ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM RTD 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 NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:57 UTC