MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 33// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 173 NM SOUTH- SOUTHEAST OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A DEFINED 9 NM EYE WHILE THE CONVECTIVE SIGNATURE CONTINUES TO BECOME MORE ELONGATED AND RAGGED. A 101842Z SSMI MICROWAVE PASS REVEALS THE OVERALL STRUCTURE OF THE SYSTEM HAS REMAINED FAIRLY SYMMETRIC WHILE THE EYEWALL STRUCTURE HAS STARTED TO DETERIORATE ALONG THE SOUTHERN PORTION OF THE STORM. THE INITIAL POSITION IS BASED ON THE EYE FEATURE ON THE EIR ANIMATION WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 110 KNOTS IS BASED ON AN ASSESSMENT OF DVORAK ESTIMATES FROM MULTIPLE REPORTING AGENCIES AND DUE TO THE WEAKENING STRUCTURE. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF MODERATE (15-20 KNOT) VERTICAL WIND SHEAR (VWS) AND EXCELLENT OUTFLOW WHICH IS BEING ENHANCED ALONG THE POLEWARD SIDE DUE TO THE MID-LATITUDE WESTERLIES. TY 19W HAS STARTED TO TRACK TO THE NORTH-NORTHWEST AS SOME MIGRATORY RIDGING HAS STARTED TO BUILD IN NORTH OF THE SYSTEM. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 19W IS EXPECTED TO TRACK ON A NORTH-NORTHWESTWARD TRAJECTORY OVER NEXT 36 HOURS IN RESPONSE TO THE AFOREMENTIONED SHORTWAVE RIDGE AS IT PASSES TO THE NORTH AND AS THE SUBTROPICAL RIDGE (STR) REMAINS TO THE EAST OF THE SYSTEM. AFTER TAU 36, A MID- LATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL WEAKEN THE SHORTWAVE RIDGE AND PRESS UPON THE STR CAUSING THE CYCLONE TO RECURVE NORTHEASTWARD. CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA- TROPICAL TRANSITION (ETT) AFTER TAU 48 AS IT ACCELERATES NORTHEASTWARD THROUGH SOUTHERN JAPAN AND BEGINS TO GAIN FRONTAL CHARACTERISTICS. AS THE SYSTEM GAINS LATITUDE, INCREASING VWS ASSOCIATED WITH THE MID-LATITUDE WESTERLIES WILL BEGIN A WEAKENING PROCESS. C. AFTER TAU 72, CONTINUED INTERACTION WITH THE MID-LATITUDE WESTERLIES AND JAPANS RUGGED TERRAIN WILL RAPIDLY WEAKEN THE SYSTEM AS THE ETT PROCESS CONTINUES. BY TAU 96, THE SYSTEM IS EXPECTED TO BECOME A GALE-FORCE COLD-CORE LOW EAST OF HOKKAIDO. AVAILABLE MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE TO JTWC TRACK FORECAST THAT IS POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN