WDPN33 PGTW 300300 MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 19W WARNING NR 18// RMKS/ 1. FOR METEOROLOGISTS. 2. PROGNOSTIC REASONING FOR 300000Z SEP TO 040000Z OCT 2005. SUPER TYPHOON (STY) 19W (LONGWANG), LOCATED APPROXIMATELY 350 NM SOUTHEAST OF OKINAWA, HAS TRACKED WEST-SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY INDICATES THE EYE HAS BECOME RAGGED HOWEVER, A 300012Z SSMI IMAGE INDICATES STY 19W IS UNDERGOING EYE-WALL REPLACEMENT. A 292104Z QUIKSCAT PASS INDICATES THE RADIUS OF THE 35 KNOT WIND FIELD IS LARGER THAN PREVIOUSLY FORECAST. B. STY 19W IS TRACKING WESTWARD UNDER THE STEERING INFLUNCE OF THE RIDGE TO THE NORTHWEST CENTERED OVER EASTERN CHINA AND THE EAST CHINA SEA. THE RIDGE HAS CONTINUED TO BUILD EASTWARD BEHIND THE TROUGH PROPAGATING EASTWARD OFF JAPAN. A WESTWARD TO WEST- NORTHWESTWARD MOTION IS FORECAST TO CONTINUE THROUGH THE FORECAST PERIOD AS THE SYSTEM CONTINUES TO TRACK ALONG THE EQUATORWARD PERIPHERY OF THE STEERING RIDGE. THE DYNAMIC AIDS CONSISTING OF NOGAPS, GFDN, NCEP GFS, JGSM, JTYM, EGRR, WBAR, TCLAPS, AFWA MM5 AND COAMPS ARE IN GOOD AGREEMENT WITH THIS SCENARIO WITH THE EXCEPTION OF AFWA MM5 WHICH IS AN EQUATORWARD OUTLIER. THIS FORECAST IS BASED UPON A CONSENSUS OF AVAILABLE AIDS WITH LESS EMPHASIS ON AFWA MM5. C. STY 19W HAS MAINTAINED INTENSITY OVER APPROXIMATELY THE PAST 18 HOURS SUPPORTED BY LOW VERTICAL WIND SHEAR AND POLEWARD OUTFLOW ALONG THE LEADING EDGE OF THE TROUGH EAST OF JAPAN. THE SYSTEM WILL MAINTAIN INTENSITY OVER THE NEXT 12 HOURS AS IT CONTINUES TO TRACK IN AN ENVIRONMENT OF LOW VERTICAL WIND SHEAR AND EXPERIENCES SOME ENHANCED POLEWARD OUTFLOW ASSOCIATED WITH THE MIDLATITUDE TROUGH EAST OF JAPAN. THE SYSTEM IS FORECAST TO SLOWLY WEAKEN AFTER 12 HOURS AS THE LINKAGE WITH THE MIDLATITUDE TROUGH IS EXPECTED TO BE LOST AND UPPER LEVEL RIDGING INDUCES SUBSIDENCE AND SUPRESSES OUTFLOW ON THE NORTHERN SIDE OF STY 19W. MORE SIGNIFICANT WEAKENING WILL OCCUR BETWEEN TAUS 48 AND 72 AS STY 19W INTERACTS WITH THE TERRIAN OF TAIWAN. D. CURRENT WIND RADII ARE BASED ON A 292104Z QUIKSCAT PASS. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR A SMALL TO MEDIUM SIZED SYSTEM. E. IN THE EXTENDED FORECAST PERIOD, STY 19W WILL TRACK ALONG THE SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE AS THE RIDGE REPOSITIONS EASTWARD AND MAKE LANDFALL ALONG THE EAST COAST OF CHINA. THE SYSTEM WILL DISSIPATE DUE TO LAND INTERACTION OVER CHINA. 3. FORECAST TEAM: ALPHA// NNNN