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#44620 (Received by flhurricane at: 11:00 PM 07.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT WED SEP 07 2005 SATELLITE IMAGERY INDICATES THAT OPHELIA REMAINS SOMEWHAT SHEARED THIS EVENING...WITH BURSTS OF CONVECTION IN THE WESTERN QUADRANT. THE LATEST WSR-88D IMAGERY FROM MELBOURNE SHOWS A NEW BURST ABOUT 25-30 N MI WNW OF THE CENTER...AND THAT THE EAST SIDE OF THE STORM APPEARS SOMEWHAT DRY. AN AIR FORCE RESERVE HURRICANE HUNTER HAS EXTRAPOLATED CENTRAL PRESSURES OF 994 AND 995 MB...WITH MAXIMUM FLIGHT-LEVEL WINDS AT 850 MB OF 54 KT. THIS IS IN GOOD AGREEMENT WITH THE DOPPLER WINDS FROM MELBOURNE...AND BASED ON THESE THE INITIAL INTENSITY REMAINS 45 KT. THE INITIAL MOTION IS STATIONARY. OPHELIA IS SOUTH OF A STRONG LOW-LEVEL RIDGE...AND BETWEEN SEGMENTS OF THE MID-LEVEL SUBTROPICAL RIDGE. THIS IS PRODUCING A WEAK STEERING ENVIRONMENT. THE GFS... UKMET...AND CANADIAN MODELS FORECAST THE WESTERLIES TO SINK SOUTHWARD AND STEER OPHELIA TO THE NORTHEAST AND EAST...WHILE THE ECMWF CONTINUES TO CALL FOR A WESTWARD MOTION ACROSS THE FLORIDA PENINSULA INTO THE GULF OF MEXICO. THE NOGAPS...GFDL...AND GFDN FORECAST SLOW AND LOOPING MOTION JUST OFF THE NORTHEAST FLORIDA AND GEORGIA COASTS FOR THE NEXT 5 DAYS. GIVEN THE MODEL SPREAD...THE FORECAST WILL CONTINUE TO CALL FOR A SLOW MOTION...WITH THE NEW TRACK SIMILAR TO AND JUST A LITTLE EAST OF THE PREVIOUS TRACK. THE TRACK FORECAST REMAINS LOW CONFIDENCE. THE INTENSITY FORECAST REMAINS PROBLEMATIC. SOME SOUTHEASTERLY SHEAR CONTINUES...AND THE SHIPS MODEL FORECAST THAT MODERATE SHEAR WILL PERSIST FOR MUCH OF THE NEXT 5 DAYS. INDEED...IF THE STORM GETS NORTH OF 30N THE SHEAR IS LIKELY TO SIGNIFICANTLY INCREASE. IN ADDITION...WATER VAPOR SHOWS MID/UPPER-LEVEL DRY AIR IMPINGING ON THE STORM FROM THE NORTHWEST AND SOUTHEAST. THE GFDL BRINGS OPHELIA TO 84 KT...WHILE THE SHIPS MODEL IS MORE CONSERVATIVE AT 64 KT. THE INTENSITY FORECAST WILL BE SLIGHTLY ABOVE THE SHIPS MODEL AND BRING OPHELIA TO HURRICANE STRENGTH IN 48 HR. THIS IS ALSO A LOW CONFIDENCE FORECAST. ALL INTERESTS IN NORTH FLORIDA AND SOUTHEASTERN GEORGIA SHOULD MONITOR THE PROGRESS OF THIS DEVELOPING CYCLONE. SHOULD OPHELIA STRENGTHEN FASTER AND MOVE CLOSER TO THE COAST THAN CURRENTLY FORECAST...A HURRICANE WATCH MAY BE NECESSARY SOMETIME ON THURSDAY. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 08/0300Z 28.9N 79.3W 45 KT 12HR VT 08/1200Z 29.1N 79.5W 50 KT 24HR VT 09/0000Z 29.4N 79.7W 55 KT 36HR VT 09/1200Z 29.8N 79.8W 60 KT 48HR VT 10/0000Z 30.3N 79.6W 65 KT 72HR VT 11/0000Z 30.5N 79.0W 65 KT 96HR VT 12/0000Z 30.5N 78.5W 70 KT 120HR VT 13/0000Z 30.5N 78.5W 70 KT |