ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM 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 NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:56 UTC