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#4389 (Received by flhurricane at: 5:22 AM 12.Aug.2004) TCDAT2 TROPICAL STORM BONNIE DISCUSSION NUMBER 17 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU AUG 12 2004 THE STRUCTURAL CHANGES MENTIONED EARLIER HAVE CONTINUED LEAVING THE MAXIMUM WINDS IN A BAND OF CONVECTION AWAY FROM THE CENTER. THE SYSTEM CONTINUES TO BE VERTICALLY SHEARED. SO FAR...THE LATEST RECONNAISSANCE FLIGHT HAS REPORTED A CENTRAL PRESSURE OF 1010 MB AND MAXIMUM SURFACE WINDS OF 37 KT. ON THE OTHER HAND...SATELLITE INTENSITY ESTIMATES ARE 55 KT FROM TAFB AND 45 KT FROM SAB AND AFWA...SUGGESTING THE AIRCRAFT MIGHT NOT HAVE SAMPLED THE STRONGEST WINDS. THE INITIAL INTENSITY IS DECREASED TO 45 KT. BONNIE NOW APPEARS TO BE ACCELERATING TOWARD THE NORTHEAST AS HAS BEEN ANTICIPATED. THE INITIAL MOTION IS 045/14. THE TRACK FORECAST IS STRAIGHTFORWARD. BONNIE IS EMBEDDED IN SOUTHWESTELY FLOW ASSOCIATED WITH AN UNSEASONABLY STRONG DEEP LAYER TROUGH OVER THE CENTRAL UNITED STATES. THE CYCLONE SHOULD CONTINUE TO ACCELERATE NORTHEASTWARD ON THE EAST SIDE OF THE TROUGH...MAKING LANDFALL OVER THE FLORIDA PANHANDLE THURSDAY AFTERNOON AND THEN MOVING THROUGH THE EASTERN UNITED STATES. ALL TRACK GUIDANCE AGREES WITH THIS SCENARIO...AND THE TRACK FORECAST IS IN AGREEMENT WITH THE CONCENSUS...WHICH IS A LITTLE TO THE LEFT OF THE PREVIOUS OFFICIAL FORECAST. THE STEADILY INCREASING VERTICAL SHEAR SUGGESTS THAT THE WINDOW OF OPPORTUNITY FOR STRENGTHENING IS OVER. HOWEVER...THE CYCLONE HAS JUST GENERATED BURSTS OF CONVECTION TO THE EAST AND SOUTHEAST OF THE CENTER. EVEN SO IT WILL NOT BE ABLE TO DEEPEN ENOUGH TO REACH HURRICANE INTENSITY BEFORE LANDFALL. THE INTENSITY FORECAST WILL KEEP THE SYSTEM INVARIANT AT 45 KTS UNTIL LANDFALL...BUT SOME FLUCTUATIONS ARE POSSIBLE. AFTER LANDFALL... BONNIE SHOULD WEAKEN AND BECOME EXTRATROPICAL. BASED UPON THE ABOVE THE HURRICANE WARNINGS AND WATCHES HAVE BEEN DISCONTINUED. FORECASTER JARVINEN FORECAST POSITIONS AND MAX WINDS INITIAL 12/0900Z 28.4N 87.5W 45 KT 12HR VT 12/1800Z 30.4N 85.6W 45 KT...INLAND 24HR VT 13/0600Z 35.1N 81.1W 40 KT...INLAND 36HR VT 13/1800Z 40.8N 76.5W 35 KT...INLAND...EXTRATROPICAL 48HR VT 14/0600Z 47.0N 72.0W 35 KT...INLAND...EXTRATROPICAL 72HR VT 15/0600Z 56.2N 59.2W 35 KT...INLAND...EXTRATROPICAL |