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HURRICANE HERNAN DISCUSSION NUMBER  15
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT MON SEP 02 2002

HERNAN IS STILL AN IMPRESSIVE HURRICANE DESPITE THE EYEWALL 
REPLACEMENT CYCLE THAT IT HAS BEEN UNDERGOING. THE INITIAL INTENSITY 
OF 100 KT IS BASED ON A BLEND OF DVROAK CURRENT INTENSITY ESTIMATES 
OF 90 KT... OR T5.0...FROM ALL THREE AGENCIES AND 3-HOUR OBJECTIVE 
CURRENT INTENSITY ESTIMATES OF T5.7...OR 105 KT.
 
THE INITIAL MOTION ESTIMATE IS 290/09. IT APPEARS THAT HERNAN MAY 
HAVE RETURNED TO ITS PREVIOUS BASE COURSE OF 290 DEGREES. HOWEVER... 
THE CONCENTRIC EYEWALL PATTERN...AS SEEN IN MICROWAVE SATELLITE 
DATA...MAY RESULT IN A SOME WOBBLING ABOUT A MEAN WEST-NORTHWEST 
TRACK FOR ANOTHER 6 TO 12 HOURS. THE NHC MODEL GUIDANCE REMAINS 
CONSISTENT WITH TAKING HERNAN GRADUALLY NORTHWEST AND NORTHWARD 
AROUND THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE BY 48 
HOURS...AND THEN RECURVING IT TO THE NORTHEAST BY 72 HOURS. THE 
OFFICIAL TRACK IS JUST AN UPDATE OF THE PREVIOUS FORECAST TRACK AND
CLOSE TO THE AVN...AVN ENSEMBLE...AND GFDL MODELS.
 
HERNAN IS EXPECTED TO CONTINUE TO WEAKEN THROUGHOUT THE PERIOD AS IT
MOVES OVER COOLER SSTS AND ENCOUNTERS INCREASING SOUTHWESTERLY
UPPER-LEVEL SHEAR.  THE OFFICIAL INTENSITY FORECAST SHOWS A FASTER
WEAKENING TREND THAN THE PREVIOUS FORECAST...BUT NOT AS FAST AS THE
SHIPS MODEL WHICH DISSIPATES THE CYCLONE BY 72 HOURS.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     02/2100Z 18.8N 116.8W   100 KTS
12HR VT     03/0600Z 19.2N 118.3W    90 KTS
24HR VT     03/1800Z 20.3N 120.2W    80 KTS
36HR VT     04/0600Z 21.5N 121.9W    70 KTS
48HR VT     04/1800Z 22.8N 123.2W    55 KTS
72HR VT     05/1800Z 25.5N 124.0W    35 KTS
 
 
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