WDPN31 PGTW 051500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 13W (SOUDELOR) WARNING NR 26// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 13W (SOUDELOR), LOCATED APPROXIMATELY 474 NM SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY CONTINUES TO SHOW THINNING CONVECTION ON THE NORTHERN SEMI-CIRCLE AND A 25 NM DIAMETER EYE THAT SUPPORTS THE HIGH CONFIDENCE IN THE CURRENT POSITION. THE INITIAL INTENSITY OF 100 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES AND REFLECTS THE WEAKENED STATE OF THE SYSTEM. UPPER-LEVEL ANALYSIS INDICATES TY 13W IS LOCATED IN AN AREA OF LOW VWS AND GOOD DIFFLUENCE ALOFT WITH A STRONG EQUATORWARD BIAS. TY SOUDELOR IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED STR TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 13W WILL CONTINUE ON A WESTWARD TRAJECTORY THROUGH TAU 72 UNDER THE STEERING INFLUENCE OF THE STR. TY SOUDELOR WILL SLOWLY WEAKEN OVER THE NEXT 12 HOURS AS THE SUBSIDENCE REMAINS ON THE NORTHERN SIDE. AFTERWARD, EXPECT THE SYSTEM TO GRADUALLY INCREASE IN INTENSITY DUE TO IMPROVED ENVIRONMENTAL CONDITIONS AND ENHANCED POLEWARD OUTFLOW WITH A SECONDARY PEAK OF 120 KNOTS AT TAU 48. THE SYSTEM IS FORECAST TO WEAKEN AS IT TRACKS OVER CENTRAL TAIWAN AND EMERGES INTO THE TAIWAN STRAIT BY TAU 72. C. IN THE EXTENDED TAUS, TY SOUDELOR WILL CONTINUE TO DETERIORATE AS IT TRACKS FURTHER INLAND. CONCURRENTLY, A MIGRATORY MID-LATITUDE TROUGH PASSING TO THE NORTH WILL WEAKEN THE STR AND DRIVE THE CYCLONE POLEWARD. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN