HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL DEPRESSION TWELVE DISCUSSION NUMBER   8
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT THU OCT 07 1999
 
CONVECTION HAS DECREASED WITH TROPICAL DEPRESSION TWELVE DURING THE
AFTERNOON...LEAVING AN EXPOSED LOW CLOUD SWIRL WITH WIDELY SCATTERED
CONVECTION WELL NORTHEAST AND SOUTHEAST OF THE CENTER. SATELLITE
INTENSITY ESTIMATES FROM TAFB AND SAB ARE 30 KT...SO THAT IS THE
INITIAL INTENSITY.

THE INITIAL MOTION IS 300/4. THERE IS LITTLE CHANGE IN EITHER THE
SYNOPTIC PATTERN OR THE FORECAST REASONING FROM THE PREVIOUS
PACKAGE. THE CYCLONE SHOULD CONTINUE SLOWLY WEST-NORTHWEST UNDER A
WEAKENED SUBTROPICAL RIDGE FOR 24 TO 36 HOURS...FOLLOWED BY A
GRADUAL INCREASE IN FORWARD SPEED. THE OFFICIAL FORECAST TRACK IS
LITTLE CHANGED FROM THE PREVIOUS PACKAGE.

WATER VAPOR IMAGERY INDICATES THAT WESTERLY FLOW ASSOCIATED WITH THE
UPPER LEVEL LOW/TROUGH NORTH OF THE CYCLONE CONTINUES TO SHEAR THE
DEPRESSION. THE AVN AND NOGAPS MODELS INDICATE THE TROUGH WILL
WEAKEN AND MOVE EASTWARD AFTER 12-24 HOURS. THIS IS NOT SUPPORTED BY
THE IMAGERY...WHICH SUGGESTS THE TROUGH IS STILL DIGGING SOUTH
TOWARD THE CYCLONE. THE INTENSITY FORECAST DELAYS INTENSIFICATION
EVEN MORE THAN PREVIOUSLY IN ANTICIPATION THAT THE SHEAR WILL NOT
DECREASE AS QUICKLY AS EARLIER FORECAST. EVEN THOUGH THE CYCLONE HAS
A LARGE CIRCULATION...THE ENVIRONMENT MAY STAY HOSTILE LONG ENOUGH
FOR IT TO WEAKEN OR DISSIPATE BEFORE THE SHEAR RELAXES.
 
BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     07/2100Z 16.1N  47.3W    30 KTS
12HR VT     08/0600Z 16.3N  47.6W    30 KTS
24HR VT     08/1800Z 16.6N  48.1W    30 KTS
36HR VT     09/0600Z 16.9N  48.6W    30 KTS
48HR VT     09/1800Z 17.5N  49.5W    35 KTS
72HR VT     10/1800Z 18.5N  52.0W    45 KTS
 
 
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