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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NEXRAD Radar
Miami, Base Reflectivity 0.50 Degree Elevation Range 248 NMI

Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Yep.


wut have city officials said about public transport and the closing of anything
Member Since: July 21, 2010 Posts: 0 Comments: 1089
i am not sure why the bahamas issued warnings so far north with the cone so far south, expecting some significant shifts when recon gets there
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It would seem that the NHC is calling for a northward turn... It is a matter of where it occurs, and probably how strong of a system this is as it approaches the central GOM.
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Come on Stormchaser2007. anything is possible!
only if You have never met a pissed off cajun or redneck women. anything is possible! just poking at you especially if this thing come to TX/LA
Member Since: June 28, 2009 Posts: 0 Comments: 156
might shrink in size to an Andrew....who knows....may be a small buzz saw....

what do we have here?

a spinning LLC closed...
strong convection building....
anti cyclone aloft...
HOT sst's....
nothing in the path but more of the same for the next 24 hours...

again...cat 3 through the keys....anti-cyclone following it...
pucker up time for northern gulf coast...

imho
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Recon Location

Member Since: January 24, 2010 Posts: 0 Comments: 529
Quoting AllStar17:
Looking atthis loop, it appears there is burst of convection directly over the center.
I have been thinking that too, and pointed out this thunderstorm when it popped. The center definitely isn't under the larger blob, but I'm not really convinced that it's quite as far west as 75 either. 74.5-74.8 IMO based on the "yellow" low-level clouds in the NOAA RGB.
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Bring on Bonnie, these heat indicies of 105-110 since May have eaten our lunch. I had heat exhaustion this whole week. I work outdoors!! We can use the rain***
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Quoting clwstmchasr:


Right on? He called for Alex to hit Florida and forecasted 4-5 inches of rain and strong winds for Central FL.

well no he kept sayig Alex was going to strengthen and he kept saying it would not hit Texas and that it was a Mexico storm, he was right. He nevr said central florida. He said rain in central florida which is reasonable.
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Question:

Isn't this a best-case scenario for the 2010 season?

What I mean is, the storm is expected to spend a lot of time over water and only get to TS strength.

Doesn't that churn-up cooler waters and reduce the danger in August and September?

Someone a few weeks ago said each day without a storm is a blessing, but I'm kinda of the belief that a lot of weaker storms are better than a monster in September.

In a "spread-out the ACE throughout the 2010 season" sense.

Does that make any sense? Any thoughts on this?
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Bonnie will come straight to louisiana. I hope!
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98L at 2PM should be given the higher end of the red shading percentage (80%+).
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Intensity Forecasts are not that great...i seldommly see them being right 3 and 4 days out....the best thing to do is to watch and wait...and be ready
Member Since: August 29, 2006 Posts: 22 Comments: 1342
Oh yay I'm in the cone.
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Quoting chrisdscane:
yo miamihuricanes 09 ur in miami right

the understatment of the day lol commonsense people lol sry i had to call you out on it
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Quoting chrisdscane:
yo miamihuricanes 09 ur in miami right
Yep.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
i have a feeling after recon they'll upgrade to bonnie....
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yo miamihuricanes 09 ur in miami right
Member Since: July 21, 2010 Posts: 0 Comments: 1089
Quoting Stormchaser2007:


Cat 3?

Completely unrealistic.

With those upper level winds? Exactly. But hey, what would this blog be without the drama?
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Quoting whs2012:
It's so funny how the blog calmed down after the track shifted to TX/LA, lol

no, the Katrina comparisons have been non stop. Tommorow there will non stop Ike or Rita comparisons.
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692. IKE
Quoting whs2012:
It's so funny how the blog calmed down after the track shifted to TX/LA, lol


I just shipped 2 boxes of depressant meds to WU bloggers in and around Miami. Should be arriving about 2 EDST.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
691. xcool
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Quoting chrisdscane:



ya ik i mean well know for sure were the center is
We'll have the 18z runs with new data too and so on and so forth.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
689. A4Guy
Quoting hydrus:
The increase in forward speed I agree with. The forecast as far as strength goes I disagree with. I think there will be a hurricane at some point.


considering the nhc mets have PHDs and you don't…I'll go with their fcst. Thanks, though. : )
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Quoting MiamiHurricanes09:
Doubt it, just a small shift to the right is what I'm expecting at 5PM, not that far north though.


Stop this shift to the right stuff!! That's gonna put it right over my newly purchased house! lol
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Quoting MiamiHurricanes09:
The 5PM will be the most accurate of all.



ya ik i mean well know for sure were the center is
Member Since: July 21, 2010 Posts: 0 Comments: 1089
Quoting Seamule1:
COC 22.0 N 74/2 W

convections starting to build around it...

cat three through the keys...

imho


Cat 3?

Completely unrealistic.

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Even if the cone stays south, Dade and Broward can expect lots and lots of rain - my garden will be happy!
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681. Jax82
You really have to trust the steering layers. Those who are saying the storm is going to Miami/FLL are way too north with their guess. I say guess because who knows what will happen (look at 98L forming out of nowhere) but looking at the models and steering layers we have to go with what data we have now. Hopefully the storm stays weak will be just a rain maker for south FL, they need it.
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Really? 3 1/2 days time is apparently all there is left of TD3? I mean, that's when it's projected to hit land. And max winds of 50mph? Something seems off, way off. Are they waiting for the models to get a better grip of TD3?
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COC 22.0 N 74/2 W

convections starting to build around it...

cat three through the keys...

imho
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Quoting Jeff9641:


Reported. So poof you will go!!!!!

I am now a JEFFCASTER, anything he says I go with. He has been right about two differnt tropical systems. The self stroking is geting annoyng though imo.
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OIL due to spin will be a huge problem for LA
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Quoting MiamiHurricanes09:
Doubt it, just a small shift to the right is what I'm expecting at 5PM, not that far north though.


Yeah. I'm guessing the TS watch for North of Dade County is in case this thing wants to intensify moderately.
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Quoting chrisdscane:

so the 2pm advisory is the more accurate one
The 5PM will be the most accurate of all.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting whs2012:
CONES NOW POSTED ON NHC SITE!
..

OH MY GOD NOOOOOOOOOOOOOO!!!!!!!!
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Looking at post# 644... One thing standing out to me is the HWRF model and its track... almost spot-on as to its current location.
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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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