MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (CHOI-WAN) WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 23W (CHOI-WAN), LOCATED APPROXIMATELY 158 NM WEST- SOUTHWEST OF MINAMI TORI SHIMA, HAS TRACKED NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A CONSOLIDATING LOW-LEVEL CIRCULATION CENTER (LLCC) WITH IMPROVED CONVECTIVE BANDING WRAPPING TIGHTLY INTO A BROAD BUT DEFINED CENTER. A 052021Z WINDSAT 37GHZ IMAGE SHOWS TIGHTLY-CURVED BANDING WRAPPING INTO A WELL-DEFINED MICROWAVE EYE FEATURE. THE CURRENT POSITION IS BASED ON THE MSI AND MICROWAVE IMAGERY WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS BASED ON THE HIGHER END OF DVORAK INTENSITY ESTIMATES RANGING FROM 55 TO 65 KNOTS. UPPER-LEVEL ANALYSIS SHOWS A FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR (VWS). ADDITIONALLY, WARM SEA SURFACE TEMPERATURES (SSTS) ARE CONDUCIVE FOR FURTHER DEVELOPMENT. TY 23W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP-LAYERED SUB-TROPICAL RIDGE (STR). 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY CHOI-WAN IS STARTING TO ROUND THE SOUTHWESTERN PERIPHERY OF THE STEERING STR AND IS NOW TRACKING ON A POLEWARD TRAJECTORY. FAVORABLE ENVIRONMENTAL CONDITIONS WILL PERSIST FOR THE NEXT 24 TO 36 HOURS, ALLOWING TY 23W TO REACH A PEAK INTENSITY OF 80 KNOTS BEFORE MOVING INTO AN UNFAVORABLE ENVIRONMENT. NEAR TAU 24, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE BAROCLINIC ZONE. TY 23W IS FORECAST TO WEAKEN AS IT ENCOUNTERS STRONG VWS AND TRACKS OVER COOL SST (BELOW 26 CELSIUS). TY CHOI-WAN WILL COMPLETE ETT AS IT GAINS FRONTAL CHARACTERISTICS BY TAU 48 BUT WILL REMAIN A STRONG COLD-CORE LOW AS IT TRACKS NORTHWARD WITH EXPANSIVE GALE-FORCE WINDS, WHICH SHOULD EXTEND AS FAR WEST AS THE NORTHEAST COAST OF HONSHU. DYNAMIC MODEL GUIDANCE REMAINS IN VERY TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN