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| #378145 (Received by flhurricane at: 10:49 PM 22.Sep.2010) TCDAT4 TROPICAL STORM LISA DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL142010 1100 PM AST WED SEP 22 2010 LISA HAS CHANGED LITTLE IN ORGANIZATION DURING THE LAST SEVERAL HOURS. DEEP CONVECTION REMAINS CONFINED TO A SMALL AREA NEAR THE CENTER AND IN A BAND OVER THE NORTHEASTERN PORTION OF THE CIRCULATION. A 2340 UTC ASCAT PASS SHOWED MAXIMUM WINDS NEAR 30 KT OVER THE NORTHERN SEMICIRCLE. THE INITIAL WIND SPEED ESTIMATE IS LOWERED TO 35 KT...AND THIS MIGHT BE GENEROUS. LISA COULD STRENGTHEN DURING THE NEXT COUPLE OF DAYS AS IT REMAINS OVER MARGINALLY WARM WATER AND IN LOW WIND SHEAR ENVIRONMENT. AFTER THAT TIME...WESTERLY SHEAR IS ANTICIPATED TO INCREASE SIGNIFICANTLY AND THAT SHOULD PROMOTE STEADY WEAKENING. LISA HAS BEEN MOVING EASTWARD SINCE THE LAST ADVISORY...AND THE INITIAL MOTION ESTIMATE IS 090/4. THE TROPICAL CYCLONE WILL LIKELY CONTINUE TO MEANDER FOR THE NEXT 12 TO 24 HOURS AS IT REMAINS CAUGHT IN WEAK STEERING CURRENTS NEAR THE BASE OF A SHARP DEEP-LAYER TROUGH OVER THE EASTERN ATLANTIC. A TURN TO THE NORTHWEST WITH A GRADUAL INCREASE IN FORWARD SPEED IS FORECAST BEYOND 24 HOURS AS THE TROUGH CUTS-OFF AND SOME RIDGING DEVELOPS TO THE NORTHEAST OF THE CYCLONE. THE OFFICIAL TRACK FORECAST IS ADJUSTED A LITTLE TO THE RIGHT OF THE PREVIOUS ONE...DUE TO THE INITIAL POSITION AND MOTION AND TO BE IN BETTER AGREEMENT WITH THE LATEST GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 23/0300Z 17.7N 29.6W 35 KT 12HR VT 23/1200Z 17.8N 29.5W 35 KT 24HR VT 24/0000Z 18.0N 29.8W 40 KT 36HR VT 24/1200Z 18.4N 30.3W 45 KT 48HR VT 25/0000Z 19.1N 31.0W 45 KT 72HR VT 26/0000Z 21.0N 32.5W 45 KT 96HR VT 27/0000Z 23.0N 35.0W 40 KT 120HR VT 28/0000Z 25.5N 38.0W 30 KT $$ FORECASTER CANGIALOSI |
