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| #9852 (Received by flhurricane at: 5:14 AM 24.Sep.2004) TCDAT3 TROPICAL DEPRESSION LISA DISCUSSION NUMBER 20 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI SEP 24 2004 SHORTWAVE AND ENHANCED BD INFRARED IMAGERY SUGGEST THAT THE PREVIOUSLY EXPOSED LOW-LEVEL CIRCULATION CENTER HAS BEGUN TO MOVE BENEATH THE NORTHEASTERN EDGE OF THE DEVELOPING DEEP CONVECTION. THIS LEADS US TO BELIEVE THAT THE NORTHERLY SHEAR MAY BE DECREASING SOMEWHAT. DVORAK CURRENT SATELLITE INTENSITY ESTIMATES ARE 35 KT FROM TAFB AND 30 KT FROM SAB. THE INITIAL INTENSITY WILL REMAIN AT 30 KT BASED PRIMARILY ON A 24/0511Z TRMM OVERPASS WHICH INDICATED A POORLY DEFINED LOW CENTER. SHIPS SUGGESTS WEAKENING OF THE NORTHERLY SHEAR DURING THE NEXT 48 HOURS. AFTER THE 48 HOUR PERIOD...THE INTENSITY MODEL INDICATES THAT LISA WILL ENCOUNTER INCREASING SOUTHWESTERLY SHEAR AHEAD OF AN APPROACHING MID/UPPER TROUGH FROM THE NORTHWEST...BUT NOT SIGNFICANT ENOUGH TO PREVENT FURTHER INTENSIFICATION. THE GFS ON THE OTHER HAND INDICATES STRONGER SOUTHWESTERLY SHEAR AT THE SAME TIMEFRAME AND OPENS THE TROPICAL CYCLONE INTO A WAVE. THE OFFICIAL FORECAST CALLS FOR GRADUAL STRENGTHENING THROUGH THE ENTIRE FORECAST AND IS BASED PRIMARILY ON THE SHIPS MODEL. INITIAL MOTION IS 280/9 KT. THERE IS NO CHANGE TO THE TRACK FORECAST REASONING FROM THE PREVIOUS PACKAGE. A WEAKENING RIDGE TO THE NORTH SHOULD INFLUENCE A WEST-NORTHWEST MOTION DURING THE NEXT 24 HOURS. THEREAFTER AN APPROACHING MID LEVEL TROUGH SHOULD INDUCE A TURN TOWARD THE NORTHWEST AND NORTH-NORTHWEST. THE OFFICIAL FORECAST IS SLIGHTLY TO THE LEFT OF THE PREVIOUS FORECAST AND IS BASED ON THE CONU CONSENSUS. FORECASTER ROBERTS/BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 14.6N 43.5W 30 KT 12HR VT 24/1800Z 15.2N 44.6W 35 KT 24HR VT 25/0600Z 16.5N 45.7W 40 KT 36HR VT 25/1800Z 18.0N 46.5W 45 KT 48HR VT 26/0600Z 19.5N 47.2W 55 KT 72HR VT 27/0600Z 23.5N 47.5W 55 KT 96HR VT 28/0600Z 28.0N 46.0W 60 KT 120HR VT 29/0600Z 33.0N 43.5W 60 KT |
