WDPN32 PGTW 010300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (DAMREY) WARNING NR 14// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 11W (DAMREY), LOCATED APPROXIMATELY 240 NM SOUTHEAST OF SASEBO, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT 20 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE FAST MOVING, WELL-DEFINED, LOW LEVEL CIRCULATION CENTER (LLCC) HAS BEEN MAINTAINING A STEADY TRACK TOWARDS SOUTHERN KYUSHU FOR THE PAST 12 HOURS. DEEP CONVECTION HAS NOW COMPLETELY WRAPPED AROUND THE LLCC ALONG THE NORTHERN PERIPHERY. RADAR IMAGERY FROM KYUSHU CLEARLY SHOWS THE LLCC AND ASSOCIATED RAIN BANDS. THE CURRENT INTENSITY OF 60 KNOTS IS BASED ON THE RECENT INCREASE IN DVORAK ESTIMATES FROM PGTW WHICH IS NOW IN LINE WITH THE DVORAK ESTIMATE FROM RJTD. UPPER LEVEL ANALYSIS INDICATES THE POLEWARD OUTFLOW CHANNEL REMAINS THE PRIMARY VENTING MECHANISM AND IS SUPPORTING THE SLOW INTENSIFICATION OBSERVED IN THE PAST 12 HOURS. DRY AIR CONTINUES TO WRAP ALONG THE SOUTHERN PERIPHERY, BUT IS SLOWLY WEAKENING AS OBSERVED IN ANIMATED WATER VAPOR IMAGERY AND MSI. TS 11W IS CURRENTLY STEERING ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING. B. TS 11W IS FORECAST TO STAY ON A STEADY TRACK TOWARD MAINLAND CHINA, TRACKING WESTWARD UNDER THE INFLUENCE OF THE STR TO THE NORTH. A SLOW INTENSIFICATION OVER THE NEXT 24 HOURS WILL BRING THE SYSTEM TO TYPHOON STRENGTH AS IT MOVES OVER VERY WARM SEA SURFACE TEMPERATURES ASSOCIATED WITH THE KUROSHIO CURRENT AND AN IMPROVING POLEWARD OUTFLOW CHANNEL. THIS INTENSIFICATION WILL BE SHORT-LIVED AS THE SYSTEM IS EXPECTED TO MAKE LANDFALL SHORTLY BEFORE TAU 36. THE UPPER LEVEL ENVIRONMENT REMAINS THE LIMITING FACTOR TO A GREATER DEVELOPMENTAL POTENTIAL. ONE CONCERN IS THE IMPACT OUTFLOW FROM TY 10W IS PLAYING ON THE EQUATORWARD OUTFLOW OF TS 11W AND THE VERTICAL WIND SHEAR. AS THE TWO SYSTEMS APPROACH ONE ANOTHER THE POSSIBILITY EXISTS FOR THE POLEWARD OUTFLOW FROM TY 10W TO IMPACT THE WESTERN HALF OF TS 11W, STIFLING OUTFLOW AND INCREASING VERTICAL WIND SHEAR. MODEL GUIDANCE HAS STARTED TO TIGHTEN IN THE LATER TAUS, WITH JGSM BEING THE NORTHERN OUTLIER, ALTHOUGH IT TOO HAS COME SOUTHWARD OVER THE PAST SIX HOURS. THE OFFICIAL JTWC TRACK FORECAST IS BASED ON THE MODEL CONSENSUS WITH HIGH CONFIDENCE.// NNNN