WDPN31 PGTW 090300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (HAGUPIT) WARNING NR 33// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 22W (HAGUPIT), LOCATED APPROXIMATELY 38 NM SOUTH-SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED WEST- NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS WEAKENING DEEP CENTRAL CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 082333Z F-18 37GHZ MICROWAVE IMAGE HINTS AT SOME CURVED BANDING SOUTHWEST OF MANILA. THE CURRENT POSITION IS BASED ON THE MSI ANIMATION AND MICROWAVE IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 40 KNOTS IS BASED ON THE WEAKENING TREND AND OVERALL CURRENT STRUCTURE. UPPER- LEVEL ANALYSIS INDICATES TS 22W IS LOCATED IN AN AREA OF LOW TO MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR OFFSET BY GOOD POLEWARD OUTFLOW CHANNEL TAPPING INTO THE MID- LATITUDE WESTERLIES. TS 22W IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS HAGUPIT WILL CONTINUE TO TRACK WEST OVER THE NEXT 24 HOURS UNDER THE STEERING INFLUENCE OF THE STR TO THE NORTHEAST. BEYOND THAT, TS 22W IS FORECAST TO SHIFT ITS TRACK TO WEST-SOUTHWESTWARD AS THE RIDGING CURRENTLY LOCATED OVER SOUTHEAST ASIA BUILDS IN NORTH OF THE SYSTEM. EXPECT A WEAKENING TREND AS THE SYSTEM TRACKS ACROSS THE SOUTH CHINA SEA AND INTERACTS WITH THE COOLER AIR ASSOCIATED WITH THE NORTHEASTERLY SURGE EVENT. TS HAGUPIT WILL CONTINUE TO WEAKEN AS IT APPROACHES VIETNAM, LEADING TO DISSIPATION IN SOUTHERN VIETNAM BY THE END OF THE FORECAST PERIOD. MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST WHICH IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN