WDPN32 PGTW 051500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (HAISHEN) WARNING NR 11// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 05W (HAISHEN), LOCATED APPROXIMATELY 115 NM NORTHWEST OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR SATELLITE IMAGERY CONTINUES TO REVEAL A SLIGHTLY EXPOSED LOW LEVEL CIRCULATION CENTER THAT HAS BARELY MOVED OVER THE PAST 6 HOURS. THIS IS CONFIRMED BY A 051047 METOP-A MICROWAVE IMAGE WITH GOOD CONFIDENCE. UPPER-LEVEL ANALYSIS INDICATES AN UNFAVORABLE ENVIRONMENT WITH HIGH (30 TO 40 KNOT) SOUTHWESTERLY VERTICAL WIND SHEAR (VWS) AND SOME POLEWARD OUTFLOW. TS 05W IS CURRENTLY QUASI-STATIONARY UNDER A COMPLEX STEERING ENVIRONMENT. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. THE STEERING ENVIRONMENT FOR TS HAISHEN WILL REMAIN COMPLEX OVER ITS LIFECYCLE. THE STR TO THE NORTHWEST WILL CONTINUE TO BUILD AND PREVENT THE SYSTEM FROM SIGNIFICANT WESTWARD MOVEMENT BEYOND TAU 24. ADDITIONALLY, A NEAR EQUATORIAL RIDGE BUILDING TO THE SOUTHEAST WILL TRY TO FORCE THE SYSTEM TO THE EAST-NORTHEAST. FINALLY, A DEEP MID-LATITUDE TROUGH TO THE NORTHEAST FURTHER COMPLICATES THE STEERING ENVIRONMENT, PREVENTING ANY TRUE POLEWARD MOTION. AS SUCH, TS 05W IS EXPECTED TO REMAIN IN A VERY SLOW NORTHWESTWARD OR QUASI- STATIONARY MOTION. INCREASING VWS THROUGH THE FORECAST PERIOD WILL ERODE THE SYSTEM WITH COMPLETE DISSIPATION BY TAU 48. A WIDE SPREAD IN THE DYNAMIC MODEL GUIDANCE DUE TO THE COMPLEXITY OF THE STEERING MECHANICS LEAD TO AN OVERALL LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN