Tropical Storm GUILLERMO

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TROPICAL DEPRESSION GUILLERMO DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT MON AUG 11 2003

ADVISORY RE-TRANSMITTED DUE TO NETWORK COMMUNICATIONS PROBLEMS
 
THE CONVECTIVE BURST SEEN DURING THE MORNING HAS WEAKENED...LEAVING
GUILLERMO AS A SWIRL OF LOW/MID-LEVEL CLOUDS WITH A FEW
THUNDERSTORMS IN A RAGGED BAND WEST OF THE CENTER.  THE INITIAL
INTENSITY REMAINS 30 KT BASED ON SATELLITE INTENSITY ESTIMATES FROM
TAFB AND AFWA...ALONG WITH A RECENT SSM/I OVERPASS.
 
THE INITIAL MOTION REMAINS 275/13.  THE CYCLONE IS CURRENTLY ON THE
SOUTH SIDE OF A STRONG SUBTROPICAL RIDGE.  LARGE-SCALE MODELS
FORECAST THE RIDGE TO WEAKEN SOMEWHAT TO THE NORTH AND EAST OF
GUILLERMO AS A MID/UPPER-LEVEL WESTERLY TROUGH DIGS SOUTHWARD
DURING THE FIRST 24-48 HR.  GUILLERMO IS TOO FAR SOUTHWEST TO BE
PICKED UP BY THE TROUGH...SO THE MOST LIKELY SCENARIO IS CONTINUED
WESTWARD MOTION AT A SLOWER FORWARD SPEED.  NHC TRACK GUIDANCE HAS
SPREAD IN BOTH DIRECTION...BETWEEN NORTHWEST AND SOUTHWEST...AND
SPEED.  THE OFFICIAL FORECAST...WHICH IS AN UPDATE OF THE PREVIOUS
PACKAGE...IS DOWN THE MIDDLE OF THE GUIDANCE.
 
THE FORECAST TRACK KEEPS GUILLERMO OVER 25C-26C SEA SURFACE
TEMPERATURES...SO THE INTENSITY FORECAST IS DEPENDENT MAINLY ON THE
VERTICAL SHEAR.  THE CANADIAN MODEL FORECASTS STRONG UPPER-LEVEL
WESTERLIES ALONG THE PATH OF THE CYCLONE...WHILE THE UKMET...THE
NOGAPS...AND NOW THE GFS...HAVE A SOMEWHAT MORE FAVORABLE
ENVIRONMENT. THE INTENSITY FORECAST WILL SOMEWHAT COMPROMISE
BETWEEN THESE TWO EXTREMES...CALLING FOR GRADUAL WEAKENING DUE TO
SHEAR BUT ALLOWING FOR THE REMNANTS OF THE SYSTEM TO LAST FOR 5
DAYS IN AGREEMENT WITH THE UKMET.  IT SHOULD BE NOTED THAT ANY
MOTION NORTH OF THE FORECAST TRACK WOULD BRING GUILLERMO OVER
COOLER WATER AND LET IT DISSIPATE EARLIER THAN CURRENT FORECAST.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/2100Z 16.2N 134.0W    30 KT
 12HR VT     12/0600Z 16.4N 135.7W    25 KT
 24HR VT     12/1800Z 16.7N 138.1W    25 KT...DISSIPATING
 36HR VT     13/0600Z 16.9N 140.4W    20 KT...REMNANT LOW
 48HR VT     13/1800Z 17.2N 142.6W    20 KT...REMNANT LOW
 72HR VT     14/1800Z 18.0N 147.0W    20 KT...REMNANT LOW
 96HR VT     15/1800Z 18.5N 151.0W    20 KT...REMNANT LOW
120HR VT     16/1800Z 18.5N 155.0W    20 KT...REMNANT LOW
 
 
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