MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 19W (MITAG), 182 NM SOUTH-SOUTHWEST OF KUNSAN AB, SOUTH KOREA, HAS TRACKED NORTH-NORTHEASTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A SEMI-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 LOOP. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES AND CONSISTENT WITH A RECENT ASCAT DIRECT PASS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF STRONG (GREATER THAN 30KTS) SOUTHERLY VERTICAL WIND SHEAR (VWS). SST VALUES AT 25-26C ARE ALSO NON-CONDUCIVE. TS 19W IS TRACKING ALONG THE NORTHWESTERN 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. TS 19W IS FORECAST TO ACCELERATE NORTHEASTWARD TO EAST-NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR AXIS, MAKING LANDFALL JUST AFTER TAU 06 SOUTH OF KUNSAN. AFTER TAU 18, 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, CROSSING THE SOJ AND NORTHERN HONSHU, INTO THE PACIFIC OCEAN JUST SOUTH OF THE KURIL ISLANDS BY TAU 72. THE SYSTEM SHOULD CONTINUE TO WEAKEN DUE TO THE STRONG VWS, LAND INTERACTION AND COOLER SST, DROPPING TO 40KTS BY TAU 12 OVER THE RUGGED TERRAIN OF SOUTH KOREA. HOWEVER, BY TAU 24, DURING ETT IN THE SOJ, IT WILL SLIGHTLY INTENSIFY AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED IN THE BAROCLINIC ZONE WITH AN EXPANDED WIND FIELD. BY TAU 48, THE SYSTEM WILL TRANSFORM INTO A GALE-FORCE COLD CORE LOW. INTERACTION WITH NORTHERN HONSHU WILL DEGRADE THE CYCLONE DOWN TO 35KTS, POSSIBLY WEAKER, BY TAU 72, AS IT BECOMES MORE DIFFICULT TO DIFFERENTIATE ITS BROAD WIND FIELD FROM THE MIDLATITUDE BAROCLINIC FLOW. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH MINIMAL SPREAD IN SOLUTIONS UP TO TAU 48, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK THROUGH TAU 48, THEN LOW CONFIDENCE AFTERWARD.// NNNN NNNN