MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (LAN) WARNING NR 18// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 25W (LAN), LOCATED APPROXIMATELY 523 NM SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED NORTHWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS DEEP BANDING WRAPPING INTO A LARGE, WELL DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). THE SYSTEM REMAINS VERY BROAD, COVERING OVER 900 NM. A 191754Z 85 GHZ SSMI IMAGE SHOWS DEEP CONVECTIVE BANDING WRAPPING INTO A WELL DEFINED MICROWAVE EYE FEATURE. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PREVIOUSLY MENTIONED MICROWAVE EYE FEATURE. THE INITIAL INTENSITY OF 75 KNOTS IS BASED ON DVORAK INTENSITY ASSESSMENTS OF T4.5 (77 KNOTS) FROM BOTH PGTW AND RJTD. ENVIRONMENTAL ANALYSIS INDICATES THAT THE SYSTEM IS IN AN AREA OF LOW (5-15 KNOT) VERTICAL WIND SHEAR (VWS) THAT IS BEING OFFSET BY ROBUST RADIAL OUTFLOW. TYPHOON LAN IS TRACKING THOUGH AN AREA OF VERY WARM (30 TO 31 CELSIUS) SEA SURFACE TEMPERATURES (SSTS) AND HIGH OCEAN HEAT CONTENT. TY 25W IS TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) LOCATED TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 25W IS FORECAST TO TRACK NORTHWARD OVER THE NEXT 12-24 HOURS UNDER THE INFLUENCE OF THE STR. AFTER CROSSING THE RIDGE AXIS AROUND TAU 24, THE SYSTEM WILL BEGIN TO RECURVE BACK TO THE NORTHEAST. FAVORABLE ENVIRONMENTAL CONDITIONS WILL PERSIST AND POLEWARD OUTFLOW WILL BE ENHANCED AS THE SYSTEM APPROACHES THE MID- LATITUDE WESTERLIES. INTERACTION WITH THE WESTERLIES WILL ALLOW FOR A BRIEF PERIOD OF RAPID INTENSIFICATION, REACHING A PEAK INTENSITY OF 105 KNOTS AROUND TAU 36. AFTER TAU 48, THE SYSTEM WILL BEGIN TO GRADUALLY WEAKEN AS VERTICAL WIND SHEAR INCREASES AND THE SYSTEM BEGINS TO INTERACT WITH AN APPROACHING MID-LATITUDE TROUGH. BY TAU 72, TY 25W WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT). DYNAMIC MODEL GUIDANCE IS IN STRONG AGREEMENT, LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, TY LAN WILL ACCELERATE NORTHEASTWARD AS IT BECOMES EMBEDDED IN THE BAROCLINIC ZONE. AROUND TAU 60, THE SYSTEM IS FORECAST TO MAKE A BRIEF LANDFALL NEAR TOKYO. AFTER EXITING BACK INTO THE PACIFIC OCEAN, THE SYSTEM IS FORECAST TO CONTINUE TO TRACK TO THE NORTHEAST AND COMPLETE EXTRA-TROPICAL TRANSITION BY TAU 96, BECOMING A HURRICANE-FORCE COLD CORE LOW WITH AN EXPANSIVE WIND FIELD. INCREASING VWS AND THE SYSTEM TRACKING THROUGH AN AREA OF COOLER (<26 CELSIUS) SEA SURFACE TEMPERATURES WILL CONTINUE TO WEAKEN THE SYSTEM FOR THE DURATION OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT DIRECTION-WISE, HOWEVER, VARIATIONS IN THE TRACK SPEED AFTER TAU 72 LEAD TO A SIGNIFICANT SPREAD BY TAU 120. DUE TO THE UNCERTAINTY IN STORM SPEED AND SPREAD IN THE MODEL GUIDANCE, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST.// NNNN NNNN