WDPN31 PGTW 122100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 04W (SINLAKU) WARNING NR 016// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 11.6N 149.5E INITIAL INTENSITY: 155 KTS GEOGRAPHIC REFERENCE: 307 NM EAST-SOUTHEAST OF NAVSTA GUAM MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 40 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS SUPER TYPHOON (STY) 04W (SINLAKU) WITH A CLEAR AND WELL-DEFINED EYE FEATURE, CHARACTERIZED BY A WARM (19-21 C) AND SYMMETRIC STRUCTURE. IMMEDIATELY OUTSIDE OF THE EYEWALL, A UNIFORM AND PERSISTENT CENTRAL DENSE OVERCAST HAS CONTINUED TO ILLUSTRATE INTENSIFICATION IN THE HIGHLY FAVORABLE ENVIRONMENT. ALOFT, ROBUST RADIAL OUTFLOW HAS REMAINED, IDENTIFIED BY OUTWARDLY BURSTING CIRRIFORM STRIATIONS AWAY FROM STY 04W, WITH VISIBLE TRANSVERSE BANDING EXTENDING THROUGHOUT THE SYSTEMS SOUTHERN SEMICIRCLE ON ANIMATED ENHANCED WATER VAPOR IMAGERY. THE ENVIRONMENTAL ANALYSIS HAS REVEALED A HIGHLY FAVORABLE ENVIRONMENT, WITH WARM SEA SURFACE TEMPERATURES OF 27-28 C, LOW VERTICAL WIND SHEAR (VWS) OF LESS THAN 05 KTS, SUPPORTIVE UPPER-LEVEL OUTFLOW, AND A DEEPLY MOIST PROFILE. THE INITIAL POSITION HAS BEEN PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED AND PRESENT EYE-FEATURE OBSERVED ON ANIMATED SHORTWAVE INFRARED SATELLITE IMAGERY. THE INITIAL INTENSITY HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE AT 155 KTS, DERIVED FROM SUBJECTIVE AGENCY DVORAK ESTIMATES ALIGNED AT T7.5, AND CIMSS OBJECTIVE INTENSITY ESTIMATES RANGING FROM 151-165 KTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: COMPETING STEERING ENVIRONMENT, WITH AN EXTENSION OF A NEAR-EQUATORIAL RIDGE (NER) POSITIONED DIRECTLY TO THE EAST AND A DEEP-LAYER SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHWEST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.5 - 155 KTS RJTD: T7.5 - 155 KTS RCTP: T7.5 - 155 KTS KNES: T7.5 - 155 KTS CIMSS SATCON: 151 KTS AT 121547Z CIMSS ADT: 164 KTS AT 121730Z CIMSS AIDT: 160 KTS AT 121730Z CIMSS D-MINT: 165 KTS AT 121812Z CIMSS D-PRINT: 161 KTS AT 121800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 0-5 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: THE FORECAST TRACK FOR STY 04W HAS NOT CHANGED SIGNIFICANTLY SINCE THE PREVIOUS FORECAST CYCLE, WITH A NORTHWEST TRACK FORECASTED THROUGH THE NEXT 48 HOURS. THE ISLAND OF SAIPAN HAS REMAINED IN VERY CLOSE PROXIMITY TO THE EXPECTED TRACK, WITH THE TAU 36 POSITION PLACED JUST SOUTH-SOUTHEAST OF TINIAN. WITH THAT BEING SAID, STY 04W IS EXPECTED TO CONTINUE NORTHWESTWARD THROUGH TAU 48, ALONG THE WESTERN PERIPHERY OF AN EXTENSION OF THE NER POSITIONED DIRECTLY TO THE EAST. FOLLOWING TAU 48, THE NER TO THE EAST IS FORECASTED TO BEGIN RETREATING EASTWARD NEAR THE SAME PERIOD THE STR TO THE WEST WEAKENS WESTWARD. AT THIS TIME, THE TRACK FOR STY SINLAKU BECOMES NORTHWARD AND THEN NORTH-NORTHEASTWARD BETWEEN TAU 48 AND TAU 72 AS THE SYSTEM ROUNDS THE RIDGE AXIS. FOLLOWING TAU 72, THE TRACK FOR STY 04W IS FORECASTED TO BECOME NORTH-NORTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD, AND PROGRESS ALONG THE NORTHWEST EXTENT OF THE NER POSITIONED TO THE SOUTHEAST. REGARDING INTENSITY, STY 04W IS ASSESSED TO CURRENTLY BE UNDERGOING AN EYEWALL REPLACE CYCLE, AND IS FORECASTED TO BEGIN THE INITIAL WEAKENING PHASE IN THE NEAR FUTURE AS DRY AIR ALSO BEGINS SLOWLY WRAPPING INTO THE SYSTEMS OUTERMOST PERIPHERY WHILE UPPER- LEVEL DIVERGENCE SLOWS. STY 04W IS EXPECTED TO GRADUALLY WEAKEN AS THE SYSTEM NEARS THE MARIANAS, WITH INTENSITIES NEAR 140 KTS EAST OF GUAM AT TAU 24 AND THEN 125 KTS JUST SOUTH-SOUTHEAST OF SAIPAN NEAR TAU 36. FOLLOWING TAU 36, CONTINUED WEAKENING OF SURFACE INTENSITIES ARE FORECASTED AS SINLAKU ROUNDS THE STR AXIS AT TAU 72 WHILE DRY AIR CONTINUES TO BATTER THE SYSTEMS OUTER PERIPHERY. AFTER TAU 72, DRY AIR WILL PERSIST AND BEGIN ERODING SINLAKUS HORIZONTAL PROFILE WHILE SEA SURFACE TEMPERATURES COOL TO NEAR 26 C, FURTHER WEAKENING SURFACE INTENSITIES TOWARD 75 KTS BY TAU 120. MODEL DISCUSSION: NUMERICAL MODEL PREDICTION GUIDANCE REMAINS IN FAIR AGREEMENT, WITH A CROSS-TRACK SPREAD OF NEAR 83 NM BY TAU 24 AS THE SYSTEM NEARS THE MARIANAS. BY TAU 36, THE CROSS-TRACK SPREAD OF JTWC CONSENSUS MEMBERS INCREASES TO 131 NM DURING THE SYSTEMS EXPECTED TRACK NEAR SAIPAN. FOLLOWING TAU 36, THE NUMERICAL WEATHER PREDICTION AND ARTIFICIAL INTELLIGENCE (AI) CROSS-TRACK GUIDANCE BEGINS TO GROW SIGNIFICANTLY, ILLUSTRATING A 317 NM SPREAD BY TAU 72 AND 577 NM DIVERGENCE BY THE END OF THE FORECAST PERIOD. EXCLUDING THE SINGLE OUTLIER, NAVGEM, THE SPREAD ENVELOPE IS MUCH MORE ALIGNED, LENDING MEDIUM TRACK CONFIDENCE UNTIL TAