MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (FUNG-WONG) WARNING NR 06// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 16W (FUNG-WONG), LOCATED APPROXIMATELY 204 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 18 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS DEEP CONVECTIVE BANDING ACROSS THE WESTERN SEMI-CIRCLE OF A LOW LEVEL CIRCULATION CENTER (LLCC) THAT IS MOSTLY EXPOSED TO THE NORTH OF THE DEEPEST CONVECTION TO THE SOUTH. THE CURRENT POSITION IS BASED ON THE EIR LOOP WITH GOOD CONFIDENCE DUE TO THE EXPOSED NATURE OF THE LLCC. THE INITIAL INTENSITY REMAINS ASSESSED AT 35 KNOTS BASED ON PERSISTENCE FROM A PREVIOUS ASCAT PASS AND DVORAK INTENSITY ESTIMATES RANGING FROM 30 TO 35 KNOTS. UPPER- LEVEL ANALYSIS INDICATES A MARGINALLY CONDUCIVE ENVIRONMENT AS NORTHERLY VERTICAL WIND SHEAR (VWS) HAS INCREASED TO MODERATE LEVELS (10 TO 20 KNOTS) AND EQUATORWARD OUTFLOW REMAINS STRONG. TS FUNG- WONG IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) THAT IS POSITIONED TO THE NORTHEAST OF THE SYSTEM. 3. FORECAST REASONING. A. THE TRACK HAS BEEN SIGNIFICANTLY SLOWED IN THE EXTENDED PORTION OF THE FORECAST AS MODELS HAVE COME INTO A BETTER AGREEMENT REGARDING ESTABLISHMENT OF THE SUBTROPICAL RIDGE. B. THROUGHOUT THE NEXT 24 HOURS, TS 16W WILL CONTINUE TO TRACK TO THE NORTHWEST, AND THROUGH NORTHERN LUZON, UNDER THE INFLUENCE OF THE STR TO THE EAST. A RIDGE CURRENTLY OVER SOUTHEASTERN CHINA WILL RETROGRADE TO THE WEST AND WEAKEN, ALLOWING THE SYSTEM TO TRACK TO THE NORTH AS THE STR TO THE EAST REORIENTS. MODELS ARE IN GOOD AGREEMENT IN THE FORECAST TRACK THROUGH TAU 48. DUE TO LAND INTERACTION WITH NORTHERN LUZON AND THE EASTERN SPINE OF TAIWAN, THE INTENSITY OF FUNG-WONG IS NOT EXPECTED TO INCREASE SIGNIFICANTLY THROUGH THIS TIME. HOWEVER, BEYOND TAU 48, MODELS DEPICT THREE SCENARIOS. THE FIRST, AND LEAST LIKELY, SCENARIO HAS THE SYSTEM STRAIGHT-RUNNING TO THE NORTHWEST. THIS WOULD REQUIRE THE RIDGE OVER CHINA TO REBUILD AND EXTEND ACROSS TAIWAN INTO THE EAST CHINA SEA. BASED ON A 181200Z 500MB ANALYSIS, THE RIDGE HAS ALREADY BEGUN RETREATING, MAKING THIS SITUATION, FAVORED BY GFDN, VERY UNLIKELY. THE NAVGEM, HWRF AND GFS ENSEMBLE SOLUTION SHOW THE SYSTEM CONTINUING TO TRACK NORTHWARD THROUGH TAIWAN AND SLOWING DOWN SIGNIFICANTLY, TRACKING INTO THE WESTERN EAST CHINA SEA THROUGH TAU 72. THE MAIN STEERING INFLUENCE IN THIS SCENARIO IS THE REBUILDING AND REORIENTING STR TO THE EAST, WHICH WOULD BECOME ELONGATED NORTH TO SOUTH. WHILE THE JENS, JGSM AND GFS SOLUTIONS ARE SIMILAR, THEY CARRY TS 16W TO THE NORTHEAST BEYOND TAU 48 AND RECURVE THE SYSTEM AROUND THE RIDGE AXIS OF THE STR, WHICH IS NOT PREDICTED TO EXTEND AS FAR NORTH-SOUTH. ALL SOLUTIONS TAKE FUNG-WONG FARTHER WEST OF THE RYUKYU ISLANDS THAN THE PREVIOUS FORECAST. DUE TO THIS TRIFURCATION IN THE FORECAST, THERE IS LOW CONFIDENCE IN THE FORECAST TRACK BEYOND TAU 48. C. IN THE EXTENDED TAUS, MODELS DEPICT THREE SEPARATE SCENARIOS AS MENTIONED ABOVE, WITH THE WESTERN SCENARIO RUNNING THE SYSTEM INTO CHINA, THE NORTHERN OFF THE COAST OF SHANGHAI AND THE FINAL POSSIBILITY OF A RECURVE TAKING THE SYSTEM JUST SHORT OF THE KYUSHU COAST. THE MAJOR FACTOR IN THE EXTENDED TAUS IS THE LOCATION OF THE UPPER LEVEL JET AND THE STR TO THE EAST. MODELS AGREE ON A SLIGHT BREAK IN THE PERSISTENT JET FEATURE AROUND TAU 120. WITH REGARD TO THE STR, THE NAVGEM SOLUTION HAS 16W TRACKING TO THE NORTH AND BECOMING QUASI-STATIONARY UNDER A WEAK STEERING ENVIRONMENT. IN CONTRAST, THE JAPANESE MODELS DEPICT FUNG-WONG TURNING AROUND A WEAKER STR INTO THE WESTERLIES AROUND TAU 96 AND STARTING TO BECOME EMBEDDED IN THE BAROCLINIC ZONE BY THE END OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS SPLIT BETWEEN THESE TWO MODEL SCENARIOS, SLOWING THE TRACK SPEED OF THE SYSTEM IN THE LATER TAUS SIGNIFICANTLY, BUT CONTINUING THE TREND OF THE SYSTEM TURNING TO THE NORTHWEST UNDER THE WESTERLIES AND NORTH OF THE STR TO THE EAST. DUE TO THE SIGNIFICANT DIFFERENCES IN THE SPEED OF THE TRACK IN THE EXTENDED TAUS, THERE IS OVERALL LOW CONFIDENCE IN THE FORECAST.// NNNN NNNN