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| #44462 (Received by flhurricane at: 5:11 AM 07.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED SEP 07 2005 DATA FROM NOAA LAND-BASED DOPPLER RADARS AND A NOAA RECONNAISSANCE AIRCRAFT INDICATE OPHELIA HAS BECOME SLIGHTLY BETTER ORGANIZED... BUT IT STILL REMAINS A SHEARED TROPICAL CYCLONE. THE INTENSITY OF 35 KT IS BASED ON A BLEND OF SURFACE REPORTS OF 33 KT FROM DRIFTING BUOY 41542...LOCATED JUST NORTHEAST OF THE CENTER...AND DOPPLER RADAR VELOCITIES OF 36-44 KT BETWEEN 10000 FT AND 12000 FT. THE HIGHEST RECON WIND REPORT HAS BEEN 42 KT IN THE NORTHWEST QUADRANT. THE INITIAL MOTION IS 335/07...BASED ON THE LAST 3 RECON POSITIONS. THE TRACK FORECAST IS ANYTHING BUT STRAIGHTFORWARD. THE MAJORITY OF THE GLOBAL MODELS TAKE OPHELIA SLOWLY NORTHWESTWARD FOR 24 HOURS AND THEN GRADUALLY TURN THE CYCLONE NORTHEAST AND EASTWARD...AND MAKE A SMALL CLOCKWISE LOOP EAST OF FLORIDA BY DAY 5. ONLY THE GFDL...SHALLOW AND MEDIUM BAM...AND ECMWF MODELS TAKE OPHELIA WESTWARD ACROSS THE CENTRAL FLORIDA PENINSULA AND INTO THE EASTERN GULF. HOWEVER...THEY DO SO ALMOST IMMEDIATELY AND ALSO AS A VERY WEAK SYSTEM. GIVEN THAT OPHELIA IS ALREADY WELL EAST OF THOSE MODEL FORECASTS...AND THAT 500 MB HEIGHTS HAVE BEEN RISING MORE QUICKLY ALONG THE GULF COAST RATHER THAN FARTHER NORTH...SUGGESTS THAT THE GFDL AND ECMWF MOELS ARE BUILDING TOO MUCH RIDGING TOO THE NORTH OF OPHELIA. A WEAK SHORTWAVE TROUGH OVER THE CENTRAL U.S. IS EXPECTED TO GRADUALLY SLIDE SOUTHEASTWARD AND ERODE THE EASTERN PORTION OF THE RIDGE...WHICH SHOULD ALLOW FOR LIGHT NORTHWESTERLY MID-LEVEL FLOW TO DEVELOP OVER THE SOUTHEAST U.S. AND PUSH OPHELIA EASTWARD AWAY FROM FLORIDA BY 36-48 HOURS. THE FORECAST TRACK IS SIMILAR TO BUT SLOWER THAN THE NHC MODEL CONSENSUS AND IS TO THE RIGHT OF THE PREVIOUS FORECAST TRACK. HOWEVER...GIVEN THE UNCERTAINTY IN THE LONGER TIME PERIODS...POSSIBLE LANDFALL ACROSS NORTHERN FLORIDA OR GEORGIA DURING THE NEXT 5 DAYS CAN NOT BE RULED OUT AT THIS TIME. OPHELIAS IS EXPECTED TO REMAIN UNDER LIGHT TO MODERATE SOUTHERLY SHEAR FOR THE NEXT 2-3 DAYS...SO ONLY SLOW STRENGTHENING IS FORECAST. AFTER 72 HOURS...THE CYCLONE IS EXPECTED TO MOVE UNDERNEATH A NARROW 200 MB RIDGE AXIZ WHILE REMAINING OVER 29C SSTS...WHICH SHOULD ALLOW OPHELIA TO REACH HURRICANE STRENGTH. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 07/0900Z 28.3N 78.9W 35 KT 12HR VT 07/1800Z 28.5N 79.4W 40 KT 24HR VT 08/0600Z 28.8N 79.8W 45 KT 36HR VT 08/1800Z 29.0N 80.1W 50 KT 48HR VT 09/0600Z 29.4N 80.3W 55 KT 72HR VT 10/0600Z 29.8N 80.3W 60 KT 96HR VT 11/0600Z 30.1N 80.0W 65 KT 120HR VT 12/0600Z 30.0N 79.5W 70 KT |
