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| #111788 (Received by flhurricane at: 10:55 AM 19.Sep.2006) TCDAT3 HURRICANE HELENE DISCUSSION NUMBER 29 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082006 ISSUED BY THE HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 1100 AM EDT TUE SEP 19 2006 HURRICANE HELENE REMAINS AN IMPRESSIVE TROPICAL CYCLONE THIS MORNING. THE SYSTEM IS SLIGHTLY ELONGATED BUT MAINTAINS ITS CENTRAL CORE OF DEEP CONVECTION... EYE FEATURE AND ALMOST PERFECT OUTFLOW. DVORAK INTENSITY T-NUMBERS PERSIST AT 5.5 FROM ALL AGENCIES... THE INITIAL INTENSITY WILL REMAIN AT 100 KTS AND THE INITIAL MOTION WILL BE 285/7. AT THIS MOMENT AND FOR THE NEXT 24 HOURS OR SO... HELENE WILL REMAIN UNDER A DOMINANT UPPER-LEVEL RIDGE BASED OVER THE CENTRAL ATLANTIC. THIS RIDGE WILL SHOULD STEER HELENE OFF TO THE WEST NORTHWEST FOR THE NEXT 24 TO 36 HOURS AND PERHAPS ALLOW FOR SOME FURTHER STRENGTHENING. A LARGE UPPER LOW... JUST OFF THE EAST COAST... AND VERY AMPLFIED UPPER-LEVEL TROUGH... OVER THE EASTERN STATES... WILL THEN PHASE AND BEGIN TO INFLUENCE HELENE. THE UPPER RIDGE OVER THE ATLANTIC WILL BREAK DOWN... HELENE WILL GET CAUGHT UP IN THE STRONG WESTERLIES AND BEGIN TO RECURVE/PROGRESS RAPIDLY DOWNSTREAM INTO THE OPEN WATERS OF THE NORTH ATLANTIC. AFTER 36 HOURS... HELENE SHOULD BEGIN TO GRADUALLY WEAKEN. THE DYNAMICAL MODELS/OBJECTIVE AIDS AND GLOBAL MODELS ARE TIGHTLY CLUSTERED WITH THIS OVERALL TRACK AND RECURVATURE BEFORE 60W. THE ONLY SPREAD WITH THE GUIDANCE IS THE FORWARD SPEED AS HELENE TURNS NORTHWARD AND THE WESTERLIES BECOME INVOLVED. THE OPERATIONAL GFS IS THE MOST PROGRESSIVE WHILE THE UKMET AND ESPECIALLY THE HI-RES ECMWF ARE THE SLOWEST SOLUTIONS INTO THE MEDIUM RANGE PERIOD. HPC WILL FOLLOW THE CLOSE CONSENSUS OF THE DYNAMICAL MODELS... WHICH IS A COMPROMISE OF THESE TWO IDEAS. FORECAST POSITIONS AND MAX WINDS INITIAL 19/1500Z 24.6N 52.9W 100 KT 12HR VT 20/0000Z 25.0N 54.1W 105 KT 24HR VT 20/1200Z 25.9N 55.7W 110 KT 36HR VT 21/0000Z 27.5N 56.5W 110 KT 48HR VT 21/1200Z 29.7N 56.7W 105 KT 72HR VT 22/1200Z 35.0N 55.0W 100 KT 96HR VT 23/1200Z 39.5N 49.5W 90 KT 120HR VT 24/1200Z 45.0N 40.5W 80 KT $$ FORECASTER MUSHER |
