WDPN32 PGTW 131500 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (PHANFONE) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 131200Z7 AUG TO 161200Z0 AUG 02. A. TYPHOON (TY) 19W (PHANFONE), LOCATED APPROXIMATELY 625 NM EAST-NORTHEAST OF GUAM, HAS TRACKED NORTHWESTWARD AT 17 KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 131130Z9 ENHANCED INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 55, 65 AND 77 KNOTS. A 131058Z8 SSM/I PASS DEPICTS A BANDING EYE FEATURE AND DEEP CONVECTION IN THE NORTHERN SEMI-CIRCLE WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER. B. A MID TO HIGH-LEVEL SUBTROPICAL RIDGE NORTH OF TY 19W IS EXPECTED TO BUILD THROUGH THE FORECAST PERIOD AND SHIFT TO A ZONAL ORIENTATION. A MID-LATITUDE LOW IS EXPECTED TO DEVELOP OVER THE NORTHERN PORTION OF THE SEA OF JAPAN BY THE END OF THE PERIOD, WEAKENING THE SUBTROPICAL RIDGE. TY 19W IS FORECAST TO TRACK NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE THROUGH 48 HOURS, AND THEN NORTH-NORTHWESTWARD AS THE RIDGE BEGINS TO WEAKEN. THE AVAILABLE DYNAMIC AIDS CONSIST OF NCEP AVIATION (AVN), GFDN, NOGAPS, UKMET GLOBAL (EGRR), AFWA, COAMPS, AND THE JAPANESE GLOBAL (JGSM) AND TYPHOON (JTYM) MODELS. ALL AIDS ARE IN GOOD AGREEMENT WITH THIS SCENARIO WITH THE EXCEPTION OF AVN. AVN WEAKENS TY 19W AND THEN MERGES IT WITH A DEVELOPING TROPICAL STORM TO THE WEST. BASED ON THE INTENSIFICATION OF THE SYSTEM, SATELLITE IMAGERY, AND SYNOPTIC DATA, THIS SCENARIO IS UNLIKELY. OUR FORECAST IS BASED ON A BLEND ALL AVAILABLE DYNAMIC AIDS WITH LESS EMPHASIS ON AVN. C. AN UPPER LEVEL LOW NORTH-NORTHWEST OF THE SYSTEM IS EXPECTED TO SLOWLY PROPAGATE WESTWARD AND FILL. THIS FILLING LOW AND A SHORTWAVE TROUGH EAST OF THE SYSTEM WILL CONTINUE TO PROVIDE FAVORABLE OUTFLOW CONDITIONS OVER THE NEXT 24 HOURS. THE NEAR EQUATORIAL RIDGE SOUTH OF THE SYSTEM IS EXPECTED TO CONTINUE TO PROVIDE CROSS-EQUATORIAL OUTFLOW THROUGH THE PERIOD. TY 19W IS EXPECTED TO INTENSIFY AT A CLIMATOLOGICAL THROUGHOUT THE FORECAST PERIOD. D. CURRENT WIND RADII ARE BASED ON A RECENT QUIKSCAT PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE SYSTEM. FORECAST TEAM: WINGEART/LAM/KUMAGA/STATEN// NNNN