MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 34// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 137 NM SOUTH- SOUTHEAST OF KADENA AB, OKINAWA, HAS TRACKED NORTH-NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE EYE FEATURE OF THE SYSTEM HAS BECOME CLOUD FILLED WHILE THE OVERALL STRUCTURE OF THE SYSTEM HAS STARTED TO ELONGATE. A 102119Z SSMIS MICROWAVE PASS REVEALS THE SYSTEM HAS REMAINED TIGHTLY WRAPPED ALTHOUGH THE BULK OF THE DEEP CONVECTION HAS BECOME CONTAINED TO THE NORTHERN SEMI-CIRCLE. THE INITIAL POSITION IS BASED ON THE WEAK EYE FEATURE IN THE MSI ANIMATION ALONG WITH RADAR POSITION FIXES FROM RJTD WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 100 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 INCREASING (15-25 KNOT) VERTICAL WIND SHEAR (VWS) AND STRONG OUTFLOW WHICH IS BEING ENHANCED ALONG THE POLEWARD SIDE DUE TO THE MID-LATITUDE WESTERLIES. TY 19W IS TRACKING TO THE NORTH-NORTHWEST ALONG A SUBTROPICAL RIDGE (STR) TO THE EAST AND A MIGRATORY RIDGE TO THE NORTH. 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 THE NEXT 36 HOURS IN RESPONSE TO THE AFOREMENTIONED MIGRATORY RIDGE AS IT PASSES TO THE NORTH AND AS THE STR REMAINS TO THE EAST OF THE SYSTEM. AFTER TAU 36, A MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST WILL WEAKEN THE RIDGE TO THE NORTH AND PRESS UPON THE STR CAUSING THE CYCLONE TO RECURVE NORTHEASTWARD. CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR 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 CONTINUE TO WEAKEN THE SYSTEM. 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