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