Typhoon 14W(MUIFA) slowly approaching China//TS 15W(MERBOK): to peak at CAT 2 by 72h//Invest 92W: TCFA// 1209utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 14W(MUIFA) AND 15W(MERBOK). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON INVEST 92W.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM-SIZED TYPHOON WITH A SYMMETRICAL DEEP CENTRAL CONVECTION THAT HAS JUST COMPLETED AN EYEWALL REPLACEMENT CYCLE AS EVIDENCED BY AN EYE THAT HAS SHRUNK DOWN TO 18NM IN DIAMETER FROM 60NM 6HRS PRIOR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN THE MSI LOOP THAT WAS CONCENTRIC WITH A WELL-DEFINED CIRCULATION FEATURE IN THE COMPOSITE RADAR LOOP FROM JMA. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON EQUIVALENT AGENCY DVORAK ESTIMATES AND REFLECTS THE SLIGHT 6-HR DEGRADATION. ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MEDIUM RADIAL OUTFLOW AND LIGHT VWS OFFSET BY COOLING SST DUE TO UPWELLING BROUGHT ON BY THE CURRENT SLOW STORM MOTION.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: A MIDLATITUDE SHORTWAVE TROUGH EXITING CHINA VIA THE YELLOW SEA HAS WEAKENED THE STEERING STR AND ALLOWED THE SYSTEM TO TRACK MORE NORTHWARD. BEHIND THE TROUGH, A SECONDARY STR TO THE NORTHWEST IS COMPETING FOR STEERING CAUSING THE SLOW STORM MOTION. AFTER TAU 24, THE STR TO THE NORTHEAST WILL BUILD ANEW AND REGAIN FULL STEERING AND ACCELERATE TY 14W NORTH-NORTHWESTWARD. THE MARGINAL ENVIRONMENT WILL VERY SLOWLY WEAKEN THE SYSTEM DOWN TO 70KTS BY TAU 48. AFTERWARD, COOLING SST IN THE EAST CHINA SEA, INCREASING VWS, AND LANDFALL INTO NORTHEAST CHINA VIA SHANGHAI WILL RAPIDLY ERODE THE SYSTEM AND BY TAU 120 WILL DISSIPATE OVER THE SHANDONG BANDAO PENINSULA.

MODEL DISCUSSION: THE MAIN PACK OF NUMERICAL MODELS ARE IN TIGHT AGREEMENT EVENLY SPREADING OUT TO 135NM BY TAU 72 THEN TO 400NM+ BY TAU 120 AS THE MODELS LOSE A DISSIPATING VORTEX. NVGM AND JGSM ARE THE LEFT OUTLIERS OUTSIDE THE MAIN PACK. IN VIEW OF THIS, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS, LAID CLOSE TO THE MODEL TRACK AND INTENSITY CONSENSUS, UP TO TAU 72 THEN LOW CONFIDENCE AFTERWARD.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MEDIUM-SIZED TYPHOON WITH A SYMMETRICAL DEEP CENTRAL CONVECTION THAT HAS JUST COMPLETED AN EYEWALL REPLACEMENT CYCLE AS EVIDENCED BY AN EYE THAT HAS SHRUNK DOWN TO 18NM IN DIAMETER FROM 60NM 6HRS PRIOR. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN THE MSI LOOP THAT WAS CONCENTRIC WITH A WELL-DEFINED CIRCULATION FEATURE IN THE COMPOSITE RADAR LOOP FROM JMA. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON EQUIVALENT AGENCY DVORAK ESTIMATES AND REFLECTS THE SLIGHT 6-HR DEGRADATION. ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH MEDIUM RADIAL OUTFLOW AND LIGHT VWS OFFSET BY COOLING SST DUE TO UPWELLING BROUGHT ON BY THE CURRENT SLOW STORM MOTION.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: A MIDLATITUDE SHORTWAVE TROUGH EXITING CHINA VIA THE YELLOW SEA HAS WEAKENED THE STEERING STR AND ALLOWED THE SYSTEM TO TRACK MORE NORTHWARD. BEHIND THE TROUGH, A SECONDARY STR TO THE NORTHWEST IS COMPETING FOR STEERING CAUSING THE SLOW STORM MOTION. AFTER TAU 24, THE STR TO THE NORTHEAST WILL BUILD ANEW AND REGAIN FULL STEERING AND ACCELERATE TY 14W NORTH-NORTHWESTWARD. THE MARGINAL ENVIRONMENT WILL VERY SLOWLY WEAKEN THE SYSTEM DOWN TO 70KTS BY TAU 48. AFTERWARD, COOLING SST IN THE EAST CHINA SEA, INCREASING VWS, AND LANDFALL INTO NORTHEAST CHINA VIA SHANGHAI WILL RAPIDLY ERODE THE SYSTEM AND BY TAU 120 WILL DISSIPATE OVER THE SHANDONG BANDAO PENINSULA.

MODEL DISCUSSION: THE MAIN PACK OF NUMERICAL MODELS ARE IN TIGHT AGREEMENT EVENLY SPREADING OUT TO 135NM BY TAU 72 THEN TO 400NM+ BY TAU 120 AS THE MODELS LOSE A DISSIPATING VORTEX. NVGM AND JGSM ARE THE LEFT OUTLIERS OUTSIDE THE MAIN PACK. IN VIEW OF THIS, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS, LAID CLOSE TO THE MODEL TRACK AND INTENSITY CONSENSUS, UP TO TAU 72 THEN LOW CONFIDENCE AFTERWARD.

THE AREA OF CONVECTION (INVEST 92W) PREVIOUSLY LOCATED NEAR 26.8N 143.4E IS NOW LOCATED NEAR 22.9N 139.1E, APPROXIMATELY 165 NM SOUTHWEST OF IWO TO. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A BROAD LOW LEVEL CIRCULATION (LLC) WITH CONVECTIVE BANDING IN THE SOUTHWESTERN PERIPHERY OF THE LLC. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT. THE SYSTEM SITS BELOW A WEAK UPPER LEVEL LOW WITH LIMITED EQUATORWARD OUTFLOW, LOW (5-10 KNOTS) VERTICAL WIND SHEAR AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE IN RELATIVE AGREEMENT THAT INVEST 92W WILL REMAIN GENERALLY QUASI- STATIONARY OVER THE NEXT 24-36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH.

GLOBAL MODELS ARE IN RELATIVE AGREEMENT THAT INVEST 92W WILL REMAIN GENERALLY QUASI- STATIONARY OVER THE NEXT 24-36 HOURS.