HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   3
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT WED OCT 06 1999
 
SATELLITE IMAGERY INDICATES THAT TROPICAL DEPRESSION TWELVE HAS
CHANGED LITTLE IN ORGANIZATION OVER THE PAST FEW HOURS...WITH THE
LOW LEVEL CENTER PARTIALLY EXPOSED TO THE WEST OF THE MAIN
CONVECTION. SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 35
KT AND 30 KT RESPECTIVELY. WITH THE SOMEWHAT RAGGED APPEARANCE OF
THE CONVECTION...THE INITIAL INTENSITY REMAINS AT 30 KT.

THE INITIAL MOTION IS 280/6. VISIBLE SATELLITE IMAGERY INDICATES A
LOW LEVEL RIDGE NORTH OF THE DEPRESSION...WITH WATER VAPOR IMAGERY
INDICATING A LARGE UPPER LEVEL TROUGH NORTH OF 20N BETWEEN 40W-50W.
LARGE SCALE AND NHC HURRICANE GUIDANCE RESPONDS TO THIS BY
INDICATING A WEST-NORTHWEST TO NORTHWEST MOTION THROUGH 72 HOURS.
THE OFFICIAL FORECAST REFLECTS THIS...BUT IS ALONG THE LEFT SIDE OF
THE GUIDANCE IN RESPONSE TO THE CURRENT MOTION. THE FORECAST TRACK
IS IN BEST AGREEMENT WITH THE BAMS.

ALTHOUGH CIRRUS CLOUD MOTIONS INDICATE AN ANTICYCLONE OVER THE
CONVECTION...THE SYSTEM HAS A SHEARED APPEARANCE. IT MAY BE THAT
SOUTHWESTERLY FLOW IS UNDERCUTTING THE ANTICYCLONE. THE AVN AND
NOGAPS INDICATE THAT A RIDGE OR ANTICYCLONE WILL BUILD ACROSS THE
TROPICAL ATLANTIC AND DECREASE THE SHEAR. HOWEVER...WATER VAPOR
IMAGERY SUGGESTS THE TROUGH NORTH OF THE CYCLONE IS STRONGER AND
FARTHER SOUTH THAN EITHER MODEL...WHICH MEANS IT MAY NOT DISSIPATE
AS QUICKLY AS THEY PREDICT. DUE TO THE GUIDANCE...THE INTENSITY
FORECAST IS UNCHANGED FROM THE PREVIOUS PACKAGE. HOWEVER...IF THE
TROUGH PERSISTS THE DEPRESSION SHOULD STRENGTHEN SLOWER THAN
CURRENTLY FORECAST.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     06/1500Z 15.2N  46.4W    30 KTS
12HR VT     07/0000Z 15.4N  47.3W    35 KTS
24HR VT     07/1200Z 15.9N  48.4W    40 KTS
36HR VT     08/0000Z 16.6N  49.6W    45 KTS
48HR VT     08/1200Z 17.5N  51.0W    50 KTS
72HR VT     09/1200Z 19.0N  53.0W    60 KTS
 
 
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