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ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM HURRICANE GERT DISCUSSION NUMBER 23 NATIONAL WEATHER SERVICE MIAMI FL 11 PM EDT THU SEP 16 1999 THERE HAVE BEEN NO RECONNAISSANCE DATA SINCE ABOUT 20Z. AT THAT TIME PEAK FLIGHT LEVEL WINDS WERE 127 KT...THIS SUPPORTS A SURFACE WIND OF 115 KT. DROPSONDES IN THE NORTHEAST AND NORTHWEST QUADRANTS OF THE EYEWALL REPORTED SURFACE WINDS OF ABOUT 85 AND 110 KT RESPECTIVELY. SATELLITE CLASSIFICATIONS FROM TAFB AND SAB ARE 127 AND 115 KT. THE OFFICIAL INTENSITY IS HELD AT 115 KT FOR THIS PACKAGE...AND ANOTHER AIRCRAFT WILL BE IN THE CYCLONE AT 06Z. THERE IS NO SHIPS INTENSITY MODEL RUN FOR THIS CYCLE...BUT THE SPREAD OF THE BAM MODELS SUGGESTS LOW SHEAR OVER THE NEXT THREE DAYS. WATER TEMPERATURES REMAIN WARM SO THE CURRENT INTENSITY IS MAINTAINED THROUGHOUT THE FORECAST PERIOD...ALTHOUGH FLUCTUATIONS IN INTENSITY ASSOCIATED WITH INNER CORE/EYEWALL DYNAMICS ARE TO BE EXPECTED. WIND RADII HAVE BEEN SUBSTANTIALLY ADJUSTED BASED ON THE LATEST RECON DATA. THE INTIAL MOTION REMAINS 300/9. THERE HAS BEEN A NOTICEABLE SHIFT IN THE GUIDANCE...WITH ALL MODELS DEPENDENT ON THE AVN SHOWING A LEFTWARD TURN AT THE END OF THE PERIOD. ONCE AGAIN...THE AVN IS HAVING SEVERE PROBLEMS INITIALIZING THE VORTEX...AND THIS APPEARS TO LEAD TO THE DEVELOPMENT OF A MID-LEVEL TROUGH TO THE SOUTHWEST OF THE CYCLONE. THE NOGAPS AND THE UKMET TRACKS DO NOT HAVE THE LEFT TURN. THERE ARE TWO GFDL RUNS...ONE RUN OFF THE NOGAPS...GFNI...AND ONE OFF THE AVN...GFDI. ONLY THE GFDI SHOWS THE TURN. I AM NOT READY TO BITE ON THIS GUIDANCE AND MAINTAIN A SLOWLY RECURVING TRACK THAT IS HALFWAY BETWEEN THE UKMET AND GFNI. ON THIS TRACK BERMUDA IS A POTENTIAL TARGET IN ABOUT 4 DAYS. THE MAXIMUM WINDS IN THE PUBLIC ADVISORY ARE SET TO 135 MPH FOR CONSISTENCY IN THE SAFFIR-SIMPSON SCALE. FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 17/0300Z 19.4N 54.6W 115 KTS 12HR VT 17/1200Z 20.1N 55.8W 115 KTS 24HR VT 18/0000Z 21.5N 57.4W 115 KTS 36HR VT 18/1200Z 22.8N 58.7W 115 KTS 48HR VT 19/0000Z 24.5N 60.0W 115 KTS 72HR VT 20/0000Z 28.0N 62.0W 115 KTS NNNN