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| #10544 (Received by flhurricane at: 5:03 AM 27.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 32 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT MON SEP 27 2004 LISA HAS REMAINED STEADY-STATE OVERNIGHT WITH LITTLE CHANGE IN THE SHEARED CONVECTIVE PATTERN...WITH NO NET CHANGE IN THE DEPTH OF THE CONVECTION WHICH HAS BEEN PULSATING NORTHEAST OF THE CENTER. THE INITIAL INTENSITY OF 45 KT IS UNCHANGED FROM THE PREVIOUS ADVISORY AND IS BASED ON DVORAK CI NUMBERS OF 3.0 FROM TAFB...SAB...AND AFWA. SHORTWAVE IR IMAGERY FROM GOES-12 AND METEOSAT-8 INDICATE A CONTINUED SLOW MOTION...ESTIMATED TO BE JUST WEST OF DUE NORTH AT ABOUT 5 KT. LISA IS EMBEDDED WITHIN WEAK STEERING CURRENTS IN BETWEEN RIDGING TO THE EAST AND WEST. MOST OF THE DYNAMICAL MODELS...WITH THE EXCEPTION BEING THE UKMET...INSIST THAT A TURN TOWARD THE NORTH-NORTHWEST WILL BEGIN VERY SOON AS THE EASTERN RIDGE BUILDS SLIGHTLY TO THE NORTH AND NORTHEAST OF LISA. THE OFFICIAL FORECAST FOLLOWS A CONSENSUS OF THE DYNAMICAL MODELS THROUGH ABOUT 48 HOURS. THE MODELS DIVERGE SIGNIFICANTLY AT DAYS THREE THROUGH FIVE...WITH THE NOGAPS AND GFDL SHOWING A SLOW NORTHWESTWARD MOTION...AND THE GFS AND UKMET DEPICTING RECURVATURE FOLLOWED BY RAPID MOTION TO THE NORTHEAST. THE UKMET SEEMS A BIT FAST INITIALLY...AND THE GFS TRACK RESULTS FROM THE MODEL FORMING A NEW VORTEX WELL TO THE NORTHEAST OF THE CURRENT ONE...SO WE ARE NOT QUITE READY TO FOLLOW THESE SOLUTIONS. THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO THE EAST THROUGH 72 HOURS...AND THEREAFTER IS VERY SIMILAR TO THE PREVIOUS ADVISORY. THE UNCERTAINTY IN THIS FORECAST REMAINS LARGE. UNTIL THE CURRENT SOUTHWESTERLY SHEAR RELAXES IN 36 TO 48 HOURS...AS FORECAST BY THE GFS/SHIPS...THE INTENSITY SHOULD REMAIN FAIRLY STEADY. THEREAFTER...WITH WEAKER SHEAR AND SSTS STILL GREATER THAN 27 DEGREES CELSIUS...BOTH SHIPS AND GFDL FORECAST SHOW INTENSIFICATION TO HURRICANE STRENGTH BY 72 HOURS. THE OFFICIAL FORECAST FOLLOWS THIS SCENARIO. FORECASTER KNABB/FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 27/0900Z 20.2N 46.2W 45 KT 12HR VT 27/1800Z 21.4N 46.5W 45 KT 24HR VT 28/0600Z 22.8N 47.3W 45 KT 36HR VT 28/1800Z 24.2N 48.1W 50 KT 48HR VT 29/0600Z 25.6N 48.9W 55 KT 72HR VT 30/0600Z 28.0N 50.1W 65 KT 96HR VT 01/0600Z 30.0N 51.0W 65 KT 120HR VT 02/0600Z 31.5N 51.5W 65 KT |
