Tropical Storm GREG

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TROPICAL STORM GREG DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT AUG 13 2005
 
INFRARED AND SHORTWAVE IR IMAGERY OF GREG SHOW AN INTERMITTENTLY
EXPOSED CENTER AND FLARE UPS OF CONVECTION IN THE SOUTHERN
QUADRANT. NORTHERLY SHEAR IS STILL IMPINGING ON THE SYSTEM AND GREG
CONTINUES TO STRUGGLE IN ITS CURRENT ENVIRONMENT. DVORAK INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 2.5 RESPECTIVELY GIVING AN
INTENSITY ESTIMATE OF 35 KT... WHILE AFWA ESTIMATES ARE SLIGHTLY
LOWER. THE INTENSITY FOR GREG REMAINS AT 35 KT.

THE INTENSITY FORECAST DOES DEVIATE SLIGHTLY FROM THE PREVIOUS. THE
SHORT TERM TREND HOLDS GREG AT 35 KT AND SLOWLY WORKS THE INTENSITY
UP TO 60 KT BY 72 HOURS WHICH IS SIMILAR TO SHIPS. HOWEVER...
BEYOND 72 HOURS SHIPS KEEPS GREG AT TROPICAL STORM STRENGTH
WHILE THE GFDL INCREASES GREG TO A HURRICANE AT 48 HOURS. THE
OFFICIAL INTENSITY FORECAST TAKES A CONSERVATIVE APPROACH BY
KEEPING GREG AS A TROPICAL STORM IN THE MIDDLE OF THE FORECAST
PERIOD AND NUDGING IT TO HURRICANE STATUS IN THE EXTENDED PERIODS.
THIS FORECAST MOSTLY FOLLOWS SHIPS... HOWEVER IT DOES TAKE INTO
ACCOUNT THE GFDL SOLUTION LATER ON IN THE PERIOD.

THE INITIAL MOTION ESTIMATE IS 315/3. GIVEN THAT THE CENTER IS
PARTIALLY EXPOSED...THE SHORT TERM MOTION WILL CONTINUE A SLOW
MOVEMENT IN THE NORTHWESTWARD DIRECTION... AND IS CONSISTENT WITH
THE SHALLOW BETA ADVECTION MODEL. THE DYNAMICAL MODEL SUITE QUICKLY
MOVES GREG TO THE SOUTHWEST IN THE SHORT TERM WHICH GIVEN ITS
PRESENT MOTION MAY BE UNLIKELY. CONSEQUENTLY... THE OFFICIAL TRACK
LEANS MORE TOWARD THE BAMS AND SLOWLY TRENDS BACK TOWARD THE MODEL
CONSENSUS LATER ON IN THE FORECAST. 
 
FORECASTER SISKO/AVILA
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/1500Z 15.4N 114.3W    35 KT
 12HR VT     14/0000Z 15.6N 114.8W    35 KT
 24HR VT     14/1200Z 15.4N 115.7W    40 KT
 36HR VT     15/0000Z 15.0N 116.5W    45 KT
 48HR VT     15/1200Z 15.0N 118.0W    50 KT
 72HR VT     16/1200Z 15.0N 120.5W    60 KT
 96HR VT     17/1200Z 15.0N 123.5W    65 KT
120HR VT     18/1200Z 15.5N 126.0W    65 KT
 
 
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