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| #9508 (Received by flhurricane at: 4:44 AM 22.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT WED SEP 22 2004 THE SYSTEM CONTINUES AS A RATHER SMALL...AMORPHOUS...BLOB OF DEEP CONVECTION ON SATELLITE IMAGES. ALTHOUGH THE CLOUD TOPS ARE VERY COLD...THERE IS LITTLE ORGANIZATION OTHER THAN A CONCENTRATION NEAR THE CENTER. BASED ON DVORAK CLASSIFICATIONS... THE INTENSITY IS ADJUSTED DOWNWARD SLIGHTLY. THERE IS SOME CONCERN ABOUT HOW THE EVOLUTION OF THE STORM WILL BE AFFECTED BY THE DISTURBANCE TO ITS EAST-SOUTHEAST. THE LATTER SYSTEM COULD ALSO BECOME A TROPICAL CYCLONE...AND WOULD PROBABLY BE A LARGER ONE THAN LISA. THUS IT IS POSSIBLE THAT THE LARGER SYSTEM COULD ABSORB LISA. OTHERWISE THE ENVIRONMENT IS MARGINALLY FAVORABLE FOR STRENGTHENING. THE OFFICIAL FORECAST SHOWS SOME STRENGTHENING BUT IS BELOW THE SHIPS GUIDANCE BEYOND 2 DAYS BECAUSE OF THE POTENTIALLY UNFAVORABLE INFLUENCE OF THE SYSTEM TO THE EAST. IT IS NOT EASY TO LOCATE THE CENTER...BUT...BECAUSE OF THE MODERATE EAST-NORTHEASTERLY SHEARING ENVIRONMENT...IT IS ESTIMATED TO BE NEAR THE EASTERN EDGE OF THE DENSE OVERCAST. THE INITIAL MOTION IS ESTIMATED TO BE 285/6. TRACK GUIDANCE IS FAR FROM STRAIGHTFORWARD...WITH CONSIDERABLE SCATTER AMONG THOSE DYNAMICAL MODELS THAT ARE ABLE TO TRACK A CENTER IN THEIR FORECAST FIELDS. THE GFDL MODEL SHOWS A SHARP SOUTHWARD TURN FOLLOWED BY A SHARP NORTHWARD TURN. THE NOGAPS SHOWS ERRATIC MOTION...AND THE GFS LOSES THE VORTEX IN ITS OUTPUT. ONLY THE U.K. MET OFFICE MODEL TRACK IS SOMEWHAT CLIMATOLOGICAL...SINCE IT DEPICTS A GRADUAL TURN TO THE NORTHWEST. THAT DOES NOT SEEM TO BE AN UNREASONABLE SCENARIO...SINCE I DO NOT EXPECT LISA TO HAVE MUCH OF A MID-LEVEL RIDGE TO ITS NORTH OVER THE NEXT SEVERAL DAYS. GIVEN THE UNCERTAINTIES AND DIVERGENCE IN THE MODEL OUTPUT...THE OFFICIAL FORECAST IS EVEN SLOWER THAN THE PREVIOUS ONE. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 22/0900Z 14.5N 41.2W 55 KT 12HR VT 22/1800Z 14.8N 42.0W 55 KT 24HR VT 23/0600Z 15.2N 43.2W 55 KT 36HR VT 23/1800Z 15.6N 44.3W 60 KT 48HR VT 24/0600Z 15.8N 45.0W 65 KT 72HR VT 25/0600Z 16.5N 46.5W 70 KT 96HR VT 26/0600Z 17.5N 48.0W 70 KT 120HR VT 27/0600Z 18.5N 49.0W 70 KT |
