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 322 
 WTNT41 KNHC 261447
 TCDAT1
 TROPICAL STORM FRANCES DISCUSSION NUMBER   7
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 AM EDT THU AUG 26 2004
  
 FRANCES HAS BECOME MUCH BETTER ORGANIZED DURING THE PAST 12 HOURS...
 AS NOTED BY THE TIGHT COILING OF BOTH THE INNER AND OUTER
 CONVECTIVE BANDS...AND AN OCCASIONAL HINT OF A BANDING EYE FEATURE.
 A DVORAK SATELLITE INTENSITY ESTIMATE OF T3.5 WAS OBTAINED FROM
 BOTH TAFB AND SAB. HOWEVER...BANDING FEATURES AND INNER-CORE
 CONVECTION HAVE IMPROVED SINCE THE 12Z FIXES...SO I HAVE CONTINUED
 THE TREND FROM THE PREVIOUS ADVISORY OF GOING SLIGHTLY HIGHER THAN
 THE SATELLITE ESTIMATES ARE INDICATING. UPPER-LEVEL OUTFLOW IS GOOD
 IN ALL QUADRANTS AND IS BECOMING MORE CIRCULAR.
  
 THE INITIAL MOTION REMAINS 290/15. FRANCES HAS BASICALLY REMAINED ON
 TRACK THE PAST 24 HOURS. HOWEVER...THE NHC MODEL GUIDANCE IS NOT IN
 GOOD AGREEMENT AFTER 36 HOURS. THE NOGAPS...UKMET...AND ECMWF TAKE
 FRANCES MORE NORTHWESTWARD THOUGHOUT THE FORECAST PERIOD...WHEREAS
 THE GFDL...GFS...AND THE CANADIAN MODELS TAKE THE CYCLONE MORE
 WEST-NORTHWESTWARD AND EVEN WESTWARD. THE MAIN DIFFERENCES LIE IN
 HOW MUCH EROSION OF THE SUBTROPICAL RIDGE OCCURS NORTH OF FRANCES
 IN 36-72 HOURS AS A LARGE EXTRATROPICAL LOW OFF THE CANADIAN
 MARITIMES DIGS SOUTHWARD. THE UKMET AND NOGAPS MODEL SHOW MORE
 EROSION OF THE RIDGE...WHILE THE GFS...GFDL...AND CANADIAN MODELS
 LIFT OUT THE UPPER-LOW MORE QUICKLY...WHICH ALLOWS THE RIDGE TO
 BUILD BACK WESTWARD TO THE NORTH OF THE CYCLONE AFTER 72 HOURS. THE
 PAST 24 HOUR TREND IN WATER VAPOR IMAGERY SUGGESTS THAT THE
 UPPER-LOW HAS PROBABLY PUSHED ABOUT AS FAR SOUTH AS IT CAN...WHICH
 WOULD SUPPORT THE GFS-GFDL-CANADIAN SCENARIO OF A MORE WESTWARD
 TRACK BY 96 HOURS. THE PAST 4 GFDL RUNS HAVE SUCCESSIVELY SHIFTED
 THE TRACK MORE WESTWARD WITH EACH RUN...WHILE THE GFS HAS A LEFT OF
 TRACK BIAS. THEREFORE...THE OFFICIAL TRACK WAS SHIFTED SLIGHTLY
 LEFT OF THE PREVIOUS FORECAST AND LEFT OF THE LATEST GFDL RUN...BUT
 NOT AS FAR WEST OR AS FAST AS THE GFS AND CANADIAN MODELS.
 
 FRANCES MAY BE ON A FAST-TRACK IN ITS DEVELOPMENT PROCESS...BUT I
 WOULD PREFER TO WAIT AND SEE IF ANY DRY AIR ON THE EAST SIDE GETS
 WRAPPED INTO THE CENTER.  HOWEVER...IF A DISTINCT EYE APPEARS LATER
 TODAY...THEN RAPID INTENSIFICATION...AND ALSO MAKING FRANCES A
 MAJOR HURRICANE IN 48-72 HOURS LIKE THE GFDL AND SHIPS MODELS ARE
 INDICATING...WILL HAVE TO BE CONSIDERED ON THE NEXT ADVISORY.
  
 FORECASTER STEWART
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      26/1500Z 13.1N  45.0W    60 KT
  12HR VT     27/0000Z 14.0N  47.0W    70 KT
  24HR VT     27/1200Z 15.2N  49.2W    80 KT
  36HR VT     28/0000Z 16.4N  51.1W    90 KT
  48HR VT     28/1200Z 17.5N  52.3W    95 KT
  72HR VT     29/1200Z 18.6N  54.0W    95 KT
  96HR VT     30/1200Z 20.0N  57.0W    95 KT
 120HR VT     31/1200Z 21.0N  61.0W    95 KT
  
  
 $$
 
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