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HURRICANE FELIX DISCUSSION NUMBER  28
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT SEP 15 2001
 
FELIX HAS CHANGED LITTLE DURING THE PAST 6 HOURS.  CENTRAL DEEP 
CONVECTION HAS PERSISTED AROUND THE LOW-LEVEL CIRCULATION...
ALBEIT MUCH SMALLER IN AREAL COVERAGE NOW.  UPPER-LEVEL OUTFLOW 
REMAINS QUITE IMPRESSIVE AND VERY SYMMETRICAL.  AT 15/1500Z... 
DRIFTING BUOY 41644 REPORTED A PRESSURE OF 975.8 MB IN THE NORTHWEST 
QUADRANT OF THE SATELLITE-INDICATED EYE...SO THE PRESSURE HAS BEEN 
INCREASED TO 975 MB AND THE INTENSITY DECREASED TO 85 KT.
 
THE INITIAL MOTION IS 075/16. THERE IS NO SIGNIFICANT CHANGE TO THE 
PREVIOUS FORECAST TRACK OR REASONING.  FELIX SHOULD CONTINUE TO MOVE 
EAST-NORTHEASTWARD FOR THE NEXT 12 HOURS OR SO AS IT TRACKS AROUND 
THE SOUTHERN PERIPHERY OF THE LARGE AND VERTICALLY DEEP TROPOSPHERIC 
LOW PRESSURE SYSTEM LOCATED NORTHWEST OF THE AZORES ISLANDS.  DURING 
THE PAST 6 HOURS...THE DEEP LOW TO THE NORTH OF FELIX HAS BEGUN TO 
TURN MORE TOWARD THE NORTH AND WEAKEN.  THE GLOBAL MODELS APPEAR TO 
HAVE AN EXCELLENT HANDLE ON THE SYNOPTIC PATTERN...AND THEIR 
FORECAST TRACKS ARE ALMOST ON TOP OF EACH OTHER THROUGH 36 HOURS.  
HOWEVER...AFTER THAT THE MODELS BEGIN TO DIVERGE SIGNIFICANTLY. 
NOGAPS AND THE UKMET MODELS SLOW DOWN FELIX IN 24 HOURS AND MAKE THE 
CYCLONE NEARLY STATIONARY IN 48 HOURS ABOUT 180 NM SOUTHWEST OF THE 
AZORES...AND THEN TURN THE SYSTEM SLOWLY SOUTHWARD AFTER THAT.  THE 
AVN MODEL CONTINUES TO TAKE FELIX NORTHEASTWARD THROUGH THE PERIOD 
TO A POSITON ABOUT 60 NM SOUTH OF LAJES IN 72 HOURS.  THE GFDL MODEL 
TAKES FELIX TO THE NORTHEAST AND THEN ACTUALLY TURNS THE CYCLONE 
BACK TO THE SOUTHWEST ALMOST ON TOP OF ITS PREVIOUS 36 HOUR FORECAST 
TRACK.  THE SCENARIO FORECAST BY THE GFDL SEEMS UNREASONABLE BASED 
ON ALL THREE GLOBAL MODELS FORECASTING MODERATE WEST TO 
NORTHWESTERLY MID- TO UPPER-LEVEL FLOW TO DEVELOP ACROSS THE CYCLONE 
BY 72 HOURS. THE AVN FORECAST TRACK WAS CLOSELY FOLLOWED GIVEN ITS 
EXCELLENT CURRENT RUNNING ERRORS OF LESS THAN 75 NM AT ALL FORECAST 
TIMES WITH FELIX.
 
ONLY SLOW WEAKENING IS FORECAST SINCE THE UPPER-LEVEL SHEAR IS 
EXPECTED TO REMAIN AROUND 15-20 KT THROUGHOUT THE PERIOD...AND SSTS 
ARE WILL BE ABOVE 25C FOR THE NEXT 36 HOURS.  HOWEVER...IF FELIX 
SLOWS DOWN MORE THAN INDICATED BY THE OFFICIAL FORECAST TRACK...THEN 
THE CYCLONE WOULD LIKELY WEAKEN TO MUCH LESS THAN 60-KT AT 72 HOURS 
SINCE SSTS ARE ONLY ABOUT 23-24C IN THE VICINITY OF THE AZORES 
ISLANDS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     15/2100Z 32.3N  36.8W    85 KTS
12HR VT     16/0600Z 32.9N  34.4W    80 KTS
24HR VT     16/1800Z 34.2N  32.0W    75 KTS
36HR VT     17/0600Z 35.5N  30.5W    70 KTS
48HR VT     17/1800Z 36.4N  29.6W    65 KTS
72HR VT     18/1800Z 37.3N  28.0W    60 KTS
 
 
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