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| #45072 (Received by flhurricane at: 5:11 AM 10.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SAT SEP 10 2005 RECON REPORTS THROUGH 06Z LOCATED THE CENTER WITHIN A LONE BURST OF DEEP CONVECTION THAT HAS BEEN ROTATING SOMEWHAT WITHIN A LARGER MID-LEVEL CIRCULATION...WHICH IS STILL MOVING GENERALLY NORTHEASTWARD. THE MINIMUM CENTRAL PRESSURE MEASUREMENTS BY DROPSONDE WERE 983-985 MB... BUT MAXIMUM 850 MB FLIGHT LEVEL WINDS WERE 70 KT...CORRESPONDING TO ABOUT 56 KT AT THE SURFACE. DVORAK T-NUMBERS HAVE ALSO COME DOWN TO 3.5. THE ADVISORY INTENSITY IS SET TO 60 KT. WHILE THIS MAKES OPHELIA A TROPICAL STORM RATHER THAN A HURRICANE... THE WEAKENING IS ONLY SLIGHT AND RESTRENGTHENING IS FORECAST. THE INITIAL MOTION ESTIMATE IS 035/9... BUT THIS NORTHEASTWARD MOTION IS DECEPTIVE SINCE IT IS EXPECTED TO PERSIST FOR ONLY ABOUT 12 MORE HOURS... OR LESS. AS THE DEEP LAYER TROUGH CURRENTLY OVER THE EAST COAST OF THE U.S. PROCEEDS WELL OFFSHORE OVER THE NORTHERN ATLANTIC DURING THE NEXT FEW DAYS... A STRONG AND DEEP RIDGE IS FORECAST BY ALL OF THE DYNAMICAL MODELS TO BUILD IN ITS PLACE. THIS PATTERN SHOULD STOP OPHELIA FROM MOVING OUT TO SEA AND INSTEAD PERHAPS FORCE IT WESTWARD AND TOWARD THE SOUTHEAST U.S. COAST. HOW LONG IT WILL TAKE FOR THIS SCENARIO TO EVOLVE IS NOT AGREED UPON BY THE DYNAMICAL MODELS. THE GFS SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT MOTION...AND IT ALONG WITH THE GFDL BRING OPHELIA TO THE COAST THE FASTEST. CONVERSELY...THE NOGAPS AND UKMET STALL THE SYSTEM OFFSHORE LONGER BUT EVENTUALLY BRING IT TO THE COAST. ALTHOUGH THIS REMAINS A FAIRLY UNCERTAIN FORECAST...THE NEW OFFICIAL FORECAST FAVORS THE GFS AND GFDL SOLUTIONS...AND IS SIMILAR TO THE PREVIOUS ADVISORY WITH JUST A SLIGHT ADJUSTMENT NORTHWARD. OPHELIA IS STRUGGLING AGAINST WEST-SOUTHWESTERLY SHEAR AND SOME VERY DRY MIDDLE AND UPPER LEVEL AIR OVER THE SOUTHEASTERN STATES... ALTHOUGH THIS APPEARS TO BE IMPACTING THE CYCLONE MOSTLY BENEATH ITS UPPER LEVEL OUTFLOW LAYER SINCE CIRRUS IS STILL FANNING OUT TO THE SOUTHWEST FROM THE CENTER. THE RIDGE THAT BUILDS NORTH OF OPHELIA IN A COUPLE OF DAYS WILL PROBABLY CREATE AN ENVIRONMENT MORE CONDUCIVE FOR STRENGTHENING. THE SHIPS MODEL NOW ONLY PEAKS AT 68 KT...WHILE GFDL FORECASTS NEAR 85 KT...WITHIN THE NEXT 36 HOURS. THE OFFICIAL FORECAST WILL CONTINUE TO SHOW 85 KT PRIOR TO LANDFALL GIVEN THE LESS HOSTILE ENVIRONMENT EXPECTED TO UNFOLD SOUTH OF THE RIDGE. WATCHES COULD BE REQUIRED FOR PORTIONS OF THE SOUTHEASTERN U.S. COAST LATER TODAY. FORECASTER KNABB FORECAST POSITIONS AND MAX WINDS INITIAL 10/0900Z 31.2N 76.8W 60 KT 12HR VT 10/1800Z 31.7N 76.5W 65 KT 24HR VT 11/0600Z 31.9N 76.7W 70 KT 36HR VT 11/1800Z 32.0N 77.3W 75 KT 48HR VT 12/0600Z 32.3N 78.0W 80 KT 72HR VT 13/0600Z 33.0N 79.5W 80 KT 96HR VT 14/0600Z 34.5N 79.5W 45 KT...INLAND 120HR VT 15/0600Z 37.0N 77.5W 30 KT...INLAND |
