MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR 038// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 11W (KROSA), LOCATED APPROXIMATELY 118 NM SOUTH-SOUTHEAST OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS RAGGED CONVECTION ROTATING AROUND A BROAD LOW LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE AND IS BASED ON THE MSI LOOP AND A 150000Z HIMAWARI VISIBLE SATELLITE IMAGE. THE INITIAL INTENSITY OF 55 KNOTS IS BASED ON A DVORAK CURRENT INTENSITY (CI) ESTIMATE OF T3.5 (55 KNOTS) FROM PGTW WHICH IS SUPPORTED BY A 52 KNOT OBSERVATION AT CAPE MUROTO (90 NM NORTHEAST OF THE STORM CENTER). ENVIRONMENTAL ANALYSIS SHOWS FAVORABLE VERTICAL WIND SHEAR (5 TO 10 KNOTS). UPPER LEVEL OUTFLOW ALSO REMAINS FAVORABLE WITH GOOD POLEWARD AND EQUATORWARD OUTFLOW CHANNELS. SEA SURFACE TEMPERATURES ALSO REMAIN FAVORABLE, BETWEEN 28 AND 29 DEGREES CELSIUS. TS 11W IS TRACKING NORTHWARD WHILE POSITIONED ALONG THE WESTERN EDGE OF A SUBTROPICAL RIDGE (STR) WHICH IS LOCATED TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 11W WILL CONTINUE TO TRACK GENERALLY NORTHWARD OVER THE NEXT 12 HOURS. LAND INTERACTION AND COOLER SEA SURFACE TEMPERATURES WILL ALLOW TS 11W TO DECREASE TO 45 KNOTS IN INTENSITY AT TAU 12. AFTER TAU 12 AN APPROACHING WEST TO EAST MOVING SHORTWAVE TROUGH WILL HELP TO ACCELERATE TS 11W TO THE NORTHEAST. TS 11W WILL CONTINUE TO ENCOUNTER COOLER SEA SURFACE TEMPERATURES AS IT TRACKS NORTHEASTWARD IN THE SEA OF JAPAN. BY TAU 24, TS 11W WILL BEGIN INTERACTING WITH THE BAROCLINIC ZONE AND BEGIN EXTRA-TROPICAL TRANSITION (ETT). TS 11W WILL COMPLETE ETT BY TAU 48 AS IT TRACKS NORTHEASTWARD. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN