Tropical Storm GREG

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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
 
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