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TROPICAL STORM GABRIELLE DISCUSSION NUMBER  21
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN SEP 16 2001
 
GABRIELLE HAS CONTINUED TO DEVELOP DEEP CONVECTION ON THE NORTH SIDE 
OF THE RAGGED EXPOSED LOW-LEVEL CIRCULATION TODAY.  THE INITIAL 
INTENSITY IS MAINTAINED AT 55 KT UNTIL NOAA RECON AIRCRAFT REPORT 
BACK LATER THIS AFTERNOON AND EVENING ON THE EXACT INNER-CORE 
CONDITIONS.  SATELLITE INTENSITY ESTIMATES VARY FROM 35 KT FROM SAB 
TO 50-55 KT FROM KGWC FOR SUBTROPICAL AND EXTRATROPICAL CYCLONES... 
RESPECTIVELY.
 
THE INITIAL MOTION ESTIMATE IS 070/14. GABRIELLE HAS MADE A SLIGHT 
JOG TO THE EAST DURING THE PAST 6 HOURS.  HOWEVER...IF A SIGNIFICANT 
LOW-LEVEL CIRCULATION IS GOING TO PERSIST...IT WILL LIKELY DO SO 
CLOSER TO THE DEEP CONVECTION. AS SUCH...THE OFFICIAL FORECAST TRACK 
IS ONLY SLIGHTLY TO THE RIGHT OF THE PREVIOUS FORECAST TRACK. THE 
NHC MODEL GUIDANCE CONTINUES TO REMAIN IN EXCELLENT AGREEMENT ON 
TURNING GABRIELLE BACK TO THE NORTHEAST BY 12 HOURS...AND THEN 
CONTINUING ON A GENERAL NORTHEASTWARD TRACK THROUGHOUT THE REMAINDER 
OF THE FORECAST PERIOD.  THE OFFICIAL FORECAST TRACK IS CLOSE TO A 
BLEND OF THE AVN AND GFDL MODELS. THE UKMET MODEL IS NOW THE LEFT- 
MOST MODEL OF THE ENTIRE GUIDANCE SUITE AND TAKES GABRIELLE RAPIDLY 
ACROSS NEWFOUNDLAND IN ABOUT 48 TO 60 HOURS.  THIS SEEMS A LITTLE 
EXCESSIVE BASED ON THE MORE ZONAL MID- TO UPPER-LEVEL FLOW THAT IS 
FORECAST TO DEVELOP ACROSS THE NORTHEAST U.S. AND EASTERN CANADA BY 
ALL OF THE GLOBAL MODELS.
 
AS MENTIONED IN THE PREVIOUS FORECAST DISCUSSION...IT IS QUITE 
POSSIBLE THAT GABRIELLE MAY STAY ON THE WARM SIDE OF THE FRONTAL 
BOUNDARY AND REMAIN MORE TROPICAL-LIKE FOR THE NEXT 24 TO 36 
HOURS...UNTIL THE NEXT SHORTWAVE TROUGH FINALLY PICKS UP THE SYSTEM 
AND MAKES GABRIELLE MORE BAROCLINIC.  WHILE DEEP CONVECTION HAS 
PERSISTED NORTH OF THE CENTER TODAY...LITTLE IF ANY ADDITIONAL 
STRENGTHENING WILL OCCUR UNLESS DEEP CONVECTION DEVELOPS DIRECTLY 
OVER THE CENTER.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     16/2100Z 32.3N  72.6W    55 KTS...BECOMING EXTRATROPICAL
12HR VT     17/0600Z 33.0N  70.0W    50 KTS...EXTRATROPICAL
24HR VT     17/1800Z 34.5N  66.5W    50 KTS...EXTRATROPICAL
36HR VT     18/0600Z 36.0N  63.5W    50 KTS...EXTRATROPICAL
48HR VT     18/1800Z 37.5N  60.5W    50 KTS...EXTRATROPICAL
72HR VT     19/1800Z 40.0N  56.0W    45 KTS...EXTRATROPICAL
 
 
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