ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM HURRICANE HILARY DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT SUN AUG 21 2005 THE ORGANIZATION OF THE HURRICANE IS SLOWLY INCREASING...WITH A VERY COLD CDO ON CONVENTIONAL IR IMAGES AND BANDING FEATURES EVIDENT ON MICROWAVE IMAGERY. INTENSITY ESTIMATES...USING THE EMBEDDED CENTER PATTERN WITH THE DVORAK TECHNIQUE...WERE 77 AND 65 KT FROM SAB AND TAFB RESPECTIVELY. CURRENT INTENSITY IS SET AT 70 KT. HILARY HAS STRONG UPPER-LEVEL OUTFLOW TO THE SOUTH AND WEST...WHICH IS INDICATIVE OF SOME NORTHEASTERLY SHEAR. GLOBAL MODEL UPPER-LEVEL WIND FORECASTS INDICATE THAT THIS SHEAR WILL DIMINISH OVER THE NEXT COUPLE OF DAYS. SOME OF THE PARAMETERS SHOWN TO BE IMPORTANT IN THE STATISTICAL SCHEME FOR FORECASTING SIGNIFICANT INTENSIFICATION...SUCH AS AN ABUNDANCE OF COLD CLOUD TOPS AND HIGH RELATIVE HUMIDITY IN THE LOW- TO MID-TROPOSPHERE... ARE PRESENT. CURIOUSLY... HOWEVER...THE LATEST SHIPS MODEL RUN HAS BACKED OFF A LITTLE ON ITS INTENSITY FORECAST. THE OFFICIAL WIND SPEED FORECAST FOR THIS ADVISORY IS SIMILAR TO THE PREVIOUS ONE. MICROWAVE FIXES FROM SSM/I...AMSU...AND WINDSAT...HAVE BEEN HELPFUL IN LOCATING THE CENTER. USING THESE FIXES...THE INITIAL MOTION ESTIMATE...280/11...IS A LITTLE SLOWER THAN BEFORE. A MID-LEVEL RIDGE TO THE NORTH OF THE HURRICANE IS FORECAST TO WEAKEN IN ABOUT 48 HOURS IN RESPONSE TO A TROUGH THAT DROPS INTO CALIFORNIA. IN RESPONSE TO THESE CHANGES IN THE STEERING CURRENT...HILARY IS FORECAST TO TURN TOWARD THE NORTHWEST AND SLOW LATER IN THE FORECAST PERIOD. HOWEVER...THE LATEST DYNAMICAL MODEL CONSENSUS HAS SHIFTED A LITTLE TO THE LEFT AT 4-5 DAYS IN COMPARISON TO THE PREVIOUS PACKAGE. THE OFFICIAL TRACK FORECAST IS A LITTLE SLOWER THAN IN THE PREVIOUS ADVISORY AND IS QUITE CLOSE TO THE FSU SUPERENSEMBLE TRACK. RAINBANDS PRODUCING OCCASIONAL GUSTY WINDS AND LOCALLY HEAVY RAINFALL ARE AFFECTING PORTIONS OF THE SOUTHWESTERN COAST OF MEXICO WEST OF ACAPULCO. CONDITIONS THERE SHOULD GRADUALLY IMPROVE AS HILARY MOVES AWAY FROM THE COAST DURING THE NEXT DAY OR SO. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 21/0900Z 14.6N 105.3W 70 KT 12HR VT 21/1800Z 15.2N 107.4W 80 KT 24HR VT 22/0600Z 15.9N 109.9W 85 KT 36HR VT 22/1800Z 16.7N 112.3W 90 KT 48HR VT 23/0600Z 17.5N 114.3W 90 KT 72HR VT 24/0600Z 19.0N 117.0W 80 KT 96HR VT 25/0600Z 20.5N 118.5W 70 KT 120HR VT 26/0600Z 22.0N 120.0W 55 KT $$ NNNN
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Page last modified: Sunday, 21-Aug-2005 08:40:13 UTC