060 WDPN31 PGTW 251500 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (RUSA) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 251200Z0 TO 281200Z3 AUG 02. A. TYPHOON (TY) 21W (RUSA), LOCATED APPROXIMATELY 500 NM EAST-SOUTHEAST OF IWO JIMA, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS DURING THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 251130Z2 INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 77 KNOTS AND MICROWAVE IMAGERY THAT INDICATES INCREASING COVERAGE AND A SMALL EYE FEATURE. ANIMATED WATER VAPOR IMAGERY INDICATES THAT THE UPPER LEVEL LOW TO THE EAST IS ENHANCING OUTFLOW. B. THE MID-LEVEL SUBTROPICAL RIDGE NORTH OF THE SYSTEM IS EXPECTED TO BUILD WESTWARD. TY 21W IS FORECAST TO TRACK WEST- NORTHWESTWARD IN THE EASTERLY FLOW. THE AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, UKMET OFFICE (EGRR), NCEP AVIATION (AVN), COAMPS, AFWA MM5, AND THE JAPANESE GLOBAL (JGSM) AND TYPHOON (JTYM) MODELS ARE IN EXCELLENT AGREEMENT. THE DYNAMIC MODELS HAVE BEEN SHIFTING THE FORECAST SOLUTION MORE WESTWARD IN RESPONSE TO A DEEPENING LONG WAVE TROF UPSTREAM AND BUILDING RIDGE ALONG THE FORECAST TRACK. OUR FORECAST IS BASED ON A BLEND OF ALL AVAILABLE DYNAMIC AIDS AND PERSISTENCE. C. AN UPPER LEVEL LOW TO THE EAST OF THE SYSTEM IS ENHANCING OUTFLOW ON THE POLEWARD SIDE. TY 21W IS EXPECTED INTENSIFY AT OR JUST BELOW A CLIMATOLOGICAL RATE THROUGH THE MID PERIOD. AND SLOW DEVELOPMENT IS FORECAST FOR THE REMAINDER OF THE FORECAST PERIOD. D. WIND RADII ANALYSIS IS BASED ON MICROWAVE IMAGERY AND A RECENT QUIKSCAT PASS. FORECAST WIND RADII IN THE LATE PERIOD ARE BASED ON CLIMATOLOGY FOR AN AVERAGE-SIZED SYSTEM. FORECAST TEAM: SMITH/DANIEL/ROSSE/CUTMAN/SCHAEFER/COOK//