MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (DOLPHIN) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 14W (DOLPHIN), LOCATED APPROXIMATELY 651 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH- NORTHEASTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MST) DEPICTS TIGHT CURVED BANDING WRAPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE CONVECTIVE FEATURES IN THE MSI LOOP. THE INITIAL INTENSITY OF 45 KTS IS PLACED WITH FAIR CONFIDENCE BASED ON A PGTW DVORAK CURRENT INTENSITY ESTIMATE OF T3.0 (45 KTS). THE SYSTEM CONTINUES TO EXHIBIT BOTH TROPICAL AND SUBTROPICAL CHARACTERISTICS. THE WIND FIELD, CONVECTIVE AND THERMAL STRUCTURES HAVE REMAINED TROPICAL OVER THE PAST 6 HOURS, HOWEVER THE POLEWARD OUTFLOW REMAINS STRONGLY ASSOCIATED WITH THE WESTERLY FLOW OF THE JET THAT IS PLACED OVER HONSHU, JAPAN. SEA SURFACE TEMPERATURES (SST) REMAIN WARM (30-31 CELSIUS) AND CONDUCIVE FOR FURTHER DEVELOPMENT HOWEVER MODERATE (15-20KT) VERTICAL WIND SHEAR HAS PERSISTED. THIS HIGHER VWS, ALONG WITH SUBSIDENCE ALONG THE NORTHWEST PERIPHERY OF THE SYSTEM ASSOCIATED WITH A SHORTWAVE TROUGH TO THE NORTH, ARE OFFSETTING THE OUTFLOW AND WARM SSTS, RESULTING IN AN OVERALL MARGINALLY FAVORABLE ENVIRONMENT. THE CYCLONE IS TRANSITING OUT OF THE COL BETWEEN THE SUBTROPICAL RIDGE (STR) POSITIONED TO THE WEST AND THE STR TO THE EAST, WHICH WILL BECOME THE PRIMARY STEERING MECHANISM. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS DOLPHIN WILL CONTINUE TO TRACK NORTHWARD THROUGH TAU 36 ALONG THE WESTERN PERIPHERY OF THE STEERING STR TO THE EAST AND BEGIN A GENERALLY NORTHEASTWARD TRACK THEREAFTER UPON ROUNDING THE STR AXIS. BY TAU 48 THE SYSTEM WILL REACH A PEAK INTENSITY OF 60 KTS DUE TO THE CONTINUED MARGINALLY FAVORABLE ENVIRONMENT. DURING THIS INITIAL PORTION OF THE FORECAST, THE SYSTEM WILL LIKELY TAKE ON ADDITIONAL SUBTROPICAL CHARACTERISTICS AS SST DECREASES, VWS INCREASES AND THE UPPER LEVEL OUTFLOW BECOMES MORE STRONGLY ASSOCIATED WITH THE ROBUST WESTERLY FLOW ASSOCIATED WITH THE AFOREMENTIONED JET. ENVIRONMENTAL CONDITIONS AFTER TAU 48 WILL DEGRADE DUE TO HIGHER (30+ KTS) VWS, LEADING TO A GRADUAL WEAKENING TO 50 KTS BY TAU 72 AT WHICH POINT THE SYSTEM WILL COMPLETE ETT UPON BECOMING EMBEDDED IN THE DEEP WESTERLY FLOW. NUMERICAL MODEL SOLUTIONS CONTINUE TO DIVERGE SIGNIFICANTLY WITH GFS SOLUTIONS (BOTH ENSEMBLE AND DETERMINISTIC) BRINGING THE VORTEX SOUTH OF HONSHU AND ECMWF, UKMET AND AFUM BRINGING THE TRACK OVER MAINLAND JAPAN. THE JTWC FORECAST TRACK IS PLACED BETWEEN THESE MODEL SOLUTIONS AND CLOSE TO THE MULTI-MODEL CONSENSUS. THE LARGE DEGREE OF SPREAD IN MODEL SOLUTIONS LENDS POOR CONFIDENCE IN THE OVERALL JTWC FORECAST TRACK.// NNNN NNNN