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HURRICANE FLOYD DISCUSSION NUMBER  21
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN SEP 12 1999
 
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT THIS AFTERNOON
REPORTED A MINIMUM CENTRAL PRESSURE OF 940 MB...WHICH REPRESENTS A
DROP OF 20 MB IN ABOUT 12 HOURS.  THE MAXIMUM FLIGHT-LEVEL WINDS
WERE 125 KT.  THE SURFACE WINDS ARE INCREASED TO 110 KT AT THIS
TIME...AND GIVEN THE PRESSURE FALLS...IT IS ONLY A MATTER OF TIME
BEFORE FLOYD BECOMES A CATEGORY FOUR HURRICANE.
 
THE INITIAL MOTION IS ESTIMATED TO BE 280/12...A LITTLE FASTER THAN
EARLIER.  THERE IS LITTLE NEW MODEL GUIDANCE AND THE OFFICIAL
FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS PACKAGE.  A MID-
LEVEL RIDGE NORTH OF THE CYCLONE WILL KEEP FLOYD ON A WEST TO WEST-
NORTHWEST TRACK FOR THE NEXT DAY OR SO.  BEYOND THAT...THE
MID-ATLANTIC RIDGE IS FORECAST TO WEAKEN AS A MAJOR MID-LATITUDE
TROUGH OVER THE U.S. APPROACHES.  THE CENTER OF THE HURRICANE IS
EXPECTED TO BE VERY CLOSE TO THE FLORIDA COAST IN 72 HOURS.  THE 12Z
UKMET...AND THE GFDL RUN OFF THE NAVY NOGAPS MODEL SHOWS FLOYD
REMAINING OFF THE COAST.

WIND RADII HAVE BEEN EXPANDED BASED ON A SURFACE ANALYSIS PROVIDED
BY THE NOAA HURRICANE RESEARCH DIVISION.  BASED ON THESE RADII AND
THE FORECAST TRACK...A HURRICANE WATCH MAY BE REQUIRED FOR A PORTION
OF THE FLORIDA COAST LATER TONIGHT OR EARLY TOMORROW.

TWO NOAA AIRCRAFT ARE CURRENTLY FLYING IN THE ENVIRONMENT OF
FLOYD...TO HELP INITIALIZE THE 00Z GLOBAL MODELS.
 
FRANKLIN

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     12/2100Z 23.4N  68.2W   110 KTS
12HR VT     13/0600Z 23.8N  70.1W   120 KTS
24HR VT     13/1800Z 24.4N  72.7W   120 KTS
36HR VT     14/0600Z 25.2N  75.2W   120 KTS
48HR VT     14/1800Z 26.5N  77.5W   120 KTS
72HR VT     15/1800Z 29.0N  81.0W   120 KTS...INLAND
 
 
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