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#10063 (Received by flhurricane at: 10:57 AM 25.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 25 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT SAT SEP 25 2004 EARLY MORNING VISIBLE SATELLITE IMAGERY INDICATES THAT THE LOW LEVEL CENTER REMAINS EXPOSED TO THE WEST OF THE DEEP CONVECTION. HOWEVER...IN THE LAST COUPLE HOURS A CONVECTIVE BAND HAS TRIED TO WRAP AROUND THE EAST SIDE OF THE CIRCULATION. CURRENT DVORAK INTENSITY ESTIMATES ARE 35 KT FROM ALL AGENCIES. LISA WILL REMAIN A 35 KT TROPICAL STORM. WIND RADII WERE EXPANDED A LITTLE BASED UPON A RECENT QUIKSCAT OVERPASS. INITIAL MOTION IS 320/8 KT. THE FORECAST REASONING REMAINS THE SAME FOR THE NEXT 72 HOURS. A LARGE MID/UPPER LEVEL TROUGH OVER THE CENTRAL ATLANTIC HAS WEAKENED THE SUBTROPICAL RIDGE WHICH WILL ALLOW LISA TO MOVE IN A NORTHWEST DIRECTION. LATER IN THE FORECAST PERIOD THE GLOBAL MODELS ARE INDICATING A TURN BACK TO THE WEST-NORTHWEST. THE MODELS INDICATE THAT THE TROUGH WILL LIFT OUT WITH A MID-LEVEL RIDGE IS EXPECTED TO BUILD ACROSS THE CENTRAL ATLANTIC. THIS IS THE SAME RIDGE THAT IS CURRENTLY STEERING HURRICANE JEANNE. THE UKMET...MOVES LISA SLOWER DURING THE EARLY PART OF THE FORECAST PERIOD AND THEREFORE TURNS THE CYCLONE MUCH SOONER AND IS FURTHER SOUTH. THE OFFICIAL FORECAST WAS ADJUSTED TO THE LEFT OF THE PREVIOUS TRACK AND IS BETWEEN THE GLOBAL MODEL CONSENSUS AND THE GFS SOLUTION. SHIPS MODEL WAS INITIALIZED WITH NORTHERLY SHEAR OF 17 KT OVER LISA. WATER VAPOR IMAGERY SUGGESTS THAT THE SHEAR MAY BE BEGINNING TO LESSON. THEREFORE...THE OFFICIAL FORECAST CALLS FOR SLOW STRENGTHENING THROUGH 72 HOURS. SHIPS MODEL INDICATES THAT THE SHEAR MAY REMAIN LOW BEYOND 72 HOURS ALLOWING LISA TO BECOME A HURRICANE. HOWEVER...THE OFFICIAL FORECAST WILL REMAIN CONSERVATIVE AND LEVEL OFF LISA JUST BELOW HURRICANE STRENGTH. FORECASTER BROWN/AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 25/1500Z 15.9N 45.6W 35 KT 12HR VT 26/0000Z 16.8N 46.4W 40 KT 24HR VT 26/1200Z 18.0N 47.2W 45 KT 36HR VT 27/0000Z 19.4N 47.9W 50 KT 48HR VT 27/1200Z 21.0N 48.5W 55 KT 72HR VT 28/1200Z 23.7N 50.0W 60 KT 96HR VT 29/1200Z 25.5N 51.5W 60 KT 120HR VT 30/1200Z 27.0N 54.0W 60 KT |