Tropical Storm GUILLERMO

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TROPICAL STORM GUILLERMO DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT THU AUG 07 2003
 
VISIBLE...INFRARED...AND MICROWAVE SATELLITE IMAGERY INDICATE THAT 
TROPICAL DEPRESSION SEVEN-E HAS BECOME MUCH BETTER ORGANIZED OVER
THE PAST 6 HOURS. OUTFLOW CONTINUES TO IMPROVE AND A SMALL CENTRAL
DENSE OVERCAST...OR CDO...FEATURE HAS DEVELOPED OVER THE LOW-LEVEL
CENTER. SATELLITE INTENSITY ESTIMATES FROM BOTH TAFB AND SAB ARE
T2.5 PLUS...OR 40 KT...SO THE INITIAL INTENSITY IS SET AT 40 KT AND
THE DEPRESSION IS UPGRADED TO TROPICAL STORM GUILLERMO.
 
THE INITIAL MOTION ESTIMATE IS 280/06. THE MORE SOUTHERLY POSITION
AND SLOWER FORWARD SPEED IS LIKELY A TEMPORARY CONDITION...AND IS
PROBABLY DUE TO THE LOW-LEVEL CENTER RE-ORGANIZING WITHIN THE
CENTRAL DEEP CONVECTION. A GRADUAL INCREASE IN FORWARD SPEED IS
EXPECTED TO RESUME SHORTLY. THE GLOBAL MODELS ARE OF LITTLE USE AS
FAR AS SPECIFIC TRACK FORECAST POSITIONS ARE CONCERNED SINCE THE
MODELS WERE POORLY INITIALIZED AT 07/18Z...AND THEY KILL THE
CYCLONE WITHIN THE NEXT 12 HOURS OR SO AT THE EXPENSE OF SPINNING
UP A SYSTEM TO THE EAST. HOWEVER...THE BASIC SYNOPTIC PATTERN OF
HAVING A STRONG SUBTROPICAL RIDGE TO THE NORTH INDICATES THAT
GUILLERMO SHOULD MOVE IN A GENERAL WEST TO PERHAPS SLIGHTLY
WEST-NORTHWESTWARD DIRECTION THROUGHOUT THE PERIOD. THE OFFICIAL
TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS FORECAST TRACK AND IS
SIMILAR TO THE MEDIUM AND DEEP BAM MODELS THROUGH 36 HOURS...BUT
SLOWER AND WELL SOUTH OF BOTH OF THOSE MODEL TRACKS AFTER THAT.

THE INTENSITY FORECAST WAS INCREASED SIGNIFICANTLY BASED ON THE
STRONGER INITIAL INTENSITY...BUT IT IS STILL SLIGHTLY BELOW THE
SHIPS MODEL WHICH BRINGS THE CYCLONE UP TO 58 KT IN ABOUT 48-60
HOURS...AFTER WHICH IT REMAINS STEADY THROUGH 120 HOURS. IT IS
POSSIBLE THAT GUILLERMO COULD BECOME STRONGER THAN FORECAST AND
EVEN REACH MINIMAL HURRICANE STRENGTH BY 36-48 HOURS GIVEN THAT THE
SHEAR IS EXPECTED TO BE AROUND 10 KT OR LESS AND THE CENTER IS
FORECAST BE VERY CLOSE TO THE 27C SST ISOTHERM. THE 34-KT WIND
RADII WERE ALSO DECREASED SLIGHTLY BASED ON A SLOWER FORWARD SPEED.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/0300Z 16.7N 117.5W    40 KT
 12HR VT     08/1200Z 16.9N 118.7W    45 KT
 24HR VT     09/0000Z 17.2N 120.3W    50 KT
 36HR VT     09/1200Z 17.4N 122.1W    55 KT
 48HR VT     10/0000Z 17.5N 124.0W    55 KT
 72HR VT     11/0000Z 17.5N 127.5W    55 KT
 96HR VT     12/0000Z 17.5N 131.0W    50 KT
120HR VT     13/0000Z 17.5N 135.0W    45 KT
 
 
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