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HURRICANE HERNAN DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT MON SEP 02 2002
 
HERNAN CONTINUES ON A WEAKENING TREND AS EVIDENCED BY WARMING OF THE 
CONVECTION SURROUNDING THE EYE.  LATEST DVORAK INTENSITY ESTIMATES 
ARE 5.0 FROM TAFB AND SAB...AND 5.5 FROM AFWA...AND 3-HOUR OBJECTIVE 
DATA T-NUMBERS ARE NEAR 5.0.  THEREFORE...THE INITIAL INTENSITY WILL 
BE DECREASED TO 95 KT FOR THIS FORECAST PACKAGE.  A RECENT TRMM 
OVERPASS FROM 2238 UTC SUGGESTS THAT AN OUTER EYE WALL MAY BE TRYING 
TO FORM...WHICH WOULD COMPLETE THE EYEWALL REPLACEMENT CYCLE THAT 
BEGAN ABOUT 24 HOURS AGO.  ARRESTED WEAKENING OR RESTRENGTHENING 
TYPICALLY OCCURS WITH EYEWALL REPLACEMENT CYCLES...ALTHOUGH IN 
THIS CASE HERNAN MAY NOT HAVE ENOUGH TIME TO STRENGTHEN 
SIGNIFICANTLY DUE TO ITS EXPECTED PASSING OVER SUB-26C SEA SURFACE 
TEMPERATURES IN ABOUT 12-24 HOURS.  TO ACCOUNT FOR THE POSSIBILITY 
OF RESTRENGTHENING...THE WEAKENING TREND WILL BE SLOWED DOWN FOR THE 
FIRST 12 HOURS...WITH MORE RAPID WEAKENING THEREAFTER AS INDICATED 
BY THE SHIPS MODEL AND ALSO BY THE PREVIOUS FORECAST.

THE INITIAL MOTION IS 285/10 WHICH IS SLIGHTLY TO THE SOUTH OF THE
PREVIOUS TRACK...HOWEVER THE TRACK FORECAST PHILOSOPHY REMAINS
MOSTLY UNCHANGED.  HERNAN WILL MAINTAIN A WEST-NORTHWEST TRACK FOR
ABOUT 12-24 HOURS BEFORE MAKING A GRADUAL TURN TO THE NORTHWEST AND
THEN NORTH BY THE END OF THE FORECAST PERIOD AS THE CYCLONE BECOMES
INFLUENCED BY A DEVELOPING MID/UPPER LEVEL TROUGH OFF THE CALIFORNIA
COAST.  THIS TRACK IS AN UPDATE OF THE PREVIOUS FORECAST AND IN
CLOSE AGREEMENT WITH MUCH OF THE NHC GUIDANCE.

FORECASTER JARVINEN/MOLLEDA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     03/0300Z 18.9N 117.8W    95 KTS
12HR VT     03/1200Z 19.5N 119.3W    90 KTS
24HR VT     04/0000Z 20.7N 120.8W    75 KTS
36HR VT     04/1200Z 22.0N 122.2W    65 KTS
48HR VT     05/0000Z 23.5N 123.5W    50 KTS
72HR VT     06/0000Z 26.0N 124.0W    30 KTS
 
 
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