Hurricane HERNAN

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HURRICANE HERNAN DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092008
800 AM PDT MON AUG 11 2008
 
OVER THE PAST SIX HOURS OR SO...DEEP CONVECTION AROUND THE CENTER OF
HERNAN HAS CONTRACTED IN AREA AND THE EYE HAS CONTINUED TO FILL
WITH CLOUDS. DVORAK DATA T-NUMBERS ARE 4.0 AND 4.5 FROM TAFB AND
SAB... RESPECTIVELY...SO THE INITIAL INTENSITY WILL BE MAINTAINED
AT 70 KT AS A CONSENSUS OF THESE NUMBERS. HERNAN IS NOW OVER COOL
SEA SURFACE TEMPERATURES NEAR 24C BUT THE POWERFUL CIRCULATION HAS
CAUSED THE SYSTEM TO BE SOMEWHAT RESISTANT TO A RAPID DECAY. IN
ADDITION...THE FORECAST TRACK TAKES HERNAN WEST-SOUTHWEST PARALLEL
TO THE STRONG SST GRADIENT SO ONLY GRADUAL WEAKENING IS FORECAST
OVER THE NEXT 48 HOURS IN LINE WITH SHIPS AND THE INTENSITY
CONSENSUS. THERE IS A POSSIBILITY THAT HERNAN COULD MAINTAIN
TROPICAL CYCLONE STATUS THROUGH DAYS 4 AND 5 EVEN THOUGH THE
OFFICIAL FORECAST CALLS FOR WEAKENING TO A REMNANT LOW.
 
HERNAN HAS BEEN ON A SHORT-TERM TRACK JUST SLIGHTLY NORTH OF THE
PREVIOUS FORECAST WITH AN INITIAL MOTION OF 285/9. HERNAN IS
APPROACHING A MIDDLE TO UPPER-LEVEL TROUGH NORTHEAST OF HAWAII AND
IS LOCATED NEAR AN AREA OF LOW PRESSURE NEAR 16N143W...BOTH OF
WHICH MAY BE CONTRIBUTING TO THE RECENT NORTHWESTWARD MOTION. ONCE
THE CYCLONE BEGINS ITS WEAKENING TREND...A SOUTHWESTWARD TURN IS
EXPECTED TO COMMENCE AS THE CIRCULATION IS STEERED BY THE LOW-LEVEL
RIDGE. HERNAN IS EXPECTED TO CROSS INTO THE CENTRAL PACIFIC BASIN
SOMETIME ON THURSDAY.
 
WIND RADII HAVE BEEN CONTRACTED BASED ON AN EXCELLENT 0620 UTC ASCAT
PASS COVERING MOST OF HERNAN'S CIRCULATION.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1500Z 19.0N 130.2W    70 KT
 12HR VT     12/0000Z 19.0N 131.2W    60 KT
 24HR VT     12/1200Z 18.6N 132.7W    50 KT
 36HR VT     13/0000Z 18.2N 134.2W    40 KT
 48HR VT     13/1200Z 17.7N 135.7W    35 KT
 72HR VT     14/1200Z 16.5N 139.0W    30 KT
 96HR VT     15/1200Z 15.5N 143.0W    25 KT...REMNANT LOW
120HR VT     16/1200Z 15.5N 147.0W    25 KT...REMNANT LOW
 
$$
FORECASTER BERG/PASCH
 
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