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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Not to brag but when on Tuesday everyone was calling this a Tropical Depression Im the one who said "Dont expect Depression status til Thursday" Anyway this baby is starting to blow up fast!
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ITS TD NUMBER3
Member Since: July 21, 2010 Posts: 0 Comments: 1091


Member Since: January 30, 2010 Posts: 0 Comments: 3259
000
WTNT33 KNHC 221459
TCPAT3
BULLETIN
TROPICAL DEPRESSION THREE ADVISORY NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032010
1100 AM EDT THU JUL 22 2010

...TROPICAL DEPRESSION FORMS IN THE BAHAMAS...AIR FORCE
RECONNAISSANCE PLANE EN ROUTE...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.9N 75.0W
ABOUT 265 MI...425 KM SE OF NASSAU
ABOUT 405 MI...655 KM ESE OF KEY LARGO FLORIDA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/HR
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 15 MPH...24 KM/HR
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A TROPICAL STORM WARNING
FOR THE CENTRAL AND NORTHWESTERN BAHAMAS.

A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE FLORIDA EAST COAST
FROM GOLDEN BEACH SOUTHWARD INCLUDING THE ENTIRE FLORIDA KEYS AND
FLORIDA BAY...AND ALONG THE WEST COAST OF FLORIDA NORTHWARD TO
BONITA BEACH.

A TROPICAL STORM WATCH HAS BEEN ISSUED FOR THE EAST COAST OF FLORIDA
FROM NORTH OF GOLDEN BEACH TO JUPITER INLET INCLUDING LAKE
OKEECHOBEE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* CENTRAL AND NORTHWESTERN BAHAMAS
* FOR THE FLORIDA EAST COAST FROM GOLDEN BEACH SOUTHWARD INCLUDING
THE ENTIRE FLORIDA KEYS AND FLORIDA BAY...AND ALONG THE WEST COAST
OF FLORIDA NORTHWARD TO BONITA BEACH

A TROPICAL STORM WATCH IN IN EFFECT FOR...
* THE EAST COAST OF FLORIDA NORTH OF GOLDEN BEACH TO JUPITER INLET
INCLUDING LAKE OKEECHOBEE

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 AM EDT...1500 UTC...THE CENTER OF NEWLY FORMED TROPICAL
DEPRESSION THREE WAS LOCATED NEAR LATITUDE 21.9 NORTH...LONGITUDE
75.0 WEST. THE DEPRESSION IS MOVING TOWARD THE WEST-NORTHWEST NEAR
15 MPH...24 KM/HR. THIS GENERAL MOTION WITH AN INCREASE IN FORWARD
SPEED IS EXPECTED DURING THE NEXT 48 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. THE DEPRESSION COULD BECOME A TROPICAL STORM LATER TODAY.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB...29.77 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...WINDS NEAR TROPICAL STORM FORCE ARE ALREADY AFFECTING
PORTIONS OF THE SOUTHEASTERN BAHAMAS. TROPICAL STORM CONDITIONS
WILL GRADUALLY SPREAD OVER THE CENTRAL AND NORTHWESTERN BAHAMAS
TONIGHT AND FRIDAY. WEATHER CONDITIONS WILL BEGIN TO DETERIORATE ON
THE FLORIDA COAST AND FLORIDA KEYS WITHIN THE WARNING AREA ON
FRIDAY.

RAINFALL...THE DEPRESSION IS EXPECTED TO PRODUCE TOTAL RAIN
ACCUMULATIONS OF OF 2 TO 4 INCHES OVER SOUTH FLORIDA...WITH
POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 5 TO 6 INCHES. RAINFALL
AMOUNTS OF 3 TO 5 INCHES ARE EXPECTED OVER THE CENTRAL AND
NORTHWEST BAHAMAS...WITH POSSIBLE ISOLATED AMOUNTS OF 5 TO 7
INCHES.

