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TROPICAL STORM GABRIELLE DISCUSSION NUMBER  17
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT SEP 15 2001

SHIPS DHER AND OZQP2 REPORTED 44 AND 43 KT NORTHWEST OF THE CENTER
AT 18Z...SO THE MAXIMUM INTENSITY IS RAISED TO 45 KT.  THAT BEING
SAID...GABRIELLE STILL DOESN'T APPEAR TO BE VERY TROPICAL.  WHILE
CONVECTION IS CLOSER TO THE CENTER THAN EARLIER...THE NEAREST
CONVECTION IS STILL ABOUT 75 NM FROM THE CENTER AND LOOKS LIKE
IT HAS AS MUCH TO DO WITH A FRONTAL SYSTEM AS IT DOES WITH
GABRIELLE.  SAB HAS CLASSIFIED THE SYSTEM AS EXTRATROPICAL...WHILE
TAFB IS CALLING IT SUBTROPICAL.  THE SYSTEM WILL STILL BE
CONSIDERED A TROPICAL CYCLONE UNTIL THERE IS CLEAR EVIDENCE THAT
IT HAS MERGED WITH THE FRONTAL ZONE.
 
GABRIELLE HAS ACCELERATED TO 055/13...AND ONCE AGAIN THE SHORT-
TERM MOTION MAY BE EVEN FASTER.  THE STORM IS NOW EMBEDDED IN THE
WESTERLIES AND SHOULD CONTINUE A GENERAL EAST-NORTHEAST TO NORTHEAST
MOTION THROUGH THE FORECAST PERIOD.  NHC HURRICANE GUIDANCE IS IN
GOOD AGREEMENT WITH THIS SCENARIO...AND THE FORECAST TRACK IS DOWN
THE MIDDLE OF THE GUIDANCE.  THE TRACK IS JUST A LITTLE TO THE NORTH
AND FASTER THAN THE PREVIOUS FORECAST.
 
THERE ARE STILL SEVERAL POSSIBILITIES IN REGARDS TO THE INTENSITY
FORECAST.  THE FIRST...RE-INTENSIFICATION AS A TROPICAL CYCLONE...
APPEARS UNLIKELY DUE TO THE BAROCLINIC ENVIRONMENT THE STORM IS
NOW EMBEDDED IN.  THE SECOND...RE-INTENSIFICATION AS A HYBRID
CYCLONE...IS POSSIBLE IN LIGHT OF THE SLIGHTLY IMPROVED CONVECTIVE
ORGANIZATION CAUSED BY INTERACTION WITH THE FRONTAL ZONE.  THE
THIRD POSSIBILITY IS EXTRATROPICAL TRANSITION...ALTHOUGH IT IS
NOTABLE THAT NONE OF THE GLOBAL MODELS SHOW MUCH STRENGTHENING
OF GABRIELLE AS A NON-TROPICAL LOW.  THE INTENSITY FORECAST
IS A COMBINATION OF THE SECOND AND THIRD POSSIBILITIES...CALLING
FOR SLIGHT STRENGTHENING FOLLOWED BY EXTRATROPICAL TRANSITION AT
72 HR.  GABRIELLE COULD BECOME EXTRATROPICAL EARLIER IF THE
CONVECTION DOES NOT PERSIST.
 
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     15/2100Z 30.1N  78.3W    45 KTS
12HR VT     16/0600Z 31.2N  76.4W    45 KTS
24HR VT     16/1800Z 32.6N  73.9W    45 KTS
36HR VT     17/0600Z 34.1N  71.0W    50 KTS
48HR VT     17/1800Z 36.0N  67.5W    50 KTS
72HR VT     18/1800Z 39.5N  61.0W    50 KTS...EXTRATROPICAL
 
 
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