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HURRICANE HERNAN DISCUSSION NUMBER  12
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT SUN SEP 01 2002
 
LATEST SATELLITE DATA INDICATE THAT HERNAN HAS WEAKENED SOME DURING
THE PAST FEW HOURS.  CONVECTION SURROUNDING THE EYE HAS WARMED...
WHILE THE EYE ITSELF HAS COOLED A BIT.  DVORAK INTENSITY ESTIMATES
FROM THE SATELLITE AGENCIES REFLECT THIS WEAKENING TREND WITH
T-NUMBERS RANGING FROM 5.5 TO 6.5...AND THE INITIAL INTENSITY WILL
BE REDUCED TO 135 KT.  THIS WEAKENING MAY BE DUE TO AN EYEWALL
REPLACEMENT CYCLE...NOT UNCOMMON FOR HURRICANES OF THIS MAGNITUDE.
INDEED...A RECENT SSMI OVERPASS AT 0134 UTC STRONGLY SUGGESTS A
DOUBLE EYEWALL STRUCTURE...THEREFORE SOME FLUCTUATIONS IN INTENSITY 
MAY OCCUR FOR THE NEXT 12-24 HOURS BEFORE HERNAN ENCOUNTERS COOLER 
WATERS IN ABOUT 36 HOURS AND BEGINS TO WEAKEN.

THE INITIAL MOTION IS 290/12...AND THIS WEST-NORTHWEST TRACK SHOULD 
CONTINUE FOR THE NEXT DAY OR TWO AS A DEEP LAYER MEAN RIDGE PERSISTS 
NORTH OF THE CYCLONE.  AFTER 48 HOURS OR SO...HERNAN IS FORECAST TO 
MAKE A GRADUAL TURN TO THE NORTHWEST AND NORTH AS THE CYCLONE 
REACHES THE WESTERN PERIPHERY OF THE RIDGE AND RESPONDS TO A 
DEVELOPING MID/UPPER LEVEL TROUGH OFF THE CALIFORNIA COAST.  THE 
OFFICIAL TRACK IS BASICALLY AN UPDATE OF THE PREVIOUS FORECAST AND 
IS IN GOOD AGREEMENT WITH THE GUIDANCE SUITE.
 
FORECASTER JARVINEN/MOLLEDA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     02/0300Z 18.1N 114.0W   135 KTS
12HR VT     02/1200Z 18.7N 115.7W   130 KTS
24HR VT     03/0000Z 19.4N 117.8W   130 KTS
36HR VT     03/1200Z 20.1N 119.8W   120 KTS
48HR VT     04/0000Z 21.0N 121.5W   105 KTS
72HR VT     05/0000Z 23.0N 124.0W    75 KTS
 
 
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