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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Max Mayfield stating that 97L will not be able to go anywhere north of southern Florida because of a ridge to the north regardless of how strong it is.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Developing TD in BOC..
Member Since: July 8, 2005 Posts: 259 Comments: 24575
Quoting StadiumEffect:
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.
The only island consider "good size islands are Puerto Rico, Hispaniola, Cuba, the Bahamas don't make any different to a system, to small.
Member Since: Posts: Comments:
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.
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Quoting extreme236:
They put it at 75.0 west, which doesn't seem correct to me.
Me either.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Ameister12:
Can't wait to see the track cone.


You can pretty well figure it out from the Tropical Storm Force Wind Speed Probabilities chart at the nhc site
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Can't find any data from recon..
Member Since: July 8, 2005 Posts: 259 Comments: 24575
They put it at 75.0 west, which doesn't seem correct to me.
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they not even update the 98L... not recon to that one...?
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Quoting Ameister12:
Can't wait to see the track cone.


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Quoting Jeff9641:
The center is continuing to build north. look at the visible below. IMAO......


http://www.wunderground.com/tropical/tracking/at201097_sat.html


Northcaster
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556. xcool
RECONNAISSANCE PLANE EN ROUTE...
???
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the UUL over 25n 65w appears to be pushing on the new depression#3 keeping it moveing more west ....and may cause it to move into the western gulf over time ...
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They're calling it a depression , but I wouldn't be surprised if the next flight shows otherwise .
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Can't wait to see the track cone.
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75.0 WEST.

?
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Been lurker here since '04 and have posted a few times. Always come here for accurate information. I'm in Clearwater. Is it safe to say we are not going to see much from this? Looks like there would have to be a major shift. TIA!
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Quoting RitaEvac:
BTW, 98L looks better


It certainly does.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
Quoting Jeff9641:
The center is continuing to build north. look at the visible below. IMAO......


http://www.wunderground.com/tropical/tracking/at201097_sat.html


This is not coming to Central Florida.....
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Accuweather says it has been a depression for some time now, TD3 should become a storm and possible cat1 hurricane before its final landing in Louisiana or Texas next week? Right now sheer is keeping it from being a stronger storm.
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547. 900MB
Quoting AllStar17:
I have a hard time believing it is only going to get to 50 mph.


Agreed!
Member Since: June 11, 2006 Posts: 0 Comments: 684
Remember, intensity is hard to predict. It could very well be stronger than 50 mph.
Member Since: July 8, 2005 Posts: 259 Comments: 24575
hmm,if it stays off land from its position here to a possible landfall in louisanna or there abouts "3 days from now a landfall"?. It would have to move around 20 mph right through, that might be a bit suspicious to me i don't what u guys think on that.
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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
Member Since: September 2, 2007 Posts: 179 Comments: 20448
BTW, 98L looks better
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542. xcool
TD IN GOM HMM
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Lets make sure the 11am nhc report is posted a thousand times
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Quoting jasoniscoolman2010x:
HERE IT IS..

You gave up on this yesterday...said RIP and now here you are all hyped up again. That is cool if you are but please dont start the false forecasting again....have a great day
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wifey just called me hyperventilating breathing into paper bag while watching WSVN gloom and doom people LOL
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They only take it up to 50mph lol

Why are those people calling for a major hurricane?
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Member Since: September 30, 2007 Posts: 9 Comments: 15977
Its placement and track reminds me of ol Rita, TRACK PEOPLE, not intensity
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Looks like they are going to let the plane make the call.
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I have a hard time believing it is only going to get to 50 mph.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
529. IKE
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.
Member Since: Posts: Comments:


Not good, not good at all.
Member Since: September 2, 2006 Posts: 110 Comments: 6878
what the ... the discussion is from 00 PM AST SAT SEP 26 2009
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00
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
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Quoting whs2012:


000
ABNT20 KNHC 221224
TWOAT
SPECIAL TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
825 AM EDT THU JUL 22 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SPECIAL OUTLOOK ISSUED TO UPDATE THE DISTURBANCE IN THE SOUTHEAST
BAHAMAS.

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.

AN AREA OF SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A BROAD AREA OF
LOW PRESSURE IN THE BAY OF CAMPECHE CONTINUES TO SHOW SIGNS OF
ORGANIZATION. ENVIRONMENTAL CONDITIONS APPEAR TO BE CONDUCIVE FOR
SOME DEVELOPMENT OF THE LOW AS IT MOVES WESTWARD OR WEST-
NORTHWESTWARD AT 10 TO 15 MPH. THERE IS A MEDIUM CHANCE...50
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE BEFORE IT
REACHES THE COAST OF MEXICO IN A DAY OR TWO.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER AVILA/ROBERTS


That's 4 hours old
Member Since: October 30, 2007 Posts: 0 Comments: 270
ahhhh nope its td3!!!
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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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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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