MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 18W (PHANFONE) WARNING NR 25// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 18W (PHANFONE), LOCATED APPROXIMATELY 373 NM SOUTH OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A 30-NM RAGGED EYE WITH SLIGHTLY WEAKENED SPIRAL BANDING. A 041715Z NOAA-19 MICROWAVE IMAGE SHOWS A ROUND SIGNATURE WITH A WELL- DEFINED MICROWAVE EYE. THE CURRENT POSITION IS BASED ON THE EYE FEATURE ON EIR ANIMATION AND MICROWAVE IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 110 KNOTS IS BASED ON MATCHING DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES. UPPER-LEVEL ANALYSIS INDICATES TY 18W IS LOCATED IN AN AREA OF STRONG (GREATER THAN 30 KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY VIGOROUS OUTFLOW, ESPECIALLY ON THE POLEWARD SIDE THAT IS BEING ENHANCED BY THE MID- LATITUDE WESTERLIES. ADDITIONALLY, THERE IS A POINT-SOURCE DIRECTLY OVER THE SYSTEM SUSTAINING THE CURRENT CONVECTION AND INTENSITY. TY 18W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP- LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 18W IS FORECAST TO TRACK NORTHWARD OVER THE NEXT 06 HOURS AS IT ROUNDS THE WESTERN PERIPHERY OF THE STR AND WILL ACCELERATE NORTHEASTWARD AS IT STARTS EXTRA-TROPICAL TRANSITION. TY 18W IS EXPECTED TO BE QUICKLY ABSORBED INTO THE BAROCLINIC ZONE. INCREASING VWS AND COOLING SEA SURFACE TEMPERATURES WILL RAPIDLY ERODE THE SYSTEM BUT WILL STILL BE A VERY INTENSE STORM FORCE COLD-CORE LOW BY TAU 48. THE AVAILABLE NUMERIC GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID SLIGHTLY TO THE RIGHT OF AND FASTER THAN MULTI-MODEL CONSENSUS.// NNNN NNNN