MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR 037// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (KROSA), LOCATED APPROXIMATELY 183 NM SOUTH OF IWAKUNI, JAPAN, HAS TRACKED NORTHWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN EXTENSIVE SYSTEM WITH A RAGGED LOW LEVEL CENTER SURROUNDED BY POCKETS OF DEEP CONVECTION DISPLACED 50 TO 100 NM AWAY. THE INITIAL POSITION IS BASED ON MULTI-AGENCY FIXES (INCLUDING RADAR) WITH GOOD CONFIDENCE, AND SUPPORTED BY A 141715Z NPP PASS. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS AFTER RECENT 08-12Z SCATTEROMETRY AND SMAP DATA INDICATED 50-PLUS KNOT WINDS WERE PRESENT IN THE NORTHEAST QUADRANT AT THAT TIME. THESE PEAK WINDS WERE DISPLACED 100 NM FROM THE CENTER, BUT CLEARLY ASSOCIATED WITH THE BROAD CONVECTIVE FLOW. THEREFORE, THE 18Z INTENSITY ESTIMATE IS MAINTAINING THE REVISED 12Z WIND ESTIMATE AND NOT INDICATIVE OF ACTUAL INTENSIFICATION. DVORAK CURRENT INTENSITY ESTIMATES RANGE FROM T3.0-T3.5 (45 TO 55 KNOTS) AND SATCON IS CURRENTLY AT 55 KNOTS. AN EXTENSIVE AREA OF GALES SURROUNDS THE SYSTEM, HOWEVER, AGAIN THE PEAK WINDS ARE ISOLATED AND DISPLACED WELL TO THE NORTHEAST OF THE CENTER. UPPER LEVEL OUTFLOW HAS CONTINUED TO IMPROVE AHEAD OF AN APPROACHING MIDLATITUDE TROUGH TO ITS WEST, AND THE EQUATORWARD OUTFLOW CHANNEL REMAINS EXCELLENT. SEA SURFACE TEMPERATURES (SST) REMAIN CONDUCIVE (28-29 DEGREES CELSIUS). THE CYCLONE IS TRACKING NORTHWARD ALONG THE WESTERN PERIPHERY OF AN EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 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 11W WILL CONTINUE ON ITS CURRENT TRACK AS IT ROUNDS THE WESTERN PERIPHERY OF THE AFOREMENTIONED STR. FORECAST PEAK WINDS AT LANDFALL WERE INCREASED DUE TO THE ADJUSTMENT TO THE INITIAL INTENSITY, HOWEVER, PEAK WINDS ARE EXPECTED TO REMAIN ISOLATED WELL AWAY FROM THE CENTER, AND OVER-LAND INTENSITIES SHOULD BE WEAKER DUE TO TERRAIN AND FRICTIONAL EFFECTS. BEYOND TAU 12, A MIDLATITUDE TROUGH WILL APPROACH FROM THE WEST, ERODING THE STR AND ALLOWING TS 11W TO RECURVE POLEWARD AROUND THE STR AXIS. AFTER RE-EMERGING INTO THE SEA OF JAPAN, GRADUAL WEAKENING IS FORECAST AS SST DECLINES TO THE NORTH, AND VERTICAL WIND SHEAR INCREASES DUE TO THE APPROACHING TROUGH. EXTRA-TROPICAL TRANSITION IS EXPECTED TO BEGIN BY TAU 36, AND GUIDANCE INDICATES THIS TRANSITION WILL BE COMPLETE BY TAU 48 AS KROSA WILL BE UNDERNEATH THE 200 MB MID-LATITUDE BAROCLINIC FLOW. DYNAMICAL MODELS ARE IN EXCELLENT AGREEMENT ON TRACK THROUGH TAU 48. THE JTWC FORECAST TRACK IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS AND PRIOR FORECAST WITH HIGH CONFIDENCE. // NNNN NNNN