Tropical Storm GREG

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TROPICAL STORM GREG DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT SAT AUG 13 2005
 
VISIBLE IMAGERY OF GREG STILL SHOWS A BURST OF CONVECTION IN THE
SOUTHERN QUADRANT AS NORTHERLY SHEAR IMPINGES ON THE SYSTEM. THE
CENTER WAS FULLY EXPOSED...BUT THE CONVECTION CONTINUES TO
INTERMITTENTLY FLARE UP NEAR THE CENTER. DVORAK INTENSITY ESTIMATES
FROM TAFB ARE 2.5 AND FROM SAB ARE 2.0 SO THE SYSTEM IS A
BORDERLINE TROPICAL STORM. A RECENT QUIKSCAT OVERPASS OVER THE
EASTERN PORTION OF THE CYCLONE DOES HAVE 35 KT WINDS...SO THE
INITIAL INTENSITY ESTIMATE IS HELD AT 35 KT FOR THIS ADVISORY. WIND
RADII WERE ALSO ADJUSTED BASED ON THIS SAME QUIKSCAT OVERPASS
INFORMATION.

THE SHORT TERM INTENSITY FORECAST HOLDS GREG AT 35 KT AND SLOWLY
WORKS THE INTENSITY UP TO 60 KT BY 72 HOURS. THIS FORECAST IS VERY
SIMILAR TO THE FSSE AND SHIPS GUIDANCE. ON THE OTHER HAND...THE
GFDL DEPICTS A MORE AGGRESSIVE INTENSITY SCENARIO BY DEVELOPING
GREG TO HURRICANE STRENGTH IN 36 HRS. THE OFFICIAL FORECAST CALLS
FOR SLOW DEVELOPMENT IN THE MEANTIME. BY THE EXTENDED FORECAST
PERIOD... THE OFFICIAL FORECAST DOES BRING GREG TO HURRICANE
STRENGTH BEYOND 96 HRS...THIS IS CONSERVATIVE APPROACH COMPARED TO
THE GFDL.

THE INITIAL MOTION ESTIMATE IS 290/5. MOST OF THE SHORT TERM TRACK
GUIDANCE QUICKLY DIVES GREG SOUTHWESTWARD. THE GFS IS THE SOUTHERN
MOST OUTLIER IN THE GROUP. BEYOND 36 HRS...THE TRACK TURNS WEST AND
REMAINS SO UNTIL THE END OF THE FORECAST PERIOD. THE FORECAST TRACK
REMAINS JUST NORTH OF THE MODEL CONSENSUS CONU...GUNS AND GUNA. THE
LARGE SPREAD IN THE MODELS EARLY IN THE FORECAST YIELD A BIT OF
UNCERTAINTY BUT A GENERAL LONG TERM WEST MOTION IS ANTICIPATED.
 
FORECASTER SISKO/AVILA
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/2100Z 15.5N 114.9W    35 KT
 12HR VT     14/0600Z 15.3N 115.6W    35 KT
 24HR VT     14/1800Z 14.7N 116.4W    35 KT
 36HR VT     15/0600Z 14.0N 117.5W    40 KT
 48HR VT     15/1800Z 14.0N 119.0W    45 KT
 72HR VT     16/1800Z 14.0N 122.5W    55 KT
 96HR VT     17/1800Z 14.5N 125.0W    65 KT
120HR VT     18/1800Z 15.5N 127.5W    65 KT
 
 
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