MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (TALIM) WARNING NR 27// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 20W (TALIM), LOCATED APPROXIMATELY 170 NM WEST-NORTHWEST OF KADENA AB, HAS TRACKED EAST-NORTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD AND RAGGED EYE FEATURE WITH LITTLE IMPROVEMENT IN THE CONVECTIVE STRUCTURE OVER THE LAST SIX HOURS. A 150657Z SSMIS PASS SHOWS AN ELONGATED LOW-LEVEL STRUCTURE WITH THE UPPER-LEVEL EYE DISPLACED APPROXIMATELY 30 NM TO THE NORTHWEST AND DEEP CONVECTION CONFINED TO THE WESTERN SEMICIRCLE. THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION DUE TO THE DISCREPANCY IN AGENCY SATELLITE FIXES AND THE OBSERVED LOW-LEVEL STRUCTURE OBSERVED IN THE AFOREMENTIONED 37GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 80 KNOTS, BASED ON PERSISTENCE FROM THE PREVIOUS FORECAST WITH NO SIGNIFICANT CHANGES IN CONVECTIVE STRUCTURE OR SUBJECTIVE DVORAK ESTIMATES. UPPER-LEVEL ANALYSIS SHOWS MODERATE TO FAVORABLE VERTICAL WIND SHEAR ASSOCIATED WITH A BUILDING RIDGE TO THE SOUTHEAST HINDERING EQUATORWARD OUTFLOW. POLEWARD OUTFLOW REMAINS ROBUST FEEDING INTO THE MID-LATITUDE JET. DUE TO THE QUASI-STATIONARY MOTION OF TY 20W OVER THE LAST 24 HOURS, OCEAN UPWELLING HAS BROUGHT COOLER WATERS TO THE SURFACE LEADING TO A WEAKENING TREND. HOWEVER, THE WEAKENING TREND APPEARS TO HAVE STABILIZED AS TY 20W IS NOW ACCELERATING EAST-NORTHEASTWARD AROUND A DEEP-LAYERED SUBTROPICAL RIDGE TO THE SOUTHWEST. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, THE INTENSITY IS ELEVATED TO 80 KNOTS JUST PRIOR TO MAKING LANDFALL SOUTHEAST OF SASEBO, JAPAN. B. TY 20W WILL CONTINUE TO TRACK EAST-NORTHEASTWARD ALONG THE NORTHWESTWARD PERIPHERY OF THE SUBTROPICAL RIDGE. SSTS IN THE REGION ARE EXPECTED TO IMPROVE AS THE SYSTEM MOVES AWAY FROM THE AREA OF UPWELLED WATER. UPPER-LEVEL CONDITIONS WILL REMAIN NEUTRAL FOR THE NEXT 36 TO 48 HOURS AS ENHANCED POLEWARD OUTFLOW TAPPING INTO A DEEPENING MID-LATITUDE TROUGH COMPETES WITH MODERATE SOUTHERLY WIND SHEAR ASSOCIATED WITH THE UPPER-LEVEL SUBTROPICAL RIDGE. THE INTENSITY IS FORECAST TO REMAIN STEADY AROUND 80 KNOTS OVER THE NEXT 48 HOURS AS THE SYSTEM MAKES LANDFALL SOUTHEAST OF SASEBO, JAPAN AROUND TAU 42. AROUND TAU 48 THE UPPER-LEVEL TROUGH WILL BEGIN INTERACTING WITH TY 20W INCREASING VERTICAL WIND SHEAR COUPLED WITH STRONG BAROCLINIC SUPPORT. TY 20W WILL TRANSITION INTO A SIGNIFICANT EXTRATROPICAL LOW BY TAU 72. DYNAMIC MODEL GUIDANCE SHOWS VERY TIGHT GROUPING THROUGH THE 72 HOUR FORECAST, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.// NNNN NNNN