Tropical Storm GUILLERMO

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TROPICAL STORM GUILLERMO DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT AUG 09 2003
 
THE OVERALL CONVECTIVE CLOUD PATTERN AND CLOUD TOPS HAVE WAXED AND
WANED OVERNIGHT WITH A BRIEF BURST OF CONVECTION HAVING OCCURRED
BETWEEN 09-12Z. SINCE THEN...TOPS HAVE WARMED AND THE LOW-LEVEL
CENTER IS ESTIMATED TO BE NORTHEAST OF THE HIGHEST CLOUD TOPS. THE
INITIAL INTENSITY IS MAINTAINED AT 50 KT BASED ON A BLEND OF DVORAK
SATELLITE INTENSITY ESTIMATES OF 55 KT AND 45 KT FROM TAFB AND
SAB...RESPECTIVELY. UPPER-LEVEL OUTFLOW IS FAIRLY SYMMETRICAL AND
EXPANDING SLIGHTLY IN ALL QUADRANTS...EXCEPT TO THE EAST.
 
THE INITIAL MOTION ESTIMATE IS 265/12. THE INITIAL POSITION WAS
ADJUSTED A LITTLE SOUTH OF THE PREVIOUS ADVISORY POSITION BASED ON
AN EARLIER TRMM OVERPASS WHICH SHOWED THE LOW-LEVEL CENTER
DISPLACED A LITTLE SOUTH OF THE MID-LEVEL CIRCULATION. THE FORECAST
TRACK WAS ADJUSTED SOUTH OF THE PREVIOUS TRACK DUE TO EXPECTED
BINARY INTERACTION WITH LARGE AND STRENGTHENING TROPICAL DEPRESSION
EIGHT-E LOCATED ABOUT 575 NMI TO THE EAST. TD-8E IS MOVING ABOUT
3-4 KT FASTER THAN GUILLERMO...SO SOME BINARY INTERACTION IS
EXPECTED TO RESUME SHORTLY..IF NOT ALREADY. THE STRONG SUBTROPICAL
RIDGE TO THE NORTH WILL MOVE GUILLERMO WESTWARD WHILE TD-8E IS
EXPECTED TO IMPART A WEAK SOUTHWARD COMPONENT OF MOTION. THE RESULT
IS THAT GUILLERMO IS FORECAST TO MOVE SLIGHTLY SOUTH OF DUE WEST
THROUGH 72 HOURS AND THEN TURN WESTWARD AFTER THAT. THIS IS
CONSISTENT WITH THE GFDL...GFS...AND GFS ENSEMBLE MEAN FORECASTS.
WHILE THE OFFICIAL FORECAST TRACK IS ALONG THE SOUTHERN EDGE OF THE
GUIDANCE ENVELOPE...IT IS NOT AS FAR SOUTH AS THE GFS MODEL.

THE OUTFLOW ON THE WEST SIDE OF TD-8E APPEARS TO BE UNDERCUTTING 
THE OUTFLOW FROM GUILLERMO IN THE EASTERN SEMICIRCLE. THIS MAY BE
PARTLY RESPONSIBLE FOR THE RECENT WARMING OF THE CENTRAL
CONVECTION. THE SHIPS MODEL FORECASTS THE 200 MB SHEAR TO REMAIN
LESS THAN 10 KT THROUGHOUT THE PERIOD AND EVEN BRINGS GUILLERMO TO
65 KT IN 72 HOURS...AND REMAIN AT THAT STRENGTH THROUGH 120 HOURS.
HOWEVER...SINCE TD-8E IS FORECAST TO STRENGTHEN AND MOVE CLOSER TO
GUILLERMO...THE SHEAR IN THE 300 MB LAYER THAT IS PRESENTLY
UNDERCUTTING THE 200 MB OUTFLOW WILL LIKELY INCREASE SOME MORE. FOR
THIS REASON...THE PREVIOUS INTENSITY FORECAST HAS BEEN MAINTAINED
...EVEN THOUGH THE CYCLONE WILL BE LOSING LATITUDE AND MOVING OVER
SLIGHTLY WARMER WATER.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/1500Z 15.7N 122.8W    50 KT
 12HR VT     10/0000Z 15.6N 124.6W    50 KT
 24HR VT     10/1200Z 15.4N 127.1W    55 KT
 36HR VT     11/0000Z 15.2N 129.6W    60 KT
 48HR VT     11/1200Z 15.0N 132.1W    60 KT
 72HR VT     12/1200Z 15.0N 135.5W    50 KT
 96HR VT     13/1200Z 15.0N 140.5W    40 KT
120HR VT     14/1200Z 15.0N 145.5W    35 KT
 
 
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