ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM 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 $$ NNNN
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Page last modified: Wednesday, 11-Aug-2004 14:32:39 UTC