WDPN31 PGTW 251500 
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 251200Z0 SEP 02 TO 281200Z3 SEP 02.
   A. TROPICAL STORM (TS) 24W (MEKKHALA), LOCATED JUST OF THE 
SOUTHWESTERN COAST OF HAINAN ISLAND, HAS TRACKED NORTHWESTWARD AT 06 
KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 
251130Z3 ENHANCED INFRARED SATELLITE IMAGERY AND SYNOPTIC DATA. THE 
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES 
OF 45, 55 AND 65 KNOTS. ANIMATED INFRARED IMAGERY INDICATES 
IMPROVED BANDING FEATURES OVER THE LAST 6 HOURS.  
   B. A MID-LEVEL SUBTROPICAL RIDGE OVER THE PHILIPPINES IS EXPECTED 
TO CONTINUE TO BUILD WESTWARD INTO THE SOUTH CHINA SEA. A DEVELOPING 
LONGWAVE TROUGH OVER CENTRAL CHINA IS EXPECTED TO DEEPEN AND 
PROPAGATE EASTWARD AFTER 36 HOURS, CAUSING THE SUBTROPICAL RIDGE TO 
REORIENTATE SOUTHWEST-NORTHEAST BY 60 HOURS. TS 24W IS EXPECTED TO 
TRACK NORTH-NORTHWESTWARD THROUGH 24 TO 36 HOURS AND THEN 
NORTHEASTWARD BY 60 HOURS ALONG THE SUBTROPICAL RIDGE. THE 
AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, GFDN, NCEP AVIATION 
(AVN), COAMPS, AND AFWA MM5, UKMET OFFICE, AND THE JAPANESE REGIONAL  
(JTYM) MODELS ARE IN FAIR AGREEMENT. OUR FORECAST IS BASED ON A 
BLEND OF ALL AVAILABLE DYNAMIC AIDS. 
   C. TS 24W IS EXPECTED TO MAINTAIN INTENSITY OVER THE NEXT 12 
HOURS AND THEN WEAKEN SLOWLY AS IT ENGAGES LAND AND ENCOUNTERS 
INCREASING VERTICAL WIND SHEAR.
   D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR 
AN AVERAGE-SIZED SYSTEM.    
FORECAST TEAM: LEEJOICE/HEATH/DUKES/MCCOPPIN//

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