MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN) WARNING NR 024// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 166 NM NORTH-NORTHEAST OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED EASTWARD AT 28 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A RAPIDLY WEAKENING SYSTEM WITH ISOLATED DEEP CONVECTION SHEARED EAST OF THE DECOUPLED LOW-LEVEL CIRCULATION CENTER (LLCC). VISIBLE SATELLITE IMAGERY INDICATES A WELL-DEFINED, FULLY-EXPOSED LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 60 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF T3.5/4.0 (55/65 KNOTS) AND A 17/0704Z CIMSS SATCON ESTIMATE OF 57 KNOTS, CONSISTENT WITH THE TIGHTLY-CURVED SHALLOW BANDING STRUCTURE EVIDENT IN A 170423Z SSMI 37GHZ MICROWAVE IMAGE. TS 26W IS DECAYING RAPIDLY WITHIN A HOSTILE ENVIRONMENT WITH STRONG (40-50 KNOTS) WEST-SOUTHWESTERLY VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT. THE SYSTEM IS TRACKING ON THE POLEWARD SIDE OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 12 HOURS, TS 26W WILL CONTINUE RAPIDLY WEAKENING WITHIN THE HOSTILE ENVIRONMENT AND IS FORECAST TO SLOW SIGNIFICANTLY AS A STRONG LOW-LEVEL HIGH BUILDS QUICKLY NORTH OF THE SYSTEM. AFTER TAU 12, TS 26W WILL TURN SOUTHWARD TO WESTWARD AS IT STEERS UNDER THE DOMINANT LOW-LEVEL HIGH POSITIONED TO THE NORTH. TS 26W SHOULD DISSIPATE BETWEEN TAU 36 TO TAU 48. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT, THEREFORE, THERE IS MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN