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#367855 (Received by flhurricane at: 10:47 AM 11.Aug.2010) TCDAT5 TROPICAL DEPRESSION FIVE DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052010 1100 AM EDT WED AUG 11 2010 VISIBLE SATELLITE IMAGERY AND BUOY REPORTS INDICATE THAT THE CIRCULATION OF THE DEPRESSION REMAINS VERY LARGE AND ELONGATED. BANDS OF SHOWERS AND THUNDERSTORMS ARE LOCATED AROUND THE PERIPHERY OF THE DEPRESSION BUT REMAIN LIMITED NEAR THE CENTER. IT APPEARS THAT THE CENTER...SUCH AS IT IS...REFORMED OVERNIGHT TO THE NORTHWEST OF THE EARLIER ESTIMATES. A MEAN CENTER OF THE OVERALL SYSTEM RATHER THAN A WIND CENTER WAS USED FOR THE ADVISORY POSITION. THE INITIAL INTENSITY WAS LOWERED TO 25 KT THIS MORNING...AND THESE WINDS ARE LIMITED TO A FEW RAIN BANDS IN THE EASTERN SEMICIRCLE. DUE TO THE POOR ORGANIZATION OF THE SYSTEM...THE INITIAL MOTION IS HIGHLY UNCERTAIN. THE BEST ESTIMATE IS 305/10. THE TRACK GUIDANCE HAS NOT CHANGED THIS MORNING AND CONTINUES TO INDICATE A NORTHWEST MOTION AROUND THE SOUTHWEST SIDE OF A MID- TO UPPER-LEVEL RIDGE LOCATED NEAR THE SOUTHEASTERN UNITED STATES COAST. THIS MOTION IS EXPECTED TO CONTINUE UNTIL LANDFALL IN ABOUT 24 HOURS. THEREAFTER... THE RIDGE IS FORECAST TO SHIFT SOUTH AND WEAKEN...WHICH IS EXPECTED TO CAUSE THE DEPRESSION TO SLOW DOWN AND TURN TOWARD THE NORTH AND THEN NORTHEAST. THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY...BUT IS A LITTLE FASTER DUE TO THE UPDATED INITIAL POSITION. ALTHOUGH THE UPPER-LEVEL PATTERN IS FORECAST TO GRADUALLY BECOME MORE CONDUCIVE FOR STRENGTHENING...THE SPRAWLING STRUCTURE OF THE DEPRESSION SUGGESTS THAT ANY INTENSIFICATION WOULD BE SLOW. IN ADDITION...THE SYSTEM SHOULD NOW HAVE LESS TIME OVER WATER THAN PREVIOUSLY EXPECTED. AS A RESULT...THE NEW INTENSITY FORECAST IS LOWERED FROM THE PREVIOUS ADVISORY...BUT IS STILL A LITTLE ABOVE THE SHIPS/LGEM GUIDANCE. ALTHOUGH THE GFDL AND HWRF ARE MORE AGGRESSIVE...THE INITIALIZATION OF THESE MODELS IS UNLIKELY TO ACCURATELY REFLECT THE CURRENT CYCLONE STRUCTURE. ONE SHOULD NOT FOCUS ON THE EXACT TRACK OF WEAK TROPICAL CYCLONES SINCE MOST OF THE ASSOCIATED WEATHER IS TYPICALLY WELL REMOVED FROM THE CENTER. THIS IS CERTAINLY THE CASE WITH THIS DEPRESSION. IF THE DEPRESSION SLOWS DOWN AS FORECAST AFTER LANDFALL...HEAVY RAINFALL WOULD BECOME THE PRIMARY THREAT. FORECAST POSITIONS AND MAX WINDS INITIAL 11/1500Z 27.8N 86.8W 25 KT 12HR VT 12/0000Z 28.6N 88.1W 30 KT 24HR VT 12/1200Z 29.6N 89.4W 35 KT 36HR VT 13/0000Z 30.4N 90.1W 30 KT...INLAND 48HR VT 13/1200Z 31.2N 90.2W 25 KT...INLAND 72HR VT 14/1200Z 32.6N 89.3W 20 KT...POST-TROP/REMNT LOW 96HR VT 15/1200Z 34.0N 87.5W 20 KT...POST-TROP/REMNT LOW 120HR VT 16/1200Z...DISSIPATED $$ FORECASTER BROWN/CANGIALOSI |