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 674 
 WTNT41 KNHC 040259
 TCDAT1
 HURRICANE FRANCES DISCUSSION NUMBER  41
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 PM EDT FRI SEP 03 2004
  
 RADAR...SATELLITE...RECON DATA...AND NUMEROUS SURFACE REPORTS FROM
 HAM RADIO OPERATORS...SURFACE STATIONS...AND SHIPS IN AND AROUND
 THE CENTRAL AND NORTHWESTERN BAHAMAS...AND THE FLORIDA EAST COAST
 INDICATE THAT FRANCES HAS WEAKENED SINCE THE 18Z ADVISORY. HOWEVER
 ...THE SURFACE PRESSURE IN THE EYE HAS NOT CHANGED FROM 959-960 MB
 SINCE ABOUT 22Z. BRIEF BURSTS OF DEEP CONVECTION HAVE BEEN
 DEVELOPING IN THE NORTHERN SEMICIRCLE WHICH HAVE BEEN HELPING TO
 MAINTAIN A 90-KT INTENSITY.
  
 THE INITIAL MOTION HAS SLOWED TO 295/05. DROPSONDE DATA AND 18Z
 UPPER-AIR DATA INDICATE THE WRAPAROUND MID-LEVEL RIDGE TO THE NORTH
 OF FRANCES HAS NOT MOVED...WITH A HIGH CENTER LOCATED OVER
 SOUTHEAST GEORGIA AND RIDGES EXTENDING EASTWARD AND SOUTHWESTWARD
 FROM THE HIGH FOR SEVERAL HUNDRED MILES. THIS HAS TRAPPED FRANCES
 IN A WEAK STEERING REGIME...WHICH IS EXPECTED TO LAST FOR AT LEAST
 THE NEXT 36 HOURS. AFTER THAT...THE RIDGE OVER THE EASTERN GULF OF
 MEXICO IS FORECAST BY ALL OF THE MODELS TO ERODE SLOWLY EASTWARD
 AND ALLOW FRANCES TO TURN NORTHWESTWARD AND THEN NORTHWARD BY 72
 HOURS. IT IS INTERESTING TO POINT OUT THAT THE GFDL AND GFS MODELS
 THAT PREVIOUSLY FOR SEVERAL DAYS HAD BEEN THE RIGHTMOST OF THE NHC
 MODEL SUITE ARE NOW THE LEFTMOST MODELS...AND TAKE FRANCES ACROSS
 THE NORTHERN PORTION OF LAKE OKEECHOBEE IN ABOUT 36 HOURS. THE
 OFFICIAL TRACK IS SLIGHTLY LEFT OF THE PREVIOUS TRACK AND TO THE
 LEFT OF THE GUNA CONSENSUS MODEL.
 
 SOME WESTERLY WINDS BETWEEN 300-250 MB HAVE BEEN UNDERCUTTING THE
 IMPRESSIVE UPPER-LEVEL OUTFLOW LAYER. THIS UNFAVORABLE SHEAR
 PATTERN...COMBINED WITH MID-LEVEL DRY AIR ENTRAINMENT...HAS LIKELY
 LED TO THE WEAKENING OVER THE PAST 24 HOURS. THE GFS-ETA-GFDL
 MODELS FORECAST THE SHEAR PATTERN TO WEAKEN OR DISAPPEAR IN 18-24
 HOURS...AT ABOUT THE TIME FRANCES IS SLOWLY CROSSING THE WARMER
 GULFSTREAM. HOWEVER...GIVEN THE ALREADY EXPANDED AND LARGE INNER
 CORE WIND FIELD...ONLY SLIGHT INTENSIFICATION IS EXPECTED. THIS
 SCENARIO IS SIMILAR TO THE GFDL INTENSITY FORECAST.
  
 BECAUSE FRANCES IS A SLOW MOVING HURRICANE...IT COULD BRING
 TORRENTIAL RAINS TO PORTIONS OF FLORIDA SATURDAY NIGHT AND SUNDAY.
  
 FORECASTER STEWART
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      04/0300Z 26.1N  77.8W    90 KT
  12HR VT     04/1200Z 26.5N  78.6W    90 KT
  24HR VT     05/0000Z 27.0N  79.8W    95 KT
  36HR VT     05/1200Z 27.6N  81.2W    55 KT...INLAND
  48HR VT     06/0000Z 28.7N  83.1W    35 KT...OVER GULF OF MEXICO
  72HR VT     07/0000Z 31.9N  86.2W    30 KT...INLAND
  96HR VT     08/0000Z 35.0N  87.0W    25 KT...INLAND
 120HR VT     09/0000Z 40.0N  84.5W    20 KT...INLAND
  
  
 $$
 
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