ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GREG DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP072011 800 AM PDT FRI AUG 19 2011 GREG HAS SHOWN SIGNS OF WEAKENING OVER COOLER WATERS IN THE PAST SIX HOURS. CLOUD TOPS HAVE WARMED NEAR THE CORE OF THE CYCLONE...WHICH HAS BECOME DETACHED FROM THE CONVECTIVE BAND TO THE SOUTHEAST OF THE CENTER. CURRENT SATELLITE INTENSITY ESTIMATES FROM SAB AND TAFB BOTH CAME IN AT 65 KT...BUT DATA-T NUMBERS WERE BOTH T3.5/55 KT. GIVEN THE STEADY CONVECTIVE EROSION NOTED IN THE SATELLITE PRESENTATION SINCE THE 12Z FIXES...THE INITIAL INTENSITY HAS BEEN SET AT 55 KT. GREG SHOULD RAPIDLY WEAKEN OVER COOLER WATERS IN THE NEXT COUPLE OF DAYS. THE CORE OF THE CYCLONE IS NEARING 25C WATERS...AND SEA SURFACE TEMPERATURES WILL BE DECLINING BELOW 24C BY TOMORROW. THE OFFICIAL FORECAST CALLS FOR GREG TO WEAKEN INTO A DEPRESSION ON SATURDAY AND TO A REMNANT LOW ON SUNDAY...WHICH IS A SLIGHTLY FASTER RATE OF WEAKENING FROM THE PRIOR FORECAST AND LOWER THAN ALL OF THE AVAILABLE INTENSITY GUIDANCE. THE INITIAL MOTION IS 275 DEGREES AT 12 KNOTS. THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE TRACK REASONING...AND GREG IS EXPECTED TO CONTINUE ON A GENERAL WESTERLY MOTION OVER THE NEXT COUPLE OF DAYS UNDER THE STEERING INFLUENCE OF THE NORTHEAST PACIFIC SUBTROPICAL RIDGE. AS THE SYSTEM WEAKENS AND BECOMES INCREASINGLY SHALLOW...A SLIGHT TURN TO THE WEST-SOUTHWEST IS EXPECTED ON SUNDAY. THE TRACK FORECAST IS ROUGHLY DOWN THE MIDDLE OF THE DYNAMICAL AND CONSENSUS GUIDANCE. FORECAST POSITIONS AND MAX WINDS INIT 19/1500Z 19.1N 115.7W 55 KT 65 MPH 12H 20/0000Z 19.3N 117.5W 45 KT 50 MPH 24H 20/1200Z 19.3N 119.6W 35 KT 40 MPH 36H 21/0000Z 19.1N 121.3W 30 KT 35 MPH 48H 21/1200Z 18.8N 122.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 22/1200Z 18.3N 125.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 23/1200Z...DISSIPATED $$ FORECASTER WROE/STEWART NNNN
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