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HURRICANE HERNAN DISCUSSION NUMBER  21
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT WED SEP 04 2002
 
HERNAN CONTINUES TO WEAKEN AS IT MOVES OVER COOLER WATER.  TOPS HAVE
CONTINUED TO WARM DURING THE NIGHT WITH THE ONLY REMAINING
CONVECTION NOW LOCATED OVER THE WESTERN SEMICIRCLE.  DVORAK
INTENSITY ESTIMATES FROM THE SATELLITE AGENCIES OF BOTH TAFB AND SAB
ARE 4.0...WITH A 3 HOUR AVERAGE OBJECTIVE T-NUMBER OF 4.1.  THE
INITIAL INTENSITY WILL BE LOWERED SLIGHTLY TO 65 KT FOR THIS
FORECAST PACKAGE.  THE WEAKENING TREND WILL CONTINUE AS HERNAN MOVES
OVER PROGRESSIVELY COOLER WATER...AS WELL AS INTO INCREASING
WESTERLY SHEAR AHEAD OF AN APPROACHING MID/UPPER LEVEL TROUGH LATE
IN THE FORECAST PERIOD. HERNAN IS FORECAST TO DISSIPATE BY 72 HOURS.

HERNAN IS MOVING 295 DEGREES AT ABOUT 9 KNOTS. A GRADUAL TURN TO THE
NORTHWEST IS EXPECTED WITHIN THE NEXT 24 HOURS AS HERNAN NEARS THE
WESTERN EDGE OF THE SUBTROPICAL RIDGE. INCREASING WESTERLY SHEAR AND 
COLD SSTS ARE EXPECTED TO RAPILDY WEAKEN THE CYCLONE BY 36 TO 48 
HOURS. HOWEVER...THE LOW-LEVEL AND UPPER-LEVEL CIRCUALTIONS MAY 
DECOUPLE SOONER THAN FORECAST...WHICH MAY RESULT IN A REMNANT 
NON-CONVECTIVE LOW POSSIBLY BECOMING STATIONARY NEAR THE 48 HOUR 
FORECAST POSITION.
 
FORECASTER STEWART/AGUIRRE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     04/0900Z 20.5N 122.0W    65 KTS
12HR VT     04/1800Z 21.3N 123.1W    60 KTS
24HR VT     05/0600Z 22.3N 124.0W    50 KTS
36HR VT     05/1800Z 23.3N 124.6W    40 KTS
48HR VT     06/0600Z 24.7N 124.6W    30 KTS
72HR VT     07/0600Z 26.5N 124.4W    25 KTS...DISSIPATING
 
 
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