MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (MELOR) WARNING NR 18// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 28W (MELOR), LOCATED APPROXIMATELY 64 NM WEST-SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON A 151800Z PGTW SATELLITE FIX AND A 151756Z AMSU-B IMAGE. THE CURRENT INTENSITY OF 85 KNOTS IS CONSISTENT WITH A CONSENSUS OF DVORAK INTENSITY ESTIMATES FROM MULTIPLE REPORTING AGENCIES. TY 28W HAS EMERGED INTO THE SOUTH CHINA SEA AND IS ENCOUNTERING A REGION OF STRONG NORTHEASTERLY LOW-LEVEL FLOW ASSOCIATED WITH A DEVELOPING COLD SURGE. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS MOVING INTO A LESS FAVORABLE ENVIRONMENT WITH MODERATE TO STRONG (20 TO 30 KNOTS) VERTICAL WIND SHEAR (VWS). ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES A STEADY WEAKENING TREND, WITH DEEP CONVECTION BECOMING LESS ORGANIZED AND SHEARED TO THE NORTHEAST OF THE SYSTEM. A DEEP LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST REMAINS THE PRIMARY STEERING INFLUENCE. 3. FORECAST REASONING. A. THE TRACK FORECAST HAS BEEN SHIFTED SLIGHTLY SOUTH TO INCREASE CONSISTENCY WITH THE MAJORITY OF DYNAMIC MODEL GUIDANCE AND THE MULTI-MODEL CONSENSUS. THE INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD TO ACCOUNT FOR THE OBSERVED RAPID WEAKENING TREND AND ANTICIPATED UNFAVORABLE ENVIRONMENT. B. TY MELOR WILL CONTINUE TO TRACK WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR FOR THE NEXT 12 HOURS AND SLOW AS IT ENTERS A WEAKNESS BETWEEN THE CURRENT STEERING RIDGE AND A SECOND RIDGE TO THE WEST. AS THE SYSTEM MOVES INTO THE WEAKNESS IT IS EXPECTED TO WEAKEN STEADILY, AND TURN SHARPLY TO THE SOUTHWEST FOLLOWING THE STRONG NORTHEASTERLY SURGE AFTER TAU 12. STRONG VWS VALUES AND ENTRAINMENT OF COOLER AND DRIER AIR WILL CONTINUE TO RAPIDLY WEAKEN TY 28W AS IT BECOMES FULLY EMBEDDED WITHIN THE COLD SURGE, AND DISSIPATE BY TAU 72. NUMERICAL MODELS ARE IN GOOD AGREEMENT REGARDING THE EXPECTED TRACK. THE CURRENT OFFICIAL TRACK FORECAST LIES CLOSE TO THE MULTI-MODEL CONSENSUS, WITH HIGH CONFIDENCE.// NNNN NNNN