WDPN32 PGTW 191500 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W WARNING NR 12// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 191200Z3 TO 241200Z9 JUL 2003. A. TYPHOON (TY) 09W (IMBUDO), LOCATED APPROXIMATELY 260 NM WEST-NORTHWEST OF YAP ISLAND, HAS TRACKED WESTWARD AT 07 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON 191130Z5 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 77 AND 90 KNOTS. A 191053Z9 TRMM PASS INDICATED A ROUND, SYMETRIC 16 NM EYE IN THE 37 GHZ CHANNEL. B. TY 09W (IMBUDO) IS FORECAST TO CONTINUE TRACKING WESTWARD UNDERNEATH THE MID-LEVEL SUBTROPICAL RIDGE OVER THE NEXT 12 HOURS. AFTERWARDS THE SYSTEM SHOULD TRACK WEST-NORTHWESTWARD AS THE MID- LEVEL RIDGE BEGINS TO WEAKEN DUE TO A COLD AIR SURGE FROM A PASSING BAROCLINIC LOW OVER JAPAN AND A BUILDING HIGH OVER NORTHEAST CHINA. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, GFS, COAMPS, JGSM, JTYM, GFDN, EGRR, AND MM5 ARE IN GOOD AGREEMENT WITH THIS SCENARIO. THIS FORECAST IS BASED ON ALL THE DYNAMIC AIDS WITH LESS EMPHASIS ON THE MM5 WHICH IS SLOW AND POLEWARD OF THE OTHER AIDS. C. OUTFLOW HAS WEAKENEND AS THE SYSTEM TRANSVERSES BENEATH THE SUBTROPICAL RIDGE AND INTENSIFICATION HAS SLOWED. THE UPPER LEVEL RIDGE IS EXPECTED TO MOVE EASTWARD FROM EASTERN CHINA ENHANCING THE NORTHEASTLIES RESULTING IN INCREASING VERTICAL SHEAR. THEREFORE, THE SYSTEM IS EXPECTED TO INTENSIFY JUST BELOW A CLIMATOLOGICAL RATE OVER THE FORECAST PERIOD. D. CURRENT WIND RADII BASED ON A 190926Z7 QUIKSCAT PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN LARGED-SIZED SYSTEM. E. THE LONG RANGE FORECAST TRACK IS BASED ON A BLEND OF THE AVAILABLE MODEL GUIDANCE AND FAVORS A NORTHWESTWARD TRACK THROUGH THE LUZON STRAIGHT TOWARDS SOUTHEAST CHINA. TY 09W IS EXPECTED TO WEAKEN WITH INTERACTION WITH LUZON AND UPPER LEVEL NORTHEASTERLIES. FORECAST TEAM: LEEJOICE/LAM/ANDERSON/ALLEN// NNNN