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| #10395 (Received by flhurricane at: 4:47 PM 26.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 30 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT SUN SEP 26 2004 THE CENTER OF LISA IS PARTIALLY EXPOSED AS THE CONVECTION REMAINS PRIMARILY IN THE NORTHEAST QUADRANT AND WESTERLY SHEAR IMPACTS THE SYSTEM. VISIBLE IMAGERY SUGGESTS THAT THE CENTER IS ELONGATED IN THE NORTH-SOUTH DIRECTION. THE INITIAL INTENSITY HAS BEEN DECREASED TO 45 KTS BASED ON TAFB AND SAB ESTIMATES THAT INDICATE A SLIGHT DOWNWARD INTENSITY TREND. IN ADDITION...THE CLOUD TOP TEMPERATURES IN THE PRIMARY CONVECTION HAVE ALSO DESCREASED SO THE INITIAL IS SET TO 45 KTS. INITIAL MOTION IS ESTIMATED TO BE 355/7. THE SHORT TERM MOTION HAS BEEN NEARLY DUE NORTH...HOWEVER THE MODEL GUIDANCE DEPICTS THE MOVEMENT OF LISA WILL BE PRIMARILY TO THE NORTH-NORTHWEST. LISA IS CURRENTLY POSITIONED ON THE SOUTHEAST SIDE OF A MID-LEVEL HIGH PRESSURE SYSTEM. LATER IN THE FORECAST PERIOD...LISA IS STEERED ABOUT BY AN UPPER LOW LOCATED WEST OF THE SYSTEM. FOR THIS ADVISORY...THE FORECAST GUIDANCE IS IN GOOD AGREEMENT ALTHOUGH THE GFS IS GENERALLY LEFT OF TRACK EARLY IN THE FORECAST PERIOD AND REJOINS THE GUIDANCE GROUP AT 72 HRS...AFTER WHICH THE VORTEX TRACKERS LOSE THE CIRCULATION. THE FORECAST TRACK IS JUST TWEAKED A BIT TOWARD CONU AND THE GUNS CONSENSUS WITH THE GREATEST ADJUSTMENT OCCURRING AT 120 HRS. THE INTENSITY FORECAST MODELS DO NOT STRENGTHEN LISA ABOVE TROPICAL STORM STRENGTH UNTIL AFTER 72 HRS. BY THIS TIME THE VERTICAL SHEAR DECREASES TO LOW VALUES...SO THE WINDOW FOR ANY SIGNIFICANT DEVELOPMENT IN LISA WOULD OCCUR LATER IN THE FORECAST PERIOD. THERE IS LITTLE CHANGE IN THE NHC INTENSITY FORECAST. NO SIGNIFICANT CHANGE IS EXPECTED FROM 0-72 HRS...BUT LISA MAY REACH HURRICANE STRENGTH IN THE EXTENDED TIME PERIOD...IF IT CAN SURVIVE THE CURRENT SHEAR. FORECASTER SISKO/PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 26/2100Z 19.7N 46.1W 45 KT 12HR VT 27/0600Z 20.9N 46.6W 45 KT 24HR VT 27/1800Z 22.5N 47.5W 45 KT 36HR VT 28/0600Z 23.8N 48.4W 50 KT 48HR VT 28/1800Z 25.2N 48.9W 55 KT 72HR VT 29/1800Z 28.1N 50.0W 65 KT 96HR VT 30/1800Z 30.5N 51.0W 65 KT 120HR VT 01/1800Z 32.5N 52.0W 65 KT |
