WDPN32 PGTW 110900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (VAMCO) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 25W (VAMCO), LOCATED APPROXIMATELY 139 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM CONTINUED TO INTENSIFY AS EVIDENCED BY A MORE COMPACT SIGNATURE, INCLUDING FEEDER BANDS THAT WRAPPED TIGHTER INTO THE CENTRAL CONVECTION THAT HAS MAINTAINED A DEFINED, ALBEIT CLOUD-FILLED, 15-NM EYE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A SHARPLY-OUTLINED LOW LEVEL CIRCULATION CENTER ON A COMPOSITE RADAR LOOP FROM PAGASA THAT LINED UP WELL WITH THE EYE FEATURE IN THE MSI, ADJUSTED FOR A SLIGHT POLEWARD TILT. THE INITIAL INTENSITY OF 80KTS IS AVERAGED FROM A CIMSS SATCON ESTIMATE OF 85KTS AND THE PGTW DVORAK ESTIMATE OF T4.5/77KTS, 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. 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. AS THE STR BUILDS, TY 25W WILL CONTINUE TO TRACK GENERALLY ON A WESTWARD TRAJECTORY TOWARD CENTRAL LUZON, MAKING LANDFALL OVER THE PROVINCE OF BULACAN AROUND TAU 09, DRAG ACROSS PAMPANGA AND ZAMBALES, BEFORE EXITING INTO THE SOUTH CHINA SEA (SCS) NEAR TAU 18. THE FAVORABLE ENVIRONMENT WILL FUEL FURTHER INTENSIFICATION TO A PEAK OF 85-90KTS OVER THE NEXT 6HRS (NOT CAPTURED IN THE JTWC WARNING TEXT AND GRAPHIC) BEFORE MAKING LANDFALL. AFTERWARD, 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 75KTS BY TAU 48. AFTERWARD, COOLING SST AND DECREASING OCEAN HEAT CONTENT (OHC) IN THE WESTERN SCS WILL WEAKEN TY 25W TO 60KTS 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 LAID NEAR THE MULTI- MODEL CONSENSUS. C. AFTER TAU 72, TY VAMCO WILL TRACK WEST-NORTHWESTWARD AS THE STR IS WEAKENED BY AN APPROACHING MIDLATITUDE TROUGH TO THE NORTH, MAKING LANDFALL OVER CENTRAL VIETNAM, JUST NORTH OF HUE, SHORTLY AFTER TAU 96. SST DROPS TO 27C AND OHC DOWN TO 25KJ/CM^2 NEAR VIETNAM CAUSING FURTHER WEAKENING TO 30KTS BY LANDFALL. AFTERWARD, THE RUGGED INDO-CHINA PENINSULA WILL RAPIDLY ERODE AND DISSIPATE THE SYSTEM BY TAU 120 AFTER IT CROSSES INTO CENTRAL LAOS. NUMERICAL MODELS GRADUALLY AND EVENLY SPREAD TO OVER 220NM BY TAU 120, LENDING FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK THAT IS PLACED NEAR THE MULTI-MODEL CONSENSUS.// NNNN