Tropical Storm GUILLERMO

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TROPICAL DEPRESSION GUILLERMO DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT MON AUG 11 2003
 
GUILLERMO REMAINS IN AN ENVIRONMENT OF LIGHT/MODERATE WESTERLY
SHEAR...AND IS CURRENTLY UNDERGOING A CONVECTIVE BURST NEAR AND TO
THE NORTH OF THE CENTER.  SATELLITE INTENSITY ESTIMATES ARE 30 KT
FROM TAFB AND AFWA...AND 25 KT FROM SAB.  THE INITIAL INTENSITY
REMAINS 30 KT FOR THIS ADVISORY.

THE INITIAL MOTION IS 275/13.  THE CYCLONE IS CURRENTLY ON THE SOUTH
SIDE OF A STRONG SUBTROPICAL RIDGE.  LARGE-SCALE MODELS FORECAST
THIS 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 SOUTH TO BE PICKED UP BY THE
TROUGH...SO THE MOST LIKELY SCENARIO IS A 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 ENVELOPE IN BEST AGREEMENT WITH THE
UKMET.

THE FORECAST TRACK KEEPS GUILLERMO OVER ROUGHLY 26C SEA SURFACE
TEMPERATURES...SO THE INTENSITY FORECAST IS DEPENDENT MAINLY ON THE
VERTICAL SHEAR.  THE GFS AND CANADIAN FORECAST STRONG UPPER-LEVEL
WESTERLIES ALONG THE PATH OF THE CYCLONE...WHILE THE UKMET AND THE
NOGAPS HAVE A SOMEWHAT MORE FAVORABLE ENVIRONMENT. THE INTENSITY
FORECAST WILL SOMEWHAT COMPROMISE BETWEEN THESE TWO EXTREMES...
CALLING FOR WEAKENING DUE TO SHEAR BUT ALLOWING FOR AT LEAST THE
REMNANTS OF THE SYSTEM TO LAST FOR 5 DAYS IN AGREEMENT WITH THE
UKMET AND NOGAPS.

FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1500Z 16.0N 132.6W    30 KT
 12HR VT     12/0000Z 16.1N 134.3W    30 KT
 24HR VT     12/1200Z 16.3N 136.8W    25 KT...DISSIPATING
 36HR VT     13/0000Z 16.5N 138.9W    20 KT...REMNANT LOW
 48HR VT     13/1200Z 16.8N 141.2W    20 KT...REMNANT LOW
 72HR VT     14/1200Z 17.5N 145.5W    20 KT...REMNANT LOW
 96HR VT     15/1200Z 18.0N 149.5W    20 KT...REMNANT LOW
120HR VT     16/1200Z 18.5N 153.5W    20 KT...REMNANT LOW
 
 
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