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TROPICAL STORM HERNAN DISCUSSION NUMBER  25
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT THU SEP 05 2002
 
HERNAN CONTINUES TO WEAKEN WITH AN OVERALL DECREASE IN CLOUD TOP 
TEMPERATURES. HOWEVER...SOME NEW BANDS OF MODERATE CONVECTION HAVE 
FORMED TO THE SOUTH AND WEST OF THE CENTER. CURRENT DVORAK INTENSITY 
ESTIMATES ARE 30 KTS FROM TAFB AND 35 KNOTS FROM SAB AND AFWA. THE 
INITIAL INTENSITY IS LOWERED FROM THE PREVIOUS ADVISORY TO 35 KNOTS. 
DESPITE THE WEAKENING TREND...UPPER LEVEL OUTFLOW REMAINS GOOD.   

THE INITIAL MOTION ESTIMATE IS 310/5.  HERNAN HAS CONTINUED TO SLOW 
ITS FORWARD SPEED AS IT BECOMES AN INCREASINGLY SHALLOW SYSTEM.   
THE DOMINANT STEERING FLOW IS NOW THE LOW LEVEL EASTERLIES ON THE 
SOUTHERN EXTENT OF THE SUBTROPICAL RIDGE.  THE OFFICIAL FORECAST 
TRACK IS SOUTH OF THE PREVIOUS TRACK AND IS IN BEST AGREEMENT WITH 
THE UKMET GLOBAL MODEL AND IS SIMILAR TO THE AVN..NOGAPS...AND GFDL 
WHICH INDICATE A DRIFT TO THE SOUTHWEST. 

HERNAN IS FORECAST TO CONTINUE WEAKENING AS IT REMAINS OVER 
RELATIVELY COOL WATER. HOWEVER...THE FAVORABLE UPPER LEVEL OUTFLOW 
PATTERN AND THE WESTWARD TRACK SHOULD KEEP THE SYSTEM IN A LESS 
HOSTILE ENVIRONMENT THAN PREVIOUSLY EXPECTED. THE INTENSITY FORECAST 
IS A LITTLE HIGHER THAN THE SHIPS INTENSITY MODEL...WHICH DISSIPATES 
HERNAN BY 24 HOURS.  HOWEVER...IF HERNAN TAKES A MORE SOUTHWARD 
TRACK AS INDICATED BY THE AVN...NOGAPS...AND GFDL MODELS...THEN  
WEAKENING WILL NOT BE AS FAST AS CURRENTLY FORECAST.  
 
FORECASTER STEWART/RHOME
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     05/0900Z 22.1N 123.9W    35 KTS
12HR VT     05/1800Z 22.5N 124.4W    30 KTS
24HR VT     06/0600Z 22.8N 125.1W    25 KTS
36HR VT     06/1800Z 23.0N 126.0W    25 KTS...DISSIPATING
48HR VT     07/0600Z 23.0N 126.8W    20 KTS...REMNANT LOW
72HR VT     08/0600Z 22.5N 128.5W    20 KTS...REMNANT LOW
 
 
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