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| #46239 (Received by flhurricane at: 10:52 PM 15.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 40 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT THU SEP 15 2005 THE RADAR AND SATELLITE PRESENTATIONS OF OPHELIA CONTINUE TO DETERIORATE...WITH MINIMAL CONVECTION OVER THE WESTERN SEMICIRCLE OF THE SYSTEM. HIGHEST 850 MB FLIGHT-LEVEL WINDS FROM THE AIR FORCE HURRICANE HUNTERS WAS 74 KT SEVERAL HOURS AGO. CURRENT INTENSITY IS SET AT 60 KT. SINCE THE CYCLONE WILL NOT BE MOVING OVER SIGNIFICANTLY COOLER WATERS UNTIL ABOUT 36 HOURS...ONLY SLOW WEAKENING IS FORECAST DURING THE NEXT DAY OR SO. AFTER OPHELIA PASSES 40N LATITUDE...SEA SURFACE TEMPERATURES DECREASE RAPIDLY...AND OPHELIA SHOULD START ITS TRANSITION INTO A VIGOROUS EXTRATROPICAL CYCLONE AS IT BEGINS TO INTERACT WITH A BAROCLINIC ZONE NEAR NEW ENGLAND. THIS IS MORE OR LESS CONSISTENT WITH THE DIAGNOSIS OF THE GFS OUTPUT ON THE FSU CYCLONE PHASE ANALYSIS WEB PAGE...WHICH SHOWS THE SYSTEM BECOMING EXTRATROPICAL BY 72 HOURS. IT IS NOT POSSIBLE TO BE VERY PRECISE AS TO HOW TROPICAL THE CYCLONE WILL BE WHEN IT PASSES CLOSEST TO SOUTHEASTERN NEW ENGLAND. THE MOTION HAS BEEN ERRATIC OVER THE PAST 6 HOURS OR SO...BUT MOSTLY EASTWARD...OR EVEN EAST-SOUTHEASTWARD. CURRENT MOTION ESTIMATE IS AN UNCERTAIN 100/4. A 500 MB SHORTWAVE TROUGH CURRENTLY MOVING INTO ILLINOIS IS EXPECTED TO CONTINUE MOVING EASTWARD AND CAUSE OPHELIA TO TURN TOWARD THE NORTHEAST OR NORTH-NORTHEAST WITH A GRADUAL INCREASE IN FORWARD SPEED WITHIN A DAY OR TWO. THERE ARE DIFFERENCES AMONG THE VARIOUS TRACK MODELS AS TO HOW CLOSE OPHELIA WILL COME TO SOUTHEASTERN MASSACHUSETTS. THE NOGAPS TAKES THE CENTER NEAR CAPE COD...THE GFDL JUST A BIT FARTHER EAST...AND THE GFS CONTROL AND GFS ENSEMBLE MEAN ARE FARTHER OFFSHORE. OUT OF RESPECT FOR THE GFDL...THE NHC TRACK IS ADJUSTED ONLY SLIGHTLY TO THE LEFT. BASED ON THE LATEST FORECAST...THE TROPICAL STORM WATCH FOR SOUTHEASTERN NEW ENGLAND HAS BEEN EXTENDED A LITTLE FARTHER WESTWARD IN THIS ADVISORY PACKAGE. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 16/0300Z 34.5N 74.8W 60 KT 12HR VT 16/1200Z 35.5N 74.5W 60 KT 24HR VT 17/0000Z 37.2N 73.0W 55 KT 36HR VT 17/1200Z 40.0N 70.4W 55 KT...BECOMING EXTRATROPICAL 48HR VT 18/0000Z 43.0N 67.0W 50 KT...EXTRATROPICAL 72HR VT 19/0000Z 48.0N 55.0W 50 KT...INLAND...EXTRATROPICAL 96HR VT 20/0000Z 51.0N 41.0W 45 KT...EXTRATROPICAL 120HR VT 21/0000Z 54.0N 24.0W 45 KT...EXTRATROPICAL |
