MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (TEN) WARNING NR 02// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 10W (TEN), LOCATED APPROXIMATELY 193 NM WEST- NORTHWEST OF YAP, HAS TRACKED NORTH-NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A STEADY INCREASE IN CENTRALIZED DEEP CONVECTION WITH DEVELOPING BANDS WRAPPING ALONG THE SOUTHERN AND EASTERN QUADRANTS OF THE SYSTEM. THE CURRENT INTENSITY OF 35 KNOTS IS BASED ON DVORAK ESTIMATES FROM PGTW AND RJTD. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN A MARGINAL ENVIRONMENT WITH MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR (VWS), WHICH IS PROVIDING EXCELLENT EQUATORWARD OUTFLOW, EVIDENT IN ANIMATED WATER VAPOR IMAGERY. TS 10W IS CURRENTLY POSITIONED IN A WEAK STEERING ENVIRONMENT BETWEEN A DEEP-LAYER SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH AND A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 10W IS EXPECTED TO TRACK SLOWLY NORTHWARD WITHIN THE WEAK STEERING ENVIRONMENT THROUGH TAU 24. AFTER TAU 24 THE STR IS FORECAST TO BECOME THE DOMINANT STEERING INFLUENCE AS THE NER WEAKENS. TRACK SPEEDS WILL PICK UP AFTER TAU 36 TRACKING THE SYSTEM TO THE NORTHWEST. VWS WILL REMAIN AT MODERATE LEVELS THROUGH TAU 48, WHICH WILL INHIBIT STRONG INTENSIFICATION, BUT TS 10W IS EXPECTED TO STRENGTHEN WITH THE VERY FAVORABLE SEA SURFACE TEMPERATURES AND HIGH OCEAN HEAT CONTENT ALONG THE FORECAST TRACK. BEYOND TAU 48 THE VWS WILL DECREASE, ALLOWING FOR FURTHER INTENSIFICATION. THE TRACK WILL REMAIN ON A GENERAL NORTHWEST TRACK THROUGH TAU 72 ALONG THE SOUTHWESTERN QUADRANT OF THE DEEP LAYERED STR. C. IN THE EXTENDED TAUS, A DIGGING MID-LATITUDE TROUGH WILL CAUSE THE STR TO WEAKEN OVER SOUTHERN JAPAN, WITH THE POSSIBILITY OF TWO SEPARATE STRS TO DEVELOP. AS THE TROUGH MOVES EASTWARD, THE TWO STRS ATTEMPT TO BUILD BACK OVER SOUTHERN JAPAN. BETWEEN TAU 96 AND 120 MODEL GUIDANCE IS SPLIT BETWEEN A TURN NORTHWARD (GFS, COAMPS, GFDN) AND A CONTINUED NORTHWEST TRACK TOWARDS NORTHERN TAIWAN (NAVGEM, ECMWF). THIS FORECAST FAVORS A SLIGHT TURN NORTHWARD, REMAINING MORE WITH THE CONSENSUS OF MODEL GUIDANCE. THE ENVIRONMENT WILL REMAIN FAVORABLE FOR DEVELOPMENT THROUGH TAU 120, WITH A MAXIMUM INTENSITY FORECAST TO BE 95 KNOTS. DUE TO THE SLOW AND/OR ERRATIC MOVEMENT IN THE NEAR TERM AND THE UNCERTAINTY OF THE TRACK AT EXTENDED TAUS, THE CONFIDENCE IN THE FORECAST TRACK REMAINS AT LOW CONFIDENCE.// NNNN NNNN