MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TAPAH) WARNING NR 06// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 06W (TAPAH), LOCATED APPROXIMATELY 99 NM EAST OF SAIPAN, HAS TRACKED NORTHWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED OVERALL ORGANIZATION AS THE CENTRAL CONVECTION SLIGHTLY DEEPENED. ADDITIONALLY, GUAM DOPPLER RADAR IMAGERY CONTINUES TO INDICATE TIGHTLY-CURVED BANDING WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER THAT IS NOW AT THE EDGE OF EFFECTIVE RADAR RANGE. THE INITIAL POSITION IS BASED ON THE ABOVE IMAGES WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS BASED ON THE 281730Z DVORAK ESTIMATE FROM PGTW. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW (05 TO 10 KNOT) VERTICAL WIND SHEAR (VWS) AND GOOD POLEWARD OUTFLOW; HOWEVER, POLEWARD OUTFLOW IS WEAKENING AS THE DEEP MID-LATITUDE LOW QUICKLY SHIFTS NORTHEASTWARD. TS 06W IS TRACKING NORTHWARD ALONG THE WESTERN EDGE OF A MID-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 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 AS THE STR IS EXPECTED TO SLIGHTLY BUILD. 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 NORTHEASTWARD AHEAD OF AN APPROACHING SHORTWAVE TROUGH AND SHOULD ENCOUNTER INCREASING VWS, DECREASING SEA SURFACE TEMPERATURES. THE SYSTEM SHOULD ALSO BEGIN INTERACTING WITH THE COLD BAROCLINIC ZONE AT WHICH POINT THE SYSTEM IS FORECAST TO QUICKLY ERODE, DISSIPATING BY TAU 96. THE DYNAMIC MODEL GUIDANCE REMAINS IN GOOD AGREEMENT. THE TRACK FORECAST IS LAID EAST OF THE MULTI-MODEL CONSENSUS TO OFFSET UNLIKELY WESTWARD OUTLIERS. DUE TO THE TIGHT GROUPING OF MODEL GUIDANCE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. // NNNN NNNN