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| #46272 (Received by flhurricane at: 4:37 AM 16.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 41 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI SEP 16 2005 SATELLITE...RADAR...AND RECONAISSANCE DATA INDICATE THAT OPHELIA CONTINUES TO LOSE ORGANIZATION...WITH THE MID-LEVEL CIRCULATION VISIBLE ON RADAR LOCATED TO THE EAST OF THE LOW-LEVEL CENTER DETERMINED BY AIRCRAFT AND DROPSONDES. FIRST SATELLITE IMAGES AFTER THE ECLIPSE SHOW THAT THE DEEP CONVECTION IS RESTRICTED TO THE EASTERN QUADRANT. THE INITIAL INTENSITY OF 55 KT IS BASED ON 850 MB FLIGHT LEVEL WINDS OF 71 KT...AND DROPSONDES REPORTING SURFACE WINDS IN THE 50-55 KT RANGE. OPHELIA IS SOUTH OF A WEAK 500 MB RIDGE IN THE WESTERLIES...WHICH ALONG WITH MID-LEVEL HIGH PRESSURE OVER BERMUDA...HAS BEEN IMPEDING THE MOTION OF THE CYCLONE AWAY FROM THE NORTH CAROLINA COAST. THE NEXT UPSTREAM TROUGH IS CURRENTLY OVER ILLINOIS. AS THIS TROUGH PROGRESSES EASTWARD OVER THE NEXT 24 HOURS...OPHELIA IS EXPECTED TO TURN NORTHEASTWARD AND ACCELERATE. MOST OF THE GLOBAL MODELS KEEP THE BERMUDA HIGH IN PLACE LONG ENOUGH TO FORCE OPHELIA ON A PATH CLOSE TO SOUTHERN NEW ENGLAND AND THE CANDIAN MARITIMES. MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON THE TRACK BUT WITH SOME DIFFERENCES IN SPEED. THE OFFICIAL FORECAST IS VERY CLOSE TO THE PREVIOUS ADVISORY AND THE DYNAMICAL MODEL CONSENSUS. HOWEVER...THE TILT OF THE VORTEX INDICATES THAT SHEAR IS BEGINNING TO AFFECT THE STORM STRUCTURE...AND SHOULD OPHELIA SHEAR OFF IT WOULD PROBABLY NOT ACCELERATE AS RAPIDLY AS FORECAST. ASSUMING THE TRACK IS ROUGHLY CORRECT...OPHELIA WILL BE OVER 20C WATER IN 36 HOURS AND WOULD LIKELY BE EXTRATROPICAL SHORTLY THEREAFTER. THE PRESSURE HAS RISEN MARKEDLY THIS EVENING BUT THERE HAS BEEN ONLY A MODEST DECREASE IN THE WINDS. ALL THE OBJECTIVE INTENSITY GUIDANCE SHOWS ONLY A SLIGHT ADDITIONAL DECREASE IN INTENSITY. AGAIN...SHOULD OPHELIA BECOME SHEARED IT WOULD LIKELY WEAKEN MORE RAPIDLY. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 16/0900Z 35.1N 74.8W 55 KT 12HR VT 16/1800Z 36.1N 74.0W 55 KT 24HR VT 17/0600Z 38.0N 72.0W 55 KT 36HR VT 17/1800Z 41.0N 69.0W 55 KT 48HR VT 18/0600Z 44.0N 64.0W 50 KT...EXTRATROPICAL 72HR VT 19/0600Z 48.5N 51.0W 50 KT...EXTRATROPICAL 96HR VT 20/0600Z 52.0N 36.0W 45 KT...EXTRATROPICAL 120HR VT 21/0600Z 54.0N 21.0W 45 KT...EXTRATROPICAL |
