ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM GREG DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP072011 200 AM PDT SAT AUG 20 2011 AFTER A SMALL BURST OF MODERATE TO DEEP CONVECTION AROUND 00Z... CONVECTION HAS DWINDLED SOMEWHAT BOTH IN VERTICAL DEPTH AND AREAL COVERAGE SINCE THEN. A BRIEF EYE-LIKE FEATURE HAS ALSO BEEN REVEALED AS THE CIRRUS CANOPY HAS THINNED. SATELLITE INTENSITY ESTIMATES ARE 45 KT AND 35 KT FROM TAFB AND SAB...RESPECTIVELY...SO THE INITIAL INTENSITY IS LOWERED TO 40 KT FOR THIS ADVISORY. THE INITIAL MOTION IS 275/09. GREG REMAINS ON TRACK SO THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST RATIONALE. A GRADUAL TURN TOWARD THE WEST-SOUTHWEST IS FORECAST AS GREG CONTINUES TO WEAKEN OVER PROGRESSIVELY COOLER WATER...BECOMING A SHALLOW SYSTEM AND BEING STEERED BY THE LARGE LOW-LEVEL CENTRAL PACIFIC HIGH PRESSURE RIDGE TO THE NORTH OF THE CYCLONE. THE GLOBAL MODELS ARE IN EXCELLENT AGREEMENT ON THIS SCENARIO...AND THE FORECAST TRACK IS JUST AN EXTENSION OF THE PREVIOUS ADVISORY TRACK. GREG IS CURRENTLY OVER 23.5C SSTS...AND ONLY COOLER WATER AND DRY STABLE AIR LIE AHEAD OF THE CYCLONE. AS A RESULT OF THESE UNFAVORABLE THERMODYNAMIC CONDITIONS...GREG SHOULD CONTINUE TO STEADILY WEAKEN AND GRADUALLY SPIN DOWN INTO A NON-CONVECTIVE REMNANT LOW PRESSURE SYSTEM BY 24 HOURS OR SO...AND DISSIPATE BY 96 HOURS...IF NOT SOONER. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 19.7N 119.0W 40 KT 45 MPH 12H 20/1800Z 19.8N 120.4W 30 KT 35 MPH 24H 21/0600Z 19.7N 122.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 21/1800Z 19.6N 123.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 22/0600Z 19.2N 125.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 23/0600Z 18.2N 127.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 24/0600Z...DISSIPATED $$ FORECASTER STEWART NNNN
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