WDPN31 PGTW 260300 UNCLAS //N03145// MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM (TS) 27W/ WARNING NR 08// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 260000Z8 TO 290000Z1 DEC 2003. A. TROPICAL STORM (TS) 27W, LOCATED APPROXIMATELY 445 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWARD AT 05 KNOTS OVER THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 252330Z5 VISIBLE SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON CURRENT SATELLITE INTENSITY ESTIMATES OF 30 AND 35 KNOTS. B. TS 27W IS EXPECTED TO CONTINUE TO MOVE WEST-SOUTHWESTWARD UNDER THE STEERING INFLUENCE OF THE NORTHEAST MONSOON. A SECOND SURGE IN THE NORTHEAST MONSOON WILL INTERACT WITH TS 27W AFTER 24 HOURS RESULTING IN A WEST-SOUTHWESTWARD MOVEMENT OUT TO 72 HOURS. ALL THE AVAILABLE DYNAMIC AIDS INCLUDING NOGAPS (NGPS), UK-MET OFFICE MODEL (EGRR), THE NCEP GFS (JAVN), GFDN, COAMPS, JMA GLOBAL SPECTRAL MODEL (JGSM) AND THE JMA JTYM MODEL ARE IN GOOD AGREEMENT WITH THIS SCENARIO. THIS FORECAST IS BASED ON A ALL THE DYNAMIC AIDS. C. TS 27W MAY INTENSIFY SLIGHTLY IN THE NEXT 12 TO 24 HOURS UNTIL AN UPPER LEVEL RIDGE MOVES OVER LUZON AND BRINGS CONVERGENT FLOW AND INCREASING VERTICAL SHEAR. HOWEVER, INTERACTION WITH THE NORTHEAST MONSOON, WITH DRY, COOL AIR IS EXPECTED TO WEAKEN AND AIDE IN THE DISSIPATION OF THE SYSTEM AT THE 72 HOUR POINT. D. FORECAST WIND RADII FORECAST ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED SYSTEM. 3. FORECAST TEAM: LEEJOICE/MENEBROKER/COOK// NNNN