MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (NAKRI) WARNING NR 01// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 12W (NAKRI), LOCATED APPROXIMATELY 214 NM SOUTH-SOUTHWEST OF KUNSAN AB, HAS TRACKED NORTH-NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A TIGHTLY-WRAPPED, EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTIVE BANDS WRAPPING BROADLY FROM THE SOUTHEAST QUADRANT INTO THE NORTH QUADRANT. DEEP CONVECTION HAS REMAINED DISPLACED OVER THE EASTERN SEMI-CIRCLE OF THE SYSTEM, HOWEVER, THE SURFACE WIND FIELD HAS CONTRACTED OVER THE PAST 24 HOURS AND THE CURRENT RADIUS OF MAXIMUM WINDS IS 90 TO 110 NM BASED ON A 020159Z ASCAT IMAGE. A 020438Z NOAA-19 IMAGE INDICATES TIGHTLY-WRAPPED SHALLOW BANDING WRAPPING INTO THE CENTER WITH FRAGMENTED DEEP CONVECTIVE BANDING. BASED ON THE MSI, THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION. THE CURRENT INTENSITY IS ASSESSED AT 40 KNOTS BASED ON THE ASCAT DATA AS WELL AS RECENT SHIP OBSERVATIONS NEAR THE SYSTEM. A 020437Z AMSU CROSS-SECTION SUPPORTS A WARM-CORE SYSTEM AND SHOWS A DEFINED WARM ANOMALY OF +2C. SEA SURFACE TEMPERATURE (SST) VALUES ARE MARGINALLY FAVORABLE AT 25 TO 26C. UPPER-LEVEL ANALYSIS INDICATES LOW TO MODERATE VERTICAL WIND SHEAR OVER THE SYSTEM OFFSET BY GOOD POLEWARD AND EQUATORWARD OUTFLOW. TS 12W IS TRACKING SLOWLY NORTHWARD ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND ESTABLISHES THE FORECAST PHILOSOPHY. B. TS NAKRI IS FORECAST TO CONTINUE TRACKING NORTHWARD ALONG THE NORTHWESTERN PERIPHERY OF THE STR THROUGH TAU 24, HOWEVER, THE SYSTEM IS EXPECTED TO ACCELERATE SHARPLY EAST-NORTHEASTWARD AS IT TRACKS POLEWARD OF THE STR AND INTO MIDLATITUDE WESTERLY FLOW. TS 12W IS FORECAST TO WEAKEN AFTER TAU 24 AS IT TRACKS OVER COOLER SST, BEGINS INTERACTING WITH LAND AND ENCOUNTERS INCREASING VERTICAL WIND SHEAR. TS 12W IS FORECAST TO MAKE LANDFALL NEAR TAU 48 AND WILL DISSIPATE QUICKLY AS IT TRACKS OVER THE ROUGH TERRAIN OF THE KOREAN PENINSULA WITH THE REMNANTS EMERGING OVER THE EAST SEA AFTER TAU 60. THE AVAILABLE DYNAMIC AIDS ARE IN GOOD AGREEMENT LENDING HIGH CONFIDENCE TO THE FORECAST TRACK.// NNNN NNNN