WDPN31 PGTW 270300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (BOPHA) WARNING NR 06// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM 26W (BOPHA), LOCATED APPROXIMATELY 295 NM SOUTHEAST OF CHUUK, FSM, HAS TRACKED WEST-NORTHWESTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A DEEP CENTRALIZED CONVECTIVE COVER HAS DEVELOPED OVER THE LOW LEVEL CIRCULATION CENTER (LLCC) DURING THE PAST SIX HOURS. THE INTENSITY FOR THE SYSTEM HAS BEEN INCREASED TO 35 KNOTS MAKING IT A TROPICAL STORM. THIS IS BASED ON 2.5/2.5 DVORAK ESTIMATES FROM PGTW AND RJTD INDICATING 35 KNOTS. UPPER LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE CONTINUES TO BUILD OVER THE LLCC, PROVIDING FAVORABLE RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR (VWS) (05 TO 10 KNOTS). TS 26W IS LOCATED ON THE SOUTHEASTERN QUADRANT OF A DEEP LAYERED SUBTROPICAL RIDGE (STR) AND REMAINS ON A SLOW WESTWARD TRACK UNDER ITS INFLUENCE. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 26W IS EXPECTED TO TRACK MORE QUICKLY WESTWARD UNDER THE IMPROVING STEERING INFLUENCE OF THE STR. A STEADY INTENSIFICATION OF THE SYSTEM THROUGH TAU 72 IS EXPECTED UNDER A FAVORABLE ENVIRONMENT, LOW VWS, GOOD RADIAL OUTFLOW, AND SEA SURFACE TEMPERATURES BETWEEN 29 TO 30 DEGREES CELSIUS ALONG TRACK. C. IN THE EXTENDED PERIOD, TS 26W WILL REMAIN ON A STEADY TRACK WESTWARD THROUGH TAU 96. A MORE MERIDIONAL PATTERN IS EXPECTED TO DEVELOP BY TAU 120 ALLOWING A SLIGHT WEAKNESS ALONG THE WESTERN EXTENT OF THE STR AS THE STR SHIFTS EASTWARD. INTENSITY WILL STEADILY INCREASE UNDER THE INFLUENCE OF THE PERSISTENT FAVORABLE ENVIRONMENT. MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE WESTWARD TRACK, WITH THE EXCEPTION OF GFS AND ECMF. BOTH INDICATE A MORE WEST- NORTHWEST TRACK INTO THE STR. THIS FORECAST IS MORE IN LINE WITH THE CONSENSUS OF AVAILABLE GUIDANCE, KEEPING THE TRACK FURTHER SOUTH THAN DEPICTED BY GFS AND ECMF. CONFIDENCE IN THE TRACK FORECAST REMAINS LOW AS THE LLCC REMAINS WITHIN A WEAK STEERING REGION OF THE STR.// NNNN