HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   2
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED OCT 06 1999
 
THE LATEST SSM/I PASS FROM THE DMSP SATELLITE SUPPLIED BY THE NAVAL
RESEARCH LABORATORY IN MONTEREY CALIFORNIA SHOWS SUGGESTS THAT THE
CENTER OF TROPICAL DEPRESSION TWELVE IS A BIT FURTHER NORTH THAN
EARLIER ESTIMATES...MULTICHANNEL GOES-8 IMAGERY ALSO SUPPORTS THIS.
AS ALWAYS...ONE MUST BE CAUTIOUS WHEN USING IR-BASED IMAGERY TO RE-
POSITION SYSTEM CENTERS AT NIGHT.  THE 06Z POSITION HAS BEEN NUDGED
NORTHWARD HOWEVER...WE WILL WAIT FOR VISIBLE IMAGERY BEFORE MAKING
FURTHER ADJUSTMENTS. IT WOULD NOT BE SURPRISING IF THE CENTER NEEDS
TO BE ADJUSTED FURTHER NORTH ON THE NEXT PACKAGE.

THE INITIAL MOTION ESTIMATE IS 290/07 KNOTS. THE DEPRESSION IS ON
THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE WITH A TROUGH TO THE
NORTH AND WEST...PER WATER VAPOR IMAGERY.  THIS TROUGH MAY INDUCE
A MORE NORTHWESTERLY TRACK IN THE SHORT TERM BUT THE GLOBAL MODELS
DEVELOP A RIDGE OVER THE WESTERN ATLANTIC DURING THE NEXT FEW
DAYS.   THIS MAY TURN THE TROPICAL CYCLONE BACK TO A MORE WEST-
NORTHWEST HEADING BY 72 HOURS.  THIS SCENARIO WOULD MINIMIZE THE
THREAT TO THE LESSER ANTILLES.  THE OFFICIAL FORECAST TRACK 
IS ADJUSTED TO THE RIGHT OF THE PREVIOUS ADVISORY AND IS IN GOOD
AGREEMENT WITH BAMM AND A98E...ALTHOUGH SLIGHTLY FASTER. 

THE CENTER OF DEPRESSION TWELVE IS ON THE WESTERN EDGE OF THE DEEP
CONVECTION...WHICH IS RATHER LINEAR IN NATURE.  SATELLITE IMAGERY
AND CLOUD DRIFT WINDS FROM CIMSS/UNIVERSITY OF WISCONSIN SHOW THAT
THE SYSTEM IS EXPERIENCING SOME SOUTHERLY SHEAR. THE INITIAL
INTENSITY WILL BE HELD AT 30 KNOTS FOR THIS ADVISORY. THE
STATISTICAL HURRICANE INTENSITY PREDICTION SCHEME...SHIPS...SHOWS
A GRADUAL STRENGTHENING TREND SIMILAR TO THE PREVIOUS PACKAGE.
THE OFFICIAL FORECAST BRINGS THE SYSTEM TO TROPICAL STORM STRENGTH
IN 12 HOURS OR SO. HOWEVER...SOUTHWESTERLY SHEAR AHEAD OF THE
CYCLONE COULD INHIBIT STRENGTHENING.
 
GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     06/0900Z 15.2N  45.8W    30 KTS
12HR VT     06/1800Z 15.8N  46.9W    35 KTS
24HR VT     07/0600Z 16.5N  47.8W    40 KTS
36HR VT     07/1800Z 17.2N  48.7W    45 KTS
48HR VT     08/0600Z 18.5N  50.0W    50 KTS
72HR VT     09/0600Z 19.5N  52.0W    60 KTS
 
 
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