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#10672 (Received by flhurricane at: 4:37 PM 27.Sep.2004) TCDAT3 TROPICAL STORM LISA DISCUSSION NUMBER 34 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT MON SEP 27 2004 LATEST SATELLITE IMAGERY CONTINUES TO DEPICT A SHEARED SYSTEM...WITH THE LOW-LEVEL CENTER EXPOSED TO THE SOUTHWEST OF THE MAIN AREA OF DEEP CONVECTION. THERE IS NO REASON TO EXPECT THIS SHEAR TO RELAX SOON...SO THE INTENSITY FORECAST SHOWS LITTLE CHANGE IN STRENGTH FOR THE NEXT 1-2 DAYS. LATER IN THE FORECAST PERIOD...AN UPPER-LEVEL LOW TO THE WEST OF LISA IS FORECAST TO BREAK UP AND THIS MAY ALLOW FOR A MORE FAVORABLE UPPER-LEVEL ENVIRONMENT. THE CURRENT NHC WIND SPEED FORECAST SHOWS A LITTLE LESS STRENGTHENING THAN THE PREVIOUS ONES AND IS IN REASONABLE AGREEMENT WITH THE LATEST SHIPS GUIDANCE. THE CURRENT GFDL RUN SHOWS MORE STRENGTHENING...BUT THAT MODEL HAS BEEN EXHIBITING A POSITIVE BIAS FOR THIS STORM THUS FAR. LATEST FIXES SHOW A SLIGHTLY FASTER MOTION TO THE NNW...340/7. LISA IS BEING STEERED BY THE FLOW ON THE SOUTHWESTERN SIDE OF A MID-LEVEL SUBTROPICAL ANTICYCLONE. TRACK GUIDANCE NOW SUGGESTS MORE OF A NORTHEASTWARD TURN LATER IN THE PERIOD DUE TO A WEAK APPROACHING SHORTWAVE IN THE WESTERLIES. WE HAVE NOT ENTIRELY BOUGHT INTO THIS CHANGE...BUT HAVE SHIFTED THE TRACK SOMEWHAT TO THE EAST...TO BE AT LEAST PARTIALLY CONSISTENT WITH THE NEW GUIDANCE. IT SHOULD BE NOTED THAT THE DYNAMICAL MODEL CONSENSUS IS EVEN FARTHER TO THE NORTHEAST OF THE OFFICIAL FORECAST. FORECASTER PASCH/SISKO FORECAST POSITIONS AND MAX WINDS INITIAL 27/2100Z 21.5N 46.5W 35 KT 12HR VT 28/0600Z 22.5N 47.1W 35 KT 24HR VT 28/1800Z 24.0N 47.9W 35 KT 36HR VT 29/0600Z 25.5N 48.3W 35 KT 48HR VT 29/1800Z 27.0N 48.5W 40 KT 72HR VT 30/1800Z 30.5N 49.0W 50 KT 96HR VT 01/1800Z 33.0N 49.0W 60 KT 120HR VT 02/1800Z 35.0N 48.0W 60 KT |