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 7544:
local news just said that td 3 is getting stronger and will see ts warnings go up for so fla i at 11 am also said it has alot of moisture to get even stronger as the day goes on thats warniings not wathes



I imagine watches/warnings will go up from the PB/Martin County line down to key west
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Quoting hurrkat05:
thank you storm i value your opinion as forecaster but you havent said much about what happens to bonnie when she enters the gom..i give bonnie NO CHANCE OF BECOMING A HURRICANE IN THE GOM...


There is always a chance, even if it is slight, so your observations/synopsis are unfounded. You do have the right to your opinion however, I just don't agree with it. There is a possibility that TS Bonnie may develop into a Hurricane sometime during here voyage through the GOM to parts undetermined at this time.
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Will new models come out with the 11 AM EST advisory?
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A not even tropical storm yet has people acting like nutjobs...



It's not an "act".
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Fox News just said NOAA will declare it (97l) a storm at 11:00. Said a closed center had formed
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still not impresed with its organization yet still gota way to go i think before ts stat
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Quoting Hardcoreweather2010:


Thanks for the info but shouldn't they put a RECORDED stamp on the screen ?


Probably. However, I can tell the satellite he had on the screen was old.

I have no idea why they put recorded shows on......VERY lame.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting CybrTeddy:


at 1500 UTC yes.

So is it TD3 now or still 97L or both?
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Quoting reedzone:


Bad news, any slowness of the invest or speed of the ULL spells for a more favorable environment.
Not only that but the slower it goes the less chance it has of moving into south Florida but rather through the keys or straights.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
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Quoting AllStar17:


That is the recorded Wake Up With Al from 6 am.....it is NOT live, I do not believe.


Thanks for the info but shouldn't they put a RECORDED stamp on the screen ?
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When do the Hurricane Hunters take off?
Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting Drakoen:
Looks like TD3 has building some convection in its northwestern quadrant. Also looks to have slowed down some.
GOES satellite animation


Bad news, any slowness of the invest or speed of the ULL spells for a more favorable environment.
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155. 7544
local news just said that td 3 is getting stronger and will see ts warnings go up for so fla i at 11 am also said it has alot of moisture to get even stronger as the day goes on thats warniings not wathes

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Quoting Drakoen:
Looks like TD3 has building some convection in its northwestern quadrant. Also looks to have slowed down some.
GOES satellite animation


Good morning Drak...Do you see watches/warnings reaching up to our neck of the woods?
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Quoting chrisdscane:



so do i


We may be Key West bound after all! A weekend in the Keys. Thanks Bonnie!
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Quoting louisianaboy444:
Talk about some big swins with the NHC they go from 0 to 80 percent with 95L now 40 to 100 percent with this storm....They need to teach them bright-eyed young inturns to stop swinging with the models lol


Agreed.
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Quoting Hardcoreweather2010:
Rick Knabb on TWC just said that he doesn't think that it will get named before it reaches FL


That is the recorded Wake Up With Al from 6 am.....it is NOT live, I do not believe.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting AussieStorm:
What the heck happened while I was at work, Last time i checked 97L was at 40%, now it's at 100%. Does that mean it's TD3 now or only after 1500 UTC?
Yet, there is little rain in 97L




at 1500 UTC yes.
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What the heck happened while I was at work, Last time i checked 97L was at 40%, now it's at 100%. Does that mean it's TD3 now or only after 1500 UTC?
Yet, there is little rain in 97L


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Quoting StormW:


1.) No.

2.) It should aid in ventilation.


Good Morning Storm,
Do you think the current models will hold strong or might there be another change in the next run due to what is supposed to be an 11am bump in status?
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Quoting CybrTeddy:
Personally, I think this is going to go through the straights and hit the keys
.



so do i
Member Since: July 21, 2010 Posts: 0 Comments: 1181
Rick Knabb on TWC just said that he doesn't think that it will get named before it reaches FL
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Talk about some big swings with the NHC they go from 0 to 80 percent with 95L now 40 to 100 percent with this storm....They need to teach them bright-eyed young inturns to stop swinging with the models lol
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Quoting rossclick:


is there weak steering in the area?


No but the convection may be helping "sucking" the system closer to the convection
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Quoting BradentonBrew:
Where's our Cape Canaveral caster today? Once again, Storm...you hit it on the head. Well done!


I'm a Space program fan.. can I be the Cape Canaveral caster?
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Quoting nola70119:
The intensity of this one willl be easy to monitor, watch the WV loops to see what is happening with all that dry dry air.


Agree because the south side is vacant of anything...
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I live in Key West!! Me no likey!!!! How tronge are we thinking???
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UUL... continues southwest over florida ... will lead to bahama storm to over time move more west...then later into tx...
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Personally, I think this is going to go through the straights and hit the keys.
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Quoting jeffs713:

*getting out the popcorn and drinks*


Popcorn in the morning??? BLEH!!!! I hate the smell of popcorn in the morning.
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Quoting Drakoen:
Looks like TD3 has building some convection in its northwestern quadrant. Also looks to have slowed down some.
GOES satellite animation


Indeed... attempting to get better consolidated. Even in the last 3 to 6 hours the 500MB VORT has become better pronounced as the ULL pulls away rather quickly now. It is also attempting to get a hold of the steering currents as they're a bit weak at this time due to a weakness to its N.

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Quoting Drakoen:
Looks like TD3 has building some convection in its northwestern quadrant. Also looks to have slowed down some.
GOES satellite animation


is there weak steering in the area?
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Anyone care to post an image with the track of the COC over the past 24 hours? I'm having a hard time nailing down the actual direction of movement of the COC.
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Quoting CyclonicVoyage:


I have mucho respect for the NHC but, I have to say, last night I wanted to call the 2am forecaster and ask him what the He** are you looking at, 40%?
Prolly wanted to see the VIS before changing. Don't forget yesterday PM the upper air environment was still quite unconducive...
Member Since: October 25, 2005 Posts: 19 Comments: 22846
129. MahFL
59 mins to go lol.
Member Since: June 9, 2004 Posts: 0 Comments: 4029
Quoting Drakoen:
Looks like TD3 has building some convection in its northwestern quadrant. Also looks to have slowed down some.
GOES satellite animation


Structure gradually improving.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
127. IKE
Quoting CJ5:


Ike, how are things in LA? I will be driving through on the way to Destin next week. Thankfully, I got the hurricane insurance but I would rather go on vacation. Maybe, with some luck, I can.


They're hot and humid here.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting BahaHurican:
Thats MayaGUANA, MiamiH09.

And it looks like it's more south of the Srn tip of Acklins to me. I'll call my pple in Mayaguana later this a.m. to find out what the wx is like. I know they had some flood warnings given out by the local government officials there.
Sorry, misspelling by me. On visible it looks like that is where the COC is located, however on infrared it looks to be south of Mayaguana.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Where's our Cape Canaveral caster today? Once again, Storm...you hit it on the head. Well done!
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Thanks Storm. I hope you are loaded up on coffee, it looks like it will be a long day for you.
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Thats MayaGUANA, MiamiH09.

And it looks like it's more south of the Srn tip of Acklins to me. I'll call my pple in Mayaguana later this a.m. to find out what the wx is like. I know they had some flood warnings given out by the local government officials there.
Member Since: October 25, 2005 Posts: 19 Comments: 22846
121. 7544
all we need are the plots now stay tuned
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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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