WDPN31 PGTW 281500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TAPAH) WARNING NR 05// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 06W (TAPAH), LOCATED APPROXIMATELY 121 NM SOUTHEAST OF SAIPAN, HAS TRACKED NORTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS DECREASING CENTRAL CONVECTION AND AN OVERALL DECREASE IN CONVECTIVE ORGANIZATION. HOWEVER, GUAM RADAR IMAGERY CONTINUES TO INDICATE TIGHTLY-CURVED BANDING WRAPPING INTO A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC). A 281117Z METOP-B 89 GHZ IMAGE DEPICTS A WELL-DEFINED CENTER LOCATED ON THE WESTERN EDGE OF THE DEEP CENTRAL CONVECTION. DESPITE THE GENERAL WEAKENING TREND, A 281118Z ASCAT SHOWS 45 TO 50 KNOT WINDS, WHICH SUPPORTS THE CURRENT INTENSITY OF 50 KNOTS. BASED ON THE RADAR AND MICROWAVE IMAGERY, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LOW (05 TO 10 KNOTS) VERTICAL WIND SHEAR (VWS) AND GOOD POLEWARD OUTFLOW; HOWEVER, POLEWARD OUTFLOW IS WEAKENING AS THE DEEP MIDLATITUDE LOW QUICKLY SHIFTS NORTHEASTWARD. TS 06W IS BEGINNING TO TRACK NORTHWARD AND PERHAPS EVEN NORTH- NORTHWESTWARD AS THE SUBTROPICAL RIDGE (STR) BUILDS IN NORTHEAST OF THE SYSTEM. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 06W IS FORECAST TO TRACK NORTHWARD THROUGH TAU 12 THEN NORTH-NORTHWESTWARD TO NORTHWESTWARD ALONG THE SOUTHWEST PERIPHERY OF THE BUILDING STR TO THE NORTH. TS 06W IS FORECAST TO INTENSIFY FOR THE NEXT 24 HOURS AS FAVORABLE ENVIRONMENTAL CONDITIONS OF GOOD POLEWARD OUTFLOW AND WARM SEA SURFACE TEMPERATURES (NEAR 28 DEGREES CELSIUS) PERSIST. AFTER TAU 24, POLEWARD OUTFLOW IS FORECAST TO WEAKEN AS AN UPPER-LEVEL RIDGE BUILDS SOUTH OF JAPAN. C. IN THE EXTENDED TAUS, TS 06W IS FORECAST TO RE-CURVE AHEAD OF AN APPROACHING SHORTWAVE TROUGH AND SHOULD ENCOUNTER INCREASING VERTICAL WIND SHEAR, DECREASING SEA SURFACE TEMPERATURES, AND BEGIN TO INTERACT WITH THE BAROCLINIC ZONE AT WHICH POINT THE SYSTEM IS FORECAST TO QUICKLY WEAKEN AND DISSIPATE BY TAU 96. THE DYNAMIC MODEL GUIDANCE IS NOW IN GOOD AGREEMENT, THEREFORE, THE FORECAST IS POSITIONED NEAR THE MULTI-MODEL CONSENSUS AND IS CONSISTENT WITH THE PREVIOUS JTWC FORECAST. DUE TO THE TIGHT GROUPING OF MODEL GUIDANCE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN