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| #9904 (Received by flhurricane at: 10:58 AM 24.Sep.2004) TCDAT3 TROPICAL DEPRESSION LISA DISCUSSION NUMBER 21 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 AM EDT FRI SEP 24 2004 EARLY MORNING VISIBLE SATELLITE IMAGERY SHOWED THAT THE CENTER OF THE TROPICAL CYCLONE WAS NEAR THE NORTH EDGE OF THE DEEP CONVECTION...AND AN 0852 UTC QUIKSCAT DATA SUGGESTED THAT LISA WAS LIKELY A TROPICAL STORM OVERNIGHT. 12Z DVORAK INTENSITY ESTIMATES WERE 35 KT FROM ALL AGENCIES. HOWEVER...SINCE THEN THE LOW LEVEL CENTER HAS ONCE AGAIN BECOME EXPOSED AND IS NOW LOCATED ABOUT 70 NM NORTH OF THE CONVECTION. THEREFORE LISA WILL REMAIN A 30 KT TROPICAL DEPRESSION FOR THIS ADVISORY. THE CENTER HAS BEEN RELOCATED SOUTHWARD BASED ON VISIBLE SATELLITE IMAGERY. THE INITIAL MOTION IS HARD TO DETERMINE...BUT 24 HOUR SATELLITE LOOPS SUGGEST THAT LISA COMPLETED ITS ORIGINAL CYCLONIC LOOP LATE YESTERDAY AND THEN MOVED WEST-SOUTHWESTWARD FOR A TIME OVERNIGHT. IT IS ASSUMED THAT A WEST-NORTHWEST MOTION WILL RESUME SHORTLY AND THE INITIAL MOTION IS ESTIMATED TO BE 285/7 KT. THE FORECAST TRACK REMAINS SIMILAR TO THE PREVIOUS ONE THROUGH 72 HOURS. THE RIDGE NORTH OF LISA WILL CONTINUE TO WEAKEN AS A LARGE MID/UPPER LEVEL TROUGH MOVES SOUTHEAST INTO THE CENTRAL ATLANTIC. THIS SHOULD TURN LISA NORTHWESTWARD AND NORTHWARD DURING THE NEXT 48 TO 72 HOURS. IN THE LONGER RANGE...THE GFS AND GFDL INDICATE THAT THE TROUGH MAY NOT COMPLETELY PICK UP THE CYCLONE WHILE THE NOGAPS AND UKMET ARE MUCH FASTER AND FURTHER NORTHEAST. THE OFFICIAL TRACK INDICATES A SOMEWHAT SLOWER MOTION AT 96 AND 120 HOURS THAN THE PREVIOUS ADVISORY AND LEANS A LITTLE CLOSER TO THE GFS/GFDL SOLUTION. GLOBAL MODELS SUGGESTS THAT THE NORTHERLY SHEAR SHOULD WEAKEN A LITTLE DURING THE NEXT 24-36 HOURS. THE OFFICIAL FORECAST CALLS FOR SLOW STRENGTHENING THROUGH 72 HOURS THEN LEVELS OFF THE INTENSITY AS LISA IS EXPECTED TO ENCOUNTER SOUTHWESTERLY SHEAR AHEAD OF THE MID/UPPER LEVEL TROUGH. THE INTENSITY FORECAST IS NOT NEARLY AS AGGRESSIVE AS THE SHIPS MODEL...WHICH BRINGS LISA TO A HURRICANE IN 60 HOURS. THE 12Z RUN OF THIS MODEL WAS ALSO INITIALIZED WHEN LISA APPEARED TO BE STRONGER THAN IT DOES NOW. FORECASTER BROWN/FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 24/1500Z 14.1N 43.3W 30 KT 12HR VT 25/0000Z 14.8N 44.3W 30 KT 24HR VT 25/1200Z 16.3N 45.5W 35 KT 36HR VT 26/0000Z 17.8N 46.2W 40 KT 48HR VT 26/1200Z 19.8N 46.7W 50 KT 72HR VT 27/1200Z 24.0N 46.4W 55 KT 96HR VT 28/1200Z 28.0N 45.0W 55 KT 120HR VT 29/1200Z 31.5N 43.5W 55 KT |
