MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (KROSA) WARNING NR 027// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 11W (KROSA), LOCATED APPROXIMATELY 212 NM WEST OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A VERY EXPANSIVE SYSTEM SPANNING OVER 600NM WITH DEEP BUT WIDELY FRAGMENTED CONVECTIVE BANDS SPIRALING AROUND A LARGE, RAGGED AND FULLY EXPOSED LOW-LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE CENTER OF THE LLC. THE INITIAL INTENSITY OF 55KTS IS AVERAGED FROM AGENCY DVORAK ESTIMATES RANGING FROM T3.5/45KTS TO T4.0/65 KTS AND REFLECTS THE SUSTAINED CONVECTIVE SIGNATURE. UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH A LOW DIRECTLY OVER THE LLC THAT IS CAUSING SUBSIDENCE. HOWEVER, AROUND THE LOW IS A BROAD ANTICYCLONIC OUTFLOW THAT IS PROVIDING VENTILATION TO THE OUTER CONVECTIVE BANDS. ALONG-TRACK SST AT 30C REMAINS CONDUCIVE. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A BUILDING SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 48 HOURS, TS 11W WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STR. AFTERWARD, IT WILL TURN POLEWARD AND CREST THE STR AXIS, MAKING LANDFALL OVER EASTERN KYUSHU AROUND SHORTLY BEFORE TAU 72. THE MARGINAL CONDITIONS WILL SUSTAIN THE CURRENT INTENSITY AT BEST UP TO TAU 24. AFTERWARD, INCREASING POLEWARD OUTFLOW AHEAD OF A MID-LATITUDE TROUGH WILL PROMOTE INTENSIFICATION TO A PEAK OF 65 KNOTS BY TAU 48. NUMERICAL MODELS ARE IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST. C. AFTER TAU 72, LAND INTERACTION, INCREASING VWS, AND COOLER SSTS IN THE SEA OF JAPAN (SOJ) WILL COMBINE TO GRADUALLY WEAKEN THE SYSTEM DOWN TO 50KTS AS IT EXITS INTO THE SOJ THEN DOWN TO 30KTS BY TAU 120 AS IT LANDS OVER THE SAKHALIN ISLAND. CONCURRENTLY, BY TAU 96, TS KROSA WILL BEGIN EXTRA-TROPICAL TRANSITION AS IT ENTERS THE BAROCLINIC ZONE, BECOMING A COLD CORE LOW BY TAU 120. NUMERICAL MODELS SPREAD OUT TO OVER 600 NM BY TAU 120 WITH NAVGEM AND JGSM AS NOTABLE RIGHT OUTLIERS. THERE IS OVERALL MODERATE CONFIDENCE IN THE JTWC FORECAST TRACK THAT IS LAID JUST TO THE LEFT OF CONSENSUS TO OFFSET THE UNLIKELY NAVGEM/JGSM SOLUTION THAT DRIVES THE VORTEX INTO THE STR.// NNNN NNNN