN special report*...


WSVN is too busy taking their HYSTERICAL pills.
They like to be vibrating on the set as they scare the daylights out of folks.
Member Since: October 30, 2007 Posts: 0 Comments: 270
Quoting CybrTeddy:


Interesting.. who's his teacher?


they call him mr rackers hes new though
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Quoting Grothar:
Navy site link, but no data.

Link
Good Morning Grothar. You have WU mail at the time of this post sir.
Member Since: September 27, 2007 Posts: 1 Comments: 20933
Quoting Abacosurf:




I think it was an eye replacement cycle. only 5 mph decrease.

I was on Great Guana Cay in Abaco. It was not weak. 150 mph sustained winds for over 12 hours. 2 plus hour eye passage. Gusts recorded to 221 MPH!!!



Camille strength!
Member Since: September 2, 2006 Posts: 110 Comments: 6874
*F5..F5..F5..sips orange juice..pets the dog..changes channels..F5..F5..F5......
Member Since: March 10, 2010 Posts: 1 Comments: 7484
People, if u are going to reference Katrina/Wilma/Rita/Ivan/Andrew/David etc, please give CORRECT information. Katrina was NOT still a depression at 80W.... it was a cat 1 getting ready to hit Miami...

I'm still saying that while this storm may have some similarities to the aforementioned storm from 2005 in term of current location, there are some dissimilarities which are likely to lead to differences in track, forward speed, wind strength and even size. Let's observe this one in realtime, not in reminisce-time...
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THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB
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They better post it soon, anarchy might soon engulf the blog if they don't.
Member Since: July 8, 2005 Posts: 259 Comments: 23878
Good morning.
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Jul 22, 2010 7:18 AM

As of Thursday morning, a broad upper-air trough of low pressure is producing numerous showers and thunderstorms across the southern Bahamas through Hispaniola. An area of low pressure at the surface is trying to develop near 22 north and 75 west. However, the upper-air trough is producing moderate to strong wind shear across the system, displacing the showers and thunderstorms to the east and northeast of any area of surface low pressure. This wind shear is the limiting factor in development at this time.

Regardless of whether this feature develops or not, locally heavy rain will fall across Hispaniola, eastern Cuba and the Bahamas today. The locally heavy rain will shift over southern Florida by tonight and continue through the day Friday as this feature moves in a general westward motion. Along with the rain, winds may gust to 40 mph at times.

The current forecast track will take this feature through the Florida Straits during the day Friday and into the eastern Gulf of Mexico by Saturday morning. It is expected that by the time this feature reaches the eastern Gulf of Mexico, the wind shear currently preventing development will ease, allowing this feature to develop into a tropical depression or tropical storm. This system will continue to move through the Gulf of Mexico and will take aim at the southern Louisiana coast Sunday. All interests in and along the Gulf of Mexico and South Florida should remain vigilant of this system.
Member Since: July 19, 2010 Posts: 0 Comments: 72
Quoting chrisdscane:


my son goes to fiu he over head them say that since one of his teachers works at nhc and there right next to each other


Interesting.. who's his teacher?
Member Since: July 8, 2005 Posts: 259 Comments: 23878
...*Presses F5*...*Waits for WSVN special report*...
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting tropicfreak:


Wait say that again.


Quoting tropicfreak:


Wait say that again.


I think it was an eye replacement cycle. only 5 mph decrease.

I was on Great Guana Cay in Abaco. It was not weak. 150 mph sustained winds for over 12 hours. 2 plus hour eye passage. Gusts recorded to 221 MPH!!!

Member Since: August 28, 2008 Posts: 0 Comments: 304
Quoting CybrTeddy:


Your sources are?


my son goes to fiu he over head them say that since one of his teachers works at nhc and there right next to each other
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98L is nicely organized but it will need to be classified soon to become a named storm.
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They are probably still finishing up the advisory. Stay patient.
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Im here in South Florida-How strong do ya'all think Bonnie will be by the time it gets here?
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Quoting AlexEmmett:

It time has run out its too close to land


Incorrect. TPC and NHC says it has a day or so left over water.. I'd say it has 24-36 hours.
Member Since: July 8, 2005 Posts: 259 Comments: 23878
Gang the ULL is not having much impact on Bonnie.....i yes i do think we have Bonnie now.....Those posting that it has no chance of becoming a Hurricane before South Florida should stop posting as this has nearly 48hours to continue to get stronger......i did not say it would become a CANE but, it sure has a Chance to before South Florida!
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98 is moving west, right?
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hahaha sooo funny ( was meant for you) lol...
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StormW brings alot of knowledge and sanity to this site that is for sure.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
Quoting tropicfreak:


Nice features to 98L.


Probably only 24 hours left.
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Quoting jasoniscoolman2010x:
LOOK AT INVEST 98L wow..CLOUD TOP ARE GETTING COLDER.

It time has run out its too close to land
TD #3 and Invest 98L Update with Video
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Quoting earthlydragonfly:

It would be funny if they posted at 11:02... just so they could watch all the calamity here on the blog...
LOL!!
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting tropicfreak:


Nice features to 98L.


seems to me the convection is ahead of the circulation though and it is not as organized as the convective pattern makes it out to be

and it is running out of time
Member Since: March 10, 2010 Posts: 1 Comments: 7484
I find no good reason to not believe that 97L will become a Cat1-Cat2 storm and will track mostly west and be a storm to contend with in the GOM. SE La. or Miss. landfall.
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429. 900MB
Quoting StormW:


In the short term...the ULL will now help ventilate the area...and with 97L firing convection like it is now, that should pretty much take care of the moisture problem. I'm waiting on the 12Z update on the forecast wind shear. The current run shows a fairly conducive upper environment for the next 18 hours or so, before it looses it's upper level anticyclone.

Thanks as always Storm. Have a feeling that this could turn out bigger than expected due to path (not much land interaction), sea temps, and questionable amount of shear. I also don't see really dry air out there (yes, some dry air but not super dry) so i think that will fade from the discussion. Anyway, we'll see.
Member Since: June 11, 2006 Posts: 0 Comments: 664
Quoting Abacosurf:

I think it was a replacement cycle. only 5 mph decrease.

I was on Great Guana Cay. It was not weak. 150 mph sustained winds for over 12 hours. 2 plus hour eye passage. Gusts recorded to 221 MPH!!!


Wait say that again.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
Quoting MiamiHurricanes09:
If there is no 11 AM EDT advisory this blog will be unbearable. LOL, luckily there will be one.

It would be funny if they posted at 11:02... just so they could watch all the calamity her on the blog...
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting chrisdscane:
some of my sources r saying 45mph at advisory

oh crap, and it could only get stonger with those H20 temps
Quoting HarleyStormDude52:


Doug.. If it comes yur way we will expect some webcam action shots of you as it comes in!!!1



The XTREME TEAM will be on it!
Member Since: July 25, 2006 Posts: 0 Comments: 555


Nice features to 98L.
Member Since: September 2, 2006 Posts: 110 Comments: 6874

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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.