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HURRICANE FLOYD DISCUSSION NUMBER  23
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT MON SEP 13 1999
 
FLOYD HAS CONTINUED TO INTENSIFY THIS MORNING WITH THE LATEST AIR
FORCE RESERVE HURRICANE HUNTER AIRCRAFT REPORTING A MINIMUM CENTRAL
PRESSURE OF 922 MB...A 39 MB DROP OVER THE LAST 24 HRS. THE MAXIMUM
FLIGHT-LEVEL WIND...700 MB...WAS 146 KTS IN THE NORTHWEST QUADRANT
WHILE DROPSONDE DATA SHOW A MAXIMUM WIND OF 168 KTS. THUS...THE
INITIAL INTENSITY IS INCREASED TO 135 KTS FOR THIS ADVISORY WHICH
MAKES FLOYD A STRONG CATEGORY 4 HURRICANE.
 
SATELLITE IMAGERY DEPICTS A CLASSIC HURRICANE WITH AN EXTREMELY
WELL-DEFINED EYE AND THE UPPER TROPOSPHERIC OUTFLOW IS IMPRESSIVE.
THERE HAS BEEN AN EROSION OF THE COLD CLOUD TOPS OVER THE WESTERN
SEMICIRCLE OF FLOYD. HOWEVER...THIS MAY BE A TEMPORARY CONDITION.
SST ANALYSES FROM JOHN HOPKINS UNIVERSITY INDICATE THAT FLOYD IS
TRAVERSING A WARM EDDY...ABOUT 32C.  THERE WILL LIKELY BE SOME
FLUCTUATIONS IN INTENSITY OVER THE NEXT 12-24 HRS...MAINLY DUE 
TO EYE-WALL REPLACEMENT CYCLES.

THE INITIAL MOTION ESTIMATE REMAINS 280/12. THE SYNOPTIC REASONING
BEHIND THE TRACK FORECAST REMAINS UNCHANGED WITH FLOYD BEING
STEERING BY THE MID-TROPOSPHERIC ANTICYCLONE OVER THE EXTREME
WESTERN ATLANTIC...AS DEPICTED BY THE NOAA P-3 AND G-IV SYNOPTIC
SURVEILLANCE MISSION DATA. THE 00Z OBJECTIVE GUIDANCE SHOWS A
TIGHTER CLUSTERING AROUND A WEST TO WEST-NORTHWEST MOTION THROUGH
36 HRS...LIKELY ATTRIBUTABLE TO THE NOAA DATA.  THEREAFTER...THE
GUIDANCE BECOMES MORE DIVERGENT WITH THE BAM MODELS TRACKING FLOYD
INTO PALM BEACH FLORIDA...THE AVIATION NEAR JACKSONVILLE...WHILE 
THE GLOBAL MODELS AND THE GFDL TURN THE SYSTEM NORTHWARD OVER THE
NORTHWEST BAHAMAS AND INDICATE LANDFALL IN THE SOUTH CAROLINA.
 
THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO THE LEFT OF THE
PREVIOUS ADVISORY OWNING TO THE CONTINUED WESTERLY MOTION. BASED 
ON THIS TRACK...A HURRICANE WATCH IS BEING ISSUED FOR THE FLORIDA
EAST COAST FROM SOUTH OF FLAGLER BEACH TO HALLANDALE. THE GOVERNMENT
OF THE BAHAMAS IS ISSUING A HURRICANE WARNING FOR THE NORTHWEST
BAHAMAS.  ALL INTERESTS ELSEWHERE ALONG THE FLORIDA EAST COAST...
AND THE SOUTHEAST COAST OF THE U.S. SHOULD CLOSELY MONITOR THE
PROGRESS OF THIS DANGEROUS HURRICANE. 

GUINEY
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/0900Z 23.7N  70.6W   135 KTS
12HR VT     13/1800Z 24.1N  72.6W   135 KTS
24HR VT     14/0600Z 24.8N  75.0W   135 KTS
36HR VT     14/1800Z 25.8N  77.2W   135 KTS
48HR VT     15/0600Z 27.5N  79.0W   130 KTS
72HR VT     16/0600Z 31.0N  81.0W   125 KTS
 
 
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