Tropical Storm BONNIE

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TROPICAL STORM BONNIE DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT WED AUG 11 2004
 
RECONNAISSANCE AND SATELLITE DATA...AND REPORTS FROM NOAA BUOY 42001
...INDICATE TROPICAL STORM BONNIE HAS BECOME MUCH BETTER ORGANIZED
AND HAS STRENGTHENED. BUOY 42001 LOCATED ABOUT 45 NMI NORTHEAST OF
THE CENTER REPORTED A 10-MINUTE AVERAGE WIND OF 41 KT WITH A GUST
TO 52 KT. GRADIENT WIND COMPUTATIONS USING A 10 MB PRESSURE
DIFFERENCE BETWEEN BONNIE AND BUOY 42001 INDICATE NEAR 50-KT WINDS
ARE POSSIBLE. THEREFORE...THE INTENSITY HAS BEEN CONSERVATIVELY
INCREASED TO 45 KT.

THE INITIAL MOTION ESTIMATE IS 025/05. IT APPEARS THAT BONNIE HAS
PASSED NORTH OF THE MID-LEVEL RIDGE AXIS THAT EXTENDS WESTWARD FROM
SOUTH FLORIDA AND IS COMING UNDER THE INFLUENCE OF AN APPROACHING
SHORTWAVE TROUGH LOCATED OVER THE SOUTHERN PLAINS. BONNIE IS
EXPECTED TO GRADUALLY ACCELERATE OVER THE NEXT 24 HOURS AND TURN
MORE NORTHEASTWARD LATER TODAY...IF IT HASN'T DONE SO ALREADY. THE
GLOBAL AND REGIONAL MODELS REMAIN IN GOOD AGREEMENT ON LANDFALL
OCCURRING THURSDAY MORNING IN THE FLORIDA PANHANDLE. THE MAIN
CONCERN IS THAT WITH THE MID-LEVEL WINDS FORECAST TO BECOME
SOUTHWEST OR WEST-SOUTHWESTERLY BY 24 HOURS...BONNIE COULD MAKE A
SHARP TURN MORE TOWARD THE EAST-NORTHEAST OR EAST JUST BEFORE
LANDFALL OCCURS. THIS WOULD BE TO THE RIGHT OF THE CURRENT FORECAST
TRACK AND THIS SCENARIO WILL BE CLOSELY EVALUATED FOR THE NEXT
ADVISORY. DUE TO THE UNCERTAINTY IN THE EXACT LOCATION AND
INTENSITY AT LANDFALL...A TROPICAL STORM WARNING AND A HURRICANE
WATCH HAVE BEEN ISSUED FOR THE PREVIOUS TROPICAL STROM WATCH AREA.

THE INTENSITY FORECAST REMAINS PROBLEMATIC WITH THE BURST OF DEEP
CONVECTION...TOPS AS COLD AS -83C...THAT HAS DEVELOPED OVER THE
CENTER THIS MORNING. IF RECON FINDS AN EYE OR EYEWALL FORMING LATER
THIS AFTERNOON...THEN IT IS POSSIBLE THAT BONNIE COULD BECOME A
HURRICANE BETWEEN THE 12 AND 24 HOUR TIME PERIODS...BEFORE
WEAKENING OCCURS DUE TO INCREASING WIND SHEAR JUST BEFORE LANDFALL.
FACTORS SUPPORTING POSSIBLE STRENGTHENING TO HURRICANE INTENSITY
ARE -- BETTER INNER-CORE WIND FIELD ORGANIZATION CURRENTLY
ONGOING...DEEP CONVECTION CURRENTLY OVER THE CENTER...LOW SHEAR
EXPECTED FOR THE NEXT 12 HOURS OR SO...AND BONNIE PASSING OVER A
WARMER GULF EDDY IN 12-18 HOURS DURING THE NOCTURNAL CONVECTIVE
MAXIMUM PERIOD TONIGHT AND TOMORROW MORNING.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1500Z 25.9N  90.3W    45 KT
 12HR VT     12/0000Z 27.4N  89.0W    55 KT
 24HR VT     12/1200Z 29.6N  86.5W    60 KT
 36HR VT     13/0000Z 32.3N  83.4W    45 KT...INLAND
 48HR VT     13/1200Z 36.0N  79.5W    30 KT...INLAND
 72HR VT     14/1200Z 45.5N  70.0W    30 KT...EXTRATROPICAL
 96HR VT     15/1200Z...ABSORBED BY FRONTAL SYSTEM
 
 
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