Tropical Storm GREG

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TROPICAL STORM GREG DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT FRI AUG 12 2005
 
THE BURST OF DEEP CONVECTION SEEN EARLIER HAS DIMINISHED...AND AN
AMSU MICROWAVE OVERPASS AT 0537Z SHOWS THE LOW-LEVEL CENTER OF GREG
IS EXPOSED TO THE NORTH OF THE REMAINS OF THE BURST.  SATELLITE
INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND SAB...AND 30 KT FROM
AFWA.  THE INITIAL INTENSITY REMAINS 45 KT.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 275/8...UNCERTAIN BECAUSE
THE AMSU IMAGERY SUGGESTS THE CENTER MAY BE A LITTLE NORTH OF THE
ADVISORY POSITION.  SO FAR...THE TRACK OF GREG IS NOT BEING
AFFECTED BY ITS PROXIMITY TO HURRICANE FERNANDA...AS THERE SEEMS TO
BE ENOUGH RIDGING BETWEEN THE TWO STORMS TO ALLOW GREG TO STAY ON A
WESTERLY TRACK.  THE DYNAMICAL MODEL GUIDANCE HAS COME INTO BETTER
AGREEMENT ON A GENERAL WESTELY MOTION THROUGH THE FORECAST
PERIOD...ALTHOUGH THERE IS STILL A NOTABLE SPREAD BETWEEN THE MORE
NORTHERLY NOGAPS AND THE MORE SOUTHERLY GFS.  THE FORECAST TRACK IS
AN UPDATE OF THE PREVIOUS PACAKAGE...AND IS IN BEST AGREEMENT WITH
THE GFDL...GUNS...AND CONU.

SOME NORTH-NORTHEASTERLY VERTICAL SHEAR HAS DEVELOPED OVER GREG...
WHICH FOR THE MOMENT HAS DISRUPTED THE CONVECTIVE STRUCTURE.  THIS
SHEAR SHOULD DIMINISH WITH TIME AND ALLOW STRENGTHENING.  THE
INTENSITY FORECAST IS BASED ON THE PREMISE THAT THE CONVECTION WILL
RE-ORGANIZE AROUND THE CENTER...WITH GREG REACHING HURRICANE
STRENGTH IN 24-48 HR.  BY THE END OF THE FORECAST PERIOD...GREG
SHOULD BE MOVING OVER GRADUALLY COOLING SEA SURFACE TEMPERATURES...
WHICH SHOULD CAUSE GRADUAL WEAKENING.  THE INTENSITY FORECAST IS A
COMPROMISE BETWEEN THE WEAKER SHIPS AND THE STRONGER GFDL.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/0900Z 13.7N 112.6W    45 KT
 12HR VT     12/1800Z 13.8N 113.6W    55 KT
 24HR VT     13/0600Z 14.0N 114.7W    65 KT
 36HR VT     13/1800Z 14.2N 115.6W    70 KT
 48HR VT     14/0600Z 14.3N 116.5W    75 KT
 72HR VT     15/0600Z 14.5N 118.0W    70 KT
 96HR VT     16/0600Z 14.5N 120.5W    65 KT
120HR VT     17/0600Z 15.0N 124.0W    65 KT
 
 
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