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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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