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| #378784 (Received by flhurricane at: 10:38 PM 25.Sep.2010) TCDAT4 TROPICAL STORM LISA DISCUSSION NUMBER 22 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL142010 1100 PM AST SAT SEP 25 2010 MICROWAVE IMAGES FROM THIS EVENING INDICATE THAT LISA HAS BEEN MOVING MORE TOWARD THE NORTH-NORTHWEST...WITH THE CENTER BECOMING EXPOSED TO THE SOUTHWEST OF VERY LIMITED DEEP CONVECTION. DVORAK CLASSIFICATIONS ARE DECREASING AS FAST AS THE RULES ALLOW...AND THE INITIAL WIND SPEED IS LOWERED TO 40 KT. COOL WATERS...DRY AIR...AND STRONG SOUTHWESTERLY SHEAR SHOULD FINISH OFF LISA BY MONDAY UNLESS THE CYCLONE PULLS ANOTHER SURPRISE. THE GUIDANCE IS IN GOOD AGREEMENT ON THE WEAKENING SCENARIO...AND THE OFFICIAL FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE. BASED ON SSMI/S IMAGES FROM EARLIER THE LOW-LEVEL CENTER HAS BEEN RELOCATED FARTHER WEST...AND IS MOVING AT ABOUT 340/8. A NORTH- NORTHWESTWARD MOTION IS EXPECTED UNTIL DISSIPATION IN A DAY OR TWO AS THE CYCLONE MOVES BETWEEN A TROUGH OVER THE EASTERN ATLANTIC OCEAN AND RIDGE NEAR NORTHWESTERN AFRICA. SOME MODEL GUIDANCE... SUCH AS THE HWRF/GFDL...SHOW THE CYCLONE TAKING A TRACK TOWARD THE NORTH OR NORTH-NORTHEAST...BUT THESE MODELS ALSO HAVE A MUCH MORE VERTICALLY COHERENT CYCLONE. SINCE THIS STRUCTURE IS UNLIKELY TO OCCUR...THE NHC FORECAST WILL REMAIN ON THE LEFT SIDE OF THE GUIDANCE. THE NEW FORECAST HAS BEEN SHIFTED TO THE WEST...BUT THAT IS MOSTLY DUE TO THE CENTER RELOCATION. THE REMNANT LOW SHOULD MOVE VERY SLOWLY BY THE END OF THE PERIOD AS SURFACE HIGH PRESSURE BUILDS NEAR THE AZORES. FORECAST POSITIONS AND MAX WINDS INITIAL 26/0300Z 24.3N 29.0W 40 KT 12HR VT 26/1200Z 25.3N 29.3W 35 KT 24HR VT 27/0000Z 26.5N 29.6W 30 KT 36HR VT 27/1200Z 27.8N 30.0W 25 KT...POST-TROP/REMNT LOW 48HR VT 28/0000Z 29.2N 30.6W 25 KT...POST-TROP/REMNT LOW 72HR VT 29/0000Z 31.0N 31.0W 25 KT...POST-TROP/REMNT LOW 96HR VT 30/0000Z 32.0N 31.0W 20 KT...POST-TROP/REMNT LOW 120HR VT 01/0000Z...DISSIPATED $$ FORECASTER BLAKE |
