WDPN32 PGTW 111500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (VAMCO) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 25W (VAMCO), LOCATED APPROXIMATELY 110 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO INTENSIFY AS EVIDENCED BY COOLING CONVECTIVE TOPS OVER THE EYEWALL SURROUNDING A PINHOLE 10-NM DEFINED EYE, EVEN AS ITS WESTERN RAIN BANDS ARE NOW SWEEPING ACROSS THE PHILIPPINE ARCHIPELAGO. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE THAT LINED UP WELL WITH A SHARPLY-OUTLINED CIRCULATION CENTER ON A COMPOSITE RADAR LOOP FROM PAGASA. THE INITIAL INTENSITY OF 90KTS IS BASED ON THE PGTW DVORAK ESTIMATE OF T5.0/90KTS AND SATCON ESTIMATE OF 88KTS, AND REFLECTS THE 6-HR INTENSIFICATION. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM REMAINS IN A FAVORABLE AREA WITH LOW (05-10KT) VERTICAL WIND SHEAR (VWS) AND STRONG RADIAL OUTFLOW ASSOCIATED WITH A POINT SOURCE DIRECTLY OVERHEAD. ADDITIONALLY, SEA SURFACE TEMPERATURES (SST) IN THE PHILIPPINE SEA REMAIN WARM AND FAVORABLE AT 29-30C. HOWEVER, THE SYSTEM IS NOW POISED TO MAKE LANDFALL INTO THE RUGGED TERRAIN OF LUZON. THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 25W WILL CONTINUE ON ITS CURRENT TRACK TOWARD CENTRAL LUZON, MAKING LANDFALL OVER THE PROVINCE OF BULACAN AROUND TAU 06, DRAG ACROSS PAMPANGA AND ZAMBALES, BEFORE EXITING INTO THE SOUTH CHINA SEA (SCS) SHORTLY AFTER TAU 12. AFTERWARD, AS THE STR BUILDS, IT WILL TRACK MORE WESTWARD. LAND INTERACTION WILL MAINLY WEAKEN IT TO 65KTS BY TAU 24 AFTER IT EXITS IN THE SCS. THE WARM WATERS OF THE SCS (29C) AND FAVORABLE VWS WILL FUEL A GRADUAL INTENSIFICATION TO A SECONDARY PEAK OF 70KTS AT TAUS 36-48. AFTERWARD, TY 25W WILL TRACK MORE WEST-NORTHWESTWARD, AS THE STR IS WEAKENED BY AN APPROACHING MIDLATITUDE TROUGH TO THE NORTH, OVER COOLING SST AND DECREASING OCEAN HEAT CONTENT (OHC) IN THE WESTERN SCS THAT WILL WEAKEN IT TO 45KTS BY TAU 72 AS IT APPROACHES VIETNAM. NUMERICAL MODELS ARE IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK WHICH IS PLACED NEAR THE MULTI- MODEL CONSENSUS. C. AFTER TAU 72, TY VAMCO WILL CONTINUE ON A WEST-NORTHWESTWARD TRACK, MAKING LANDFALL OVER CENTRAL VIETNAM, JUST NORTH OF HUE, AROUND TAU 90. SST DROPS TO 27C AND OHC DOWN TO 25KJ/CM^2 NEAR VIETNAM. THESE, PLUS THE RUGGED TERRAIN WILL RAPIDLY ERODE THE SYSTEM TO 25 KTS BY TAU 96 AFTER LANDFALL, THEN TO EVENTUAL DISSIPATION BY TAU 120 AFTER IT CROSSES INTO CENTRAL LAOS. NUMERICAL MODELS GRADUALLY AND EVENLY SPREAD TO OVER 500NM BY TAU 120, WITH AFUM AS THE NOTABLE RIGHT OUTLIER, OFFERING AN UNLIKELY U-TURN TRACK OVER HAINAN. THERE IS OVERALL FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK THAT IS PLACED JUST LEFT OF THE MULTI-MODEL CONSENSUS TO OFFSET AFUM.// NNNN