STORM SURGE...STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 1 TO
2 FEET ABOVE GROUND LEVEL OVER PORTIONS OF THE BAHAMAS AND THE
FLORIDA KEYS.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...200 PM EDT.
NEXT COMPLETE ADVISORY...500 PM EDT.

$$
FORECASTER AVILA/ROBERTS
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Its up!
Member Since: May 16, 2010 Posts: 0 Comments: 1455
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515. 7544
td now no ts yet officail
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Its up.
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513. IKE
I don't see no update NHC!

*Makes another pot of coffee*

There it is....

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TD 3 on the graphic

No Bonnie just yet
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TD 3
Member Since: Posts: Comments:
509. MahFL
bah TD.....:(
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NHC now says TD#3Link
Member Since: October 30, 2007 Posts: 0 Comments: 270
Tropical depression at 11 am
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TD3 is on the map.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
yeah! TD3 now in nhc!
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Quoting BahaHurican:
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...
Right! I saw that post too and Katrina formed into a depression at 23.3 N and 75.5. It was a Cat1 Hurricane with 75/80 mph winds as it hit land.
Member Since: May 16, 2010 Posts: 0 Comments: 1455
Quoting DestinJeff:


Thats off look at the spiral bands location on RGB.

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Quoting extreme236:
Interesting to note, even though they are upgrading 97L to 03L...there was never a renumber.


I noticed that too
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I should train my dog to press the F5 key.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
497. 7544
its exploding now wow
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Cat 5 by Monday!
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Quoting sebastianflorida:
I guess it is taking longer to get the TWO out because their moms are making em put away their crayons before doing anything else.


No... I just saw a report that all the people refreshing took down the server
Member Since: July 1, 2005 Posts: 10 Comments: 1683
It's looking like Bonnie has arrived .
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no wonder their was a echo,lol
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Farewell red circle.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
Quoting hydrus:
97L is in the midst of all those good sized islands. Could this slow the organization?
None of the Bahamian islands are of any significant size that they would really affect a cyclone. Especially ones that aren't stationary or don't have a very slow forward speed.
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AHHHHHHHHHHHHHHHHHHHHHHHHHHHHH BLOG insanity people can we be calm and civilized lol
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Quoting Hurricanes101:
*F5..F5..F5..sips orange juice..pets the dog..changes channels..F5..F5..F5......

lol... i'm going to need physical therapy on my index finger by the end of season.
Member Since: June 21, 2010 Posts: 0 Comments: 61
Quoting tropicfreak:
AM I ON IGNORE???
NO, tropic. Just post what u wanted to say/ask again?
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.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
TS bonnie!!!!,I was yeeling it on the last blog
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Quoting tropicfreak:


Camille strength!

The recorded 221MPH gust was on Green Turtle Cay.

Most likely a tornado.

Scary sh!t though. By no means weak LOL
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That is one unfavorable looking Atlantic. 2010= year of the ULL's??? http://www.ssd.noaa.gov/goes/east/tatl/flash-wv.html
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Interesting to note, even though they are upgrading 97L to 03L...there was never a renumber.
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481. myway
Quoting jasoniscoolman2010x:
I AM STILL HITTING THE F5 FROM NHC PAGE..I DO NOT SEE IT YET. TROPICAL D. YET..


not 11 yet
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Quoting SWFLCruiser:
We're in a marina in Marathon for a little diving (haha); what should we expect from 97L/Bonnie?
drive away very fast not speeding of course and all will be ok I would cancell
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Not to brag but Im the one who said on Tuesday, "Dont expect this system to become a Depression til Thursday morning." Anyway now this baby is starting to get it's act together quickly.
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First time blogger here in nearly 4 years...

The longer the NHC waits means they may be adding last minute details to 11 am advisory.
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477. IKE
F5...F5.....attaches new keyboard.....F5....F5.....F5......F5......F5..........
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Shees! They must be wrestling with the intensity level. NHC usually sends out their products beofre now.
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Quoting jasoniscoolman2010x:
I AM STILL HITTING THE F5 FROM NHC PAGE..I DO NOT SEE IT YET. TROPICAL D. YET..


Same here.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
I guess it is taking longer to get the TWO out because their moms are making em put away their crayons before doing anything else.
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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.


I actually enjoy that they hype things up, lol.
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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: 21091

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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.