MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (HALONG) WARNING NR 09// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 11W (HALONG), LOCATED APPROXIMATELY 75 NM NORTHWEST OF NAVSTA GUAM, HAS TRACKED WESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH CURVED DEEP CONVECTIVE BANDING OVER THE SOUTHERN SEMI- CIRCLE. A 301001Z TRMM 37 GHZ IMAGE, HOWEVER, INDICATES A WELL- DEFINED LLCC WITH A SMALL MICROWAVE EYE. THIS IMAGE SHOWS STRONGER, DEEPER CONVECTIVE BANDING OVER THE SOUTHERN SEMI-CIRCLE, WHICH CORRESPONDS TO THE 300034Z ASCAT PARTIAL IMAGE SHOWING WEAKER WINDS OVER THE NORTHERN SEMI-CIRCLE AND NEAR GALE-FORCE WINDS OVER THE SOUTHERN SEMI-CIRCLE. OVER THE PAST 24 HOURS, THE TUTT HAS WEAKENED AND SHIFTED EAST ALLOWING INCREASING UPPER-LEVEL NORTHERLY FLOW TO AFFECT THE SYSTEM. RECENT ANIMATED WATER VAPOR IMAGERY CURRENTLY DEPICTS THIS NORTHERLY, CONVERGENT FLOW IMPINGING ON THE NORTHERN PERIPHERY OF THE SYSTEM, WHICH HAS LED TO THE RECENT WEAKENING TREND AND SHEARING OF DEEP CONVECTION SOUTHWARD. BASED ON THE TRMM IMAGE AND AND RECENT RADAR FIXES, THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION (30/12Z). THE INITIAL INTENSITY IS ASSESSED AT 50 KNOTS BASED ON AN AVERAGE OF DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 45 TO 55 KNOTS. TS 11W IS TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 11W IS EXPECTED TO TRACK WESTWARD TO WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 36. AFTER TAU 36, THE STR IS EXPECTED TO RE-ORIENT POLEWARD AS THE MONSOON DEPRESSION (INVEST 96W) TRACKS TOWARD WESTERN JAPAN AND THE SYSTEM SHOULD TURN NORTHWESTWARD. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 48 BUT DIVERGE AFTER TAU 48 WITH UKMO AND GFDN TRACKING THE SYSTEM WEST-NORTHWESTWARD. THE BULK OF THE GUIDANCE SUPPORTS THE NORTHWESTWARD TURN AND MAKES MORE METEOROLOGICAL SENSE WITH THE RESPECT TO HOW THE MONSOON DEPRESSION WILL INFLUENCE THE STEERING PATTERN. TS 11W IS FORECAST TO MAINTAIN INTENSITY THROUGH TAU 12 AS IT STRUGGLES WITH THE NORTHERLY VERTICAL WIND SHEAR (VWS) BUT SHOULD BEGIN TO SLOWLY INTENSIFY BY TAU 24 AS THE VWS RELAXES. C. TS HALONG IS EXPECTED TO TRACK SLOWLY NORTH-NORTHWESTWARD ALONG THE WESTERN PERIPHERY OF THE STR IN THE EXTENDED TAUS. WITH THE EXCEPTION OF GFDN AND UKMO, THE MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK. TS 11W IS FORECAST TO WEAKEN AS IT TRACKS INTO NORTHERLY UPPER-LEVEL FLOW AND INCREASING VWS ASSOCIATED WITH A BROAD UPPER-LEVEL HIGH TO THE NORTHWEST. DUE TO THE UNCERTAINTY IN THE TRACK SPEEDS AND INTENSITY FORECAST, THERE IS OVERALL LOW CONFIDENCE IN THE JTWC FORECAST.// NNNN NNNN