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| #10909 (Received by flhurricane at: 10:39 PM 29.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 43 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT WED SEP 29 2004 A RAGGED EYE-LIKE FEATURE HAS APPEARED IN INFRARED IMAGERY. HOWEVER ...CONVECTION SURROUNDING THIS FEATURE IS SHALLOW WITH THE STRONGEST CONVECTION CONFINED TO THE SOUTHERN QUADRANT. A 29/1657Z CIMSS AMSU PRESSURE ESTIMATE WAS 981.7 MB AND A 29/2048Z QUIKSCAT OVERPASS REVEALED ONE 60-KT NON-RAINFLAGGED WIND VECTOR...SURROUNDED BY SEVERAL 50-55 KT UNFLAGGED VECTORS...IN THE DRY SLOT REGION IN THE SOUTHEAST QUADRANT. BASED ON THIS INFORMATION AND THE RAGGED EYE FEATURE...THE INITIAL INTENSITY IS BEING MAINTAINED AT 60 KT... DESPITE THE MUCH LOWER DVORAK SATELLITE INTENSITY ESTIMATES. THE INITIAL MOTION IS 340/09. LISA REMAINS ON TRACK AND IS NOW MOVING NORTH-NORTHWESTWARD AROUND THE NORTHEAST PERIPHERY OF AN UPPER-LEVEL LOW. AS THE LOW DROPS TO THE SOUTH...LISA IS EXPECTED TO BRIEFLY TURN NORTHWESTWARD BEFORE TURNING SLOWLY NORTHWARD THROUGH A BREAK IN THE SUBTROPICAL RIDGE AXIS. BY 48 HOURS...THE CYCLONE IS FORECAST TO GET PICKED UP BY AN APPROACHING SHORTWAVE TROUGH...AND BECOME EXTRATROPICAL OR MERGE WITH AN EXTRATROPICAL LOW BY 72 HOURS. THE OFFICIAL FORECAST IS A LITTLE TO THE RIGHT OF THE MODEL CONSENSUS DUE TO THE THE GFDL APPEARING TO BE AN EXTREME WESTERN OUTLIER MODEL THAT IS PRODUCING A CONSENSUS WEST BIAS. THE WINDOW OF OPPORTUNITY FOR ADDITIONAL STRENGTHENING IS GRADUALLY CLOSING. LISA HAS A SHALLOW EYE FEATURE AND WILL BE OVER 26C SSTS FOR ANOTHER 12 HOURS OR SO...WHILE REMAINING UNDER VERY LOW VERTICAL SHEAR CONDITIONS. THEREFORE...IT IS POSSIBLE THAT LISA COULD DEVELOP ENOUGH CONVECTION AROUND THE RAGGED EYE FEATURE LATER TONIGHT DURING THE USUAL NOCTURNAL CONVECTIVE MAXIMUM PERIOD... ALLOWING THE CYCLONE TO BRIEFLY BECOME A HURRICANE. BY 24 HOURS... LISA WILL BE MOVING OVER 25C AND LOWER SSTS...WHICH SHOULD BRING ABOUT SLOW WEAKENING EVEN THOUGH THE SHEAR IS FORECAST TO BE LESS THAN 10 KT. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 30/0300Z 31.5N 46.2W 60 KT 12HR VT 30/1200Z 32.8N 47.0W 65 KT 24HR VT 01/0000Z 34.7N 47.5W 60 KT 36HR VT 01/1200Z 36.7N 47.0W 60 KT 48HR VT 02/0000Z 38.6N 45.0W 55 KT...BECOMING EXTRATROPICAL 72HR VT 03/0000Z 42.5N 37.5W 45 KT...EXTRATROPICAL 96HR VT 04/0000Z...ABSORBED BY LARGER EXTRATROPICAL LOW |
