Tropical Storm GUILLERMO

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TROPICAL STORM GUILLERMO DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102009
200 AM PDT THU AUG 13 2009
 
GUILLERMO HAS CONTINUED TO BECOME BETTER ORGANIZED WITH MICROWAVE
AND SATELLITE IMAGERY REVEALING A BAND OF DEEP CONVECTION THAT
WRAPS MORE THAN HALF WAY AROUND THE CENTER.  SATELLITE INTENSITY
ESTIMATES FROM TAFB AND SAB ARE T3.0...WHICH SUPPORTS RAISING THE
INITIAL INTENSITY TO 45 KT.  GUILLERMO IS EXPECTED TO REMAIN IN A
LOW SHEAR ENVIRONMENT...CONDUCIVE FOR STRENGTHENING...DURING THE
NEXT COUPLE OF DAYS.  HOWEVER...DURING THAT TIME THE CYCLONE WILL
BE MOVING OVER GRADUALLY COOLER WATER.  THE SHIPS...LGEM...AND HWRF
INTENSITY GUIDANCE FORECAST A PEAK INTENSITY IN 24 TO 36 HOURS OF
AROUND 65 KT...WHILE THE GFDL SHOWS ONLY A LITTLE ADDITIONAL
STRENGTHENING.  THE OFFICIAL FORECAST IS BETWEEN THESE
SOLUTIONS...IN BEST AGREEMENT WITH INTENSITY CONSENSUS.  EVEN
THOUGH THE OFFICIAL FORECAST KEEPS GUILLERMO JUST BELOW HURRICANE
STRENGTH...THE MAXIMUM WIND SPEED PROBABILITY TABLE SHOWS THAT
GUILLERMO HAS ABOUT A 35 PERCENT CHANCE OF BEING A HURRICANE AT THE
36 OR 48 HOUR FORECAST TIMES.
 
THE FORWARD MOTION OF THE TROPICAL STORM REMAINS UNCHANGED AT
290/14. GUILLERMO IS FORECAST TO REMAIN SOUTH OF A MID- TO
UPPER-LEVEL RIDGE THAT EXTENDS FROM NORTHERN MEXICO WESTWARD INTO
THE EASTERN PACIFIC.  THE RIDGE IS FORECAST TO STRENGTHEN AND 
BUILD WESTWARD DURING THE NEXT FEW DAYS...WHICH IS EXPECTED TO 
TURN THE CYCLONE MORE WESTWARD.  THE TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH 72 HOURS...WITH A LITTLE MORE SPREAD THEREAFTER. 
THE OFFICIAL FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE
AND THE PREVIOUS NHC TRACK THROUGH 72 HOURS. THEREAFTER...THE NEW
FORECAST HAS BEEN ADJUSTED A LITTLE NORTH OF THE PREVIOUS TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/0900Z 16.9N 120.5W    45 KT
 12HR VT     13/1800Z 17.2N 122.6W    50 KT
 24HR VT     14/0600Z 17.6N 125.2W    55 KT
 36HR VT     14/1800Z 18.0N 127.9W    60 KT
 48HR VT     15/0600Z 18.4N 130.5W    60 KT
 72HR VT     16/0600Z 19.1N 135.8W    50 KT
 96HR VT     17/0600Z 19.5N 141.5W    45 KT
120HR VT     18/0600Z 19.5N 147.5W    35 KT
 
$$
FORECASTER BROWN
 
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