MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (MITAG) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 19W (MITAG), LOCATED APPROXIMATELY 156 NM SOUTH- SOUTHEAST OF SHANGHAI, CHINA, HAS TRACKED NORTHWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A FULLY-EXPOSED, RAGGED, BUT WELL-DEFINED LOW-LEVEL CIRCULATION DE-COUPLED FROM THE DEEP CONVECTION TO THE NORTH. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI AND ON A COMPOSITE RADAR LOOP FROM CMA. THE INITIAL INTENSITY OF 65 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES AND NEARBY SURFACE OBSERVATIONS AND REFLECTS THE WEAKENING. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY INDICATES RAPIDLY DECAYING DEEP CONVECTION SHEARING NORTHWARD DUE TO MODERATE TO STRONG (20-30 KNOTS) SOUTHERLY VERTICAL WIND SHEAR (VWS). SST VALUES HAVE ALSO DECREASED TO 25-26C. TY 19W IS TRACKING ALONG THE WESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 19W IS FORECAST TO GRADUALLY TURN NORTH-NORTHEASTWARD TO NORTHEASTWARD AS IT ROUNDS THE STR AXIS, MAKING LANDFALL AROUND TAU 30 SOUTH OF KUNSAN, SOUTH KOREA. BY TAU 48, IT WILL EXIT INTO THE SEA OF JAPAN (SOJ) AND BEGIN EXTRA-TROPICAL TRANSITION (ETT) AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE. THE SYSTEM SHOULD WEAKEN RAPIDLY DUE TO INCREASING VWS, COOLER SST AND INTERACTION WITH LAND. TY MITAG WILL COMPLETE ETT BY TAU 72 IN THE SOJ AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN STRONG MIDLATITUDE WESTERLY FLOW. SST VALUES WILL DECREASE TO LESS THAN 24C, WHICH WILL FURTHER AID IN WEAKENING THE SYSTEM. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH MINIMAL SPREAD IN SOLUTIONS, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK THROUGH TAU 72. C. AFTER TAU 72, THIS COLD-CORE EXTRA-TROPICAL LOW WILL ACCELERATE EAST-NORTHEASTWARD OVER NORTHERN HONSHU. THE SYSTEM IS STILL EXPECTED TO MAINTAIN GALE-FORCE WINDS. DUE TO THE BROAD NATURE OF THIS LOW AND THE LARGE SPREAD IN THE NUMERICAL MODELS, THERE IS LOW CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK.// NNNN NNNN