ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GABRIELLE DISCUSSION NUMBER 8 NATIONAL WEATHER SERVICE MIAMI FL 11 AM EDT THU SEP 13 2001 TWO SURFACE OBSERVATIONS...FROM SHIPS WITH CALL SIGNS DCUW AND WCZ5238...OF 35 AND 40-KNOT WINDS RESPECTIVELY...AS WELL AS DVORAK CLASSIFICATIONS OF T2.5 FROM TAFB AND SAB...SUPPORT UPGRADING THE CYCLONE TO TROPICAL STORM GABRIELLE. THERE IS SOME SOUTHWESTERLY SHEAR OVER THE SYSTEM BEING CAUSED BY AN UPPER-LEVEL TROUGH TO THE NORTHWEST. IN FACT...RECENT VISIBLE IMAGES SUGGEST THAT THE CENTER IS PARTIALLY EXPOSED ON THE WESTERN EDGE OF THE MAIN AREA OF CONVECTION. THE U.K MET AND AVN MODELS SUGGEST THAT THE UPPER LEVEL WINDS WILL BECOME MORE FAVORABLE OVER THE NEXT COUPLE OF DAYS...AND THE SHIPS GUIDANCE SHOWS STRENGTHENING TO A HURRICANE. THE OFFICIAL FORECAST IS SIMILAR. THE CENTER CONTINUES TO MEANDER AND THE INITIAL MOTION ESTIMATE IS QUASI-STATIONARY. THE TRACK FORECAST CONTINUES TO BE PROBLEMATIC. THE MID-TROPOSPHERIC TROUGH CURRENTLY MOVING INTO THE EASTERN U.S. DOES NOT APPEAR TO BE INFLUENTIAL ENOUGH TO PICK UP GABRIELLE. THE NCEP GLOBAL...AVN...MODEL SHOWS A RIDGE BUILDING WESTWARD ACROSS THE GREATER ANTILLES OVER THE FORECAST PERIOD...AND THAT MODEL PUSHES THE STORM NORTHWARD AS A RESULT OF SOUTHERLY STEERING ON THE WESTERN SIDE OF THE RIDGE. THE NOGAPS MODEL CONTINUES TO TAKE THE SYSTEM GENERALLY WESTWARD...AND THE U.K. MET OFFICE MODEL CONTINUES TO SHOW LITTLE MOVEMENT. THE CURRENT NHC TRACK FORECAST IS A LITTLE TO THE LEFT OF THE PREVIOUS ONE AND FAIRLY CLOSE TO THE AVN. THE 06Z GFDL RUN IS FARTHER WEST AND SOUTH OF MY TRACK. OBVIOUSLY...THERE IS A GREAT DEAL OF UNCERTAINTY IN THE 48- AND 72-HOUR FORECAST POINTS. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 13/1500Z 25.2N 85.2W 40 KTS 12HR VT 14/0000Z 25.5N 85.5W 45 KTS 24HR VT 14/1200Z 26.0N 85.5W 50 KTS 36HR VT 15/0000Z 27.0N 85.5W 50 KTS 48HR VT 15/1200Z 28.0N 85.0W 65 KTS 72HR VT 16/1200Z 29.5N 83.5W 75 KTS NNNN