ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM HURRICANE HILARY DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT SUN AUG 21 2005 TWO MICROWAVE PASSES...A TRMM PASS AT 0950Z AND AN AQUA PASS AT 0907Z...SUGGEST THAT HILARY MAY NOT BE QUIRE AS WELL ORGANIZED AS IT WAS OVERNIGHT. THE TRMM PASS IN PARTICULAR SHOWS AN EROSION OF THE BANDING OR EYEWALL-LOOKING FEATURE WITH A CENTER NORTH OF OUR PREVIOUS TRACK. DVORAK CLASSIFICATIONS...WHICH ARE UNCHANGED FROM 6 HOURS AGO...ARE UNCERTAIN DUE TO QUESTIONS ABOUR THE CENTER LOCATION. THE ADVISORY INTENSITY WILL REMAIN 70 KT PENDING VISIBLE IMAGERY...AND HOPEFULLY SOME MORE CLARITY ABOUT THE STRUCTURE OF THE CYCLONE. HILARY IS MAINTAINING VERY COLD CONVECTION AT THIS TIME AND HAS A LARGE ENVELOPE OF MOISTURE. BOTH THE SHIPS AND GFDL GUIDANCE SUGGEST ADDITIONAL STRENGTHENING IS LIKELY BEFORE HILARY REACHES COOLER WATERS IN ABOUT 48 HOURS. THE OFFICIAL FORECAST DIFFERS FROM THE PREVIOUS ADVISORY WITH A FASTER DECAY OVER THE COLD WATER...MORE IN LINE WITH THE GFDL GUIDANCE. THE MICROWAVE PASSES REQUIRE A NORTHWARD ADJUSTMENT IN THE PRIOR TRACK...WITH AN INITIAL MOTION ESTIMATE OF 295/11. HILARY IS SOUTH OF A MINOR WEAKNESS IN THE SUBTROPICAL RIDGE...BUT WILL SHORTLY BYPASS THIS WEAKNESS. MODEL GUIDANCE HAS BEEN TOO FAST WITH THE FORWARD SPEED OF HILARY AND STILL APPEARS TO BE INCONSISTENT WITH THE PRESENT ESTIMATE OF 11 KT. A MORE SIGNIFICANT EROSION OF THE RIDGE IS EXPECTED WITHIN ABOUT 48 HOURS AS A MID-LEVEL TROUGH IS FORECAST TO BECOME ESTABLISHED OVER SOUTHERN CALIFORNIA IN ABOUT 48 HOURS. THIS PATTERN SHOULD ALLOW FOR A TEMPORARY INCREASE IN SPEED OVER THE NEXT 24 HOURS...FOLLOWED BY A SLOWING OF THE MOTION THEREAFTER. THE OFFICIAL FORECAST REMAINS SLOWER THAN MOST OF THE DYNAMICAL GUIDANCE AND IS ALSO SOMEWHAT ON THE RIGHT SIDE OF A FAIRLY NARROW GUIDANCE ENVELOPE. 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 FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 21/1500Z 15.6N 106.1W 70 KT 12HR VT 22/0000Z 16.4N 107.9W 80 KT 24HR VT 22/1200Z 17.3N 110.4W 85 KT 36HR VT 23/0000Z 18.1N 112.5W 90 KT 48HR VT 23/1200Z 18.8N 114.2W 90 KT 72HR VT 24/1200Z 20.0N 116.5W 75 KT 96HR VT 25/1200Z 21.0N 118.5W 55 KT 120HR VT 26/1200Z 22.5N 120.5W 40 KT $$ NNNN
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Page last modified: Sunday, 21-Aug-2005 14:40:13 UTC