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| #10712 (Received by flhurricane at: 10:37 PM 27.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 35 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT MON SEP 27 2004 LISA REMAINS IN A SHEARED STATE...BUT THE CYCLONE HAS MANAGED TO KEEP GENERATING NEW CONVECTION NEAR AND TO THE NORTHEAST OF THE TIGHT LOW-LEVEL CIRCULATION CENTER. THE INITIAL INTENSITY ESTIMATE OF 35 KT IS BASED ON NUMEROUS 30-34 KT NON-RAINFLAGGED WIND VECTORS NOTED IN A 27/2142Z QUIKSCAT OVERPASS. WIND SPEEDS OBVIOUSLY COULD BE HIGHER IN THE DEEPER CONVECTION IN THE NORTHEAST QUADRANT...BUT I HAVE OPTED TO KEEP THE INTENSITY A LITTLE LOWER DUE TO THE RAPID FLUCTUATIONS IN THE CONVECTION IN THAT REGION. THIS LOWER INTENSITY IS ALSO CONSISTENT WITH THE 1006 MB PRESSURE AND 34 KT WIND ESTIMATES OBTAINED FROM A 27/2046Z AMSU OVERPASS. THE INITIAL MOTION ESTIMATE IS 350/07. THE INITIAL POSITION WAS ADJUSTED SLIGHTLY EASTWARD BASED ON AMSU OVERPASS AND QUIKSCAT POSITION ESTIMATES. OTHER THAN THAT...THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK REASONING. LISA IS EXPECTED TO MOVE SLOWLY NORTHWARD BETWEEN A RIDGE TO THE EAST AND A WEAK TROUGH TO THE WEST. BY 72 HOURS...A SHORTWAVE TROUGH IS FORECAST TO APPROACH LISA FROM THE WEST AND GRADUALLY RECURVE THE CYCLONE NORTHEASTWARD. ALL OF THE NHC MODEL GUIDANCE AGREES ON THIS SCENARIO...AND THE TIMING OF THE NORTHEASTWARD TURN IS THE ONLY DIFFERENCE BETWEEN THE MODELS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE NHC MODEL CONSENSUS. LISA IS FORECAST TO REMAIN UNDER SOUTH TO SOUTHWESTERLY VERTICAL SHEAR FOR THE NEXT 36 HOURS SO LITTLE...IF ANY...SIGNIFICANT INTENSIFICATION IS EXPECTED DURING THAT TIME. HOWEVER...BY 48-96 HOURS...THE SHEAR IS EXPECTED TO WEAKEN TO LESS THAN 10 KT WHILE LISA IS STILL OVER 27+ CELSIUS SSTS. THIS SHOULD ALLOW FOR SOME STRENGTHENING TO OCCUR AND LISA COULD POSSIBLY EVEN REACH MINIMAL HURRICANE STRENGTH BEFORE INCREASING WESTERLY SHEAR AND COOLER SSTS INITIATE A WEAKENING TREND BY 120 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 28/0300Z 22.3N 46.4W 35 KT 12HR VT 28/1200Z 23.4N 46.6W 35 KT 24HR VT 29/0000Z 24.9N 46.9W 35 KT 36HR VT 29/1200Z 27.0N 47.2W 40 KT 48HR VT 30/0000Z 29.0N 47.3W 45 KT 72HR VT 01/0000Z 32.0N 47.8W 55 KT 96HR VT 02/0000Z 35.5N 47.0W 60 KT 120HR VT 03/0000Z 37.5N 44.5W 55 KT |
