MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FENGSHEN) WARNING NR 020// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 26W (FENGSHEN), LOCATED APPROXIMATELY 185 NM EAST OF IWO TO, JAPAN, HAS TRACKED NORTHEASTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A SYMMETRIC EYEWALL SURROUNDING A 13-NM RAGGED EYE, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. A 160334Z AMSR2 89GHZ IMAGE, HOWEVER, REVEALS AN ASYMMETRIC CONVECTIVE STRUCTURE WITH DEEP CONVECTIVE BANDING WRAPPING INTO A MICROWAVE EYE FEATURE. UPPER- LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT WITH MODERATE VERTICAL WIND SHEAR (VWS) OFFSET BY ROBUST POLEWARD OUTFLOW. THE INITIAL INTENSITY IS ASSESSED AT 110 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 5.5 TO 6.0 (102 TO 115 KNOTS). TY 26W HAS ROUNDED THE SUBTROPICAL RIDGE (STR) AXIS AND IS ACCELERATING WITHIN THE MIDLATITUDE WESTERLIES. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 26W WILL TRACK EAST-NORTHEASTWARD TO EASTWARD WHILE WEAKENING RAPIDLY UNDER INCREASING, STRONG (40-50 KNOTS) VWS. AFTER TAU 36, TY 26W WILL WEAKEN SIGNIFICANTLY, GRADUALLY SLOW AND TURN SOUTHWARD THEN WESTWARD AS A STRONG LOW-LEVEL HIGH BUILDS TO THE NORTH. THE SYSTEM IS EXPECTED TO DISSIPATE BY TAU 72 WITH THE REMNANTS TRACKING POLEWARD. THE MAJORITY OF THE NUMERICAL MODELS ARE IN GENERAL AGREEMENT WITH THIS LOOPING TRACK BUT WITH SIGNIFICANT DIFFERENCES IN THE TRACK SPEED AND THE TIMING OF THE TURNS. IN VIEW OF THIS COMPLEX STEERING AND THE LARGE VARIANCE IN THE NUMERICAL MODEL SOLUTIONS, THERE IS LOW CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN