MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR 024// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 19W (MITAG), LOCATED APPROXIMATELY 57 NM EAST-SOUTHEAST OF KUNSAN AB, HAS TRACKED NORTHEASTWARD AT 18 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS AN ELONGATED AND POORLY DEFINED LOW LEVEL CIRCULATION CENTER WITH CONVECTION SHEARED TO THE NORTHEAST.THE SHEARED CONVECTION AND INITIAL FRONTAL FEATURES INDICATE THAT THE SYSTEM IS UNDERGOING EXTRATROPICAL TRANSITION (ETT). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE DUE TO THE ELONGATED NATURE OF THE LLCC BASED ON THE MSI LOOP AND JMA RADAR IMAGERY. THE INITIAL INTENSITY OF 40 KNOTS IS BASED ON SURFACE OBSERVATIONS IN THE VICINITY OF THE SYSTEM. THE STRONGEST WIND OBSERVATIONS ARE FROM OBSERVATION STATIONS THAT ARE OVER 50 NM FROM THE INITIAL POSITION ON ULLEUNGDO ISLAND, SOUTH KOREA. THE MID-LATITUDE JET IS ENHANCING POLEWARD OUTFLOW, CREATING A STRONG OUTFLOW CHANNEL. THE GOOD OUTFLOW IS BEING OFFSET BY STRONG (30-40 KT) VERTICAL WIND SHEAR AND LAND INTERACTION MAKING THE ENVIRONMENT OVERALL UNFAVOURABLE. TS 19W IS TRACKING INTO THE MID-LATITUDE WESTERLIES ON THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED TO THE SOUTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 12 HOURS, TS 19W WILL SHIFT ONTO A MORE EAST-NORTHEASTWARD TRACK AS IT CONTINUES TO ROUND THE STR. THE SYSTEM WILL CONTINUE ETT AS IT MOVES DEEPER INTO THE MID-LATITUDE WESTERLIES. ETT SHOULD COMPLETE AROUND TAU 24 AS THE SYSTEM TRACKS ACROSS THE SEA OF JAPAN. SHORTLY THEREAFTER, 19W WILL MAKE LANDFALL OVER NORTHERN HONSHU, TRACKING SOUTH OF MISAWA. THE 48 HOUR FORECAST FOLLOWS THE DETERIORATING CIRCULATION UNTIL IT PASSES OVER JAPAN INTO THE PACIFIC OCEAN. FOR THE DURATION OF THE FORECAST, THE INTENSITY WILL INCREASE BRIEFLY TO 45 KNOTS AS THE SYSTEM TRACKS OVER WATER BEFORE WEAKENING BACK TO 40 KNOTS AFTER IT MAKES LANDFALL ON HONSHU. THE WIND FIELD WILL BECOME MORE EXPANSIVE AS THE SYSTEM COMPLETES ETT. NUMERICAL MODEL GUIDANCE IS IN OVERALL GOOD AGREEMENT WITH NAVGEM AND GFS AS THE PRINCIPLE OUTLIERS TO THE SOUTH OF THE CONSENSUS. HOWEVER, THE ALONG-TRACK SPEED IS ALREADY EXCEEDING THE FORECAST SPEED, WHICH COULD LEAD TO SIGNIFICANT ALONG TRACK ERRORS. DUE TO THE POTENTIAL FOR HIGH ALONG-TRACK ERRORS, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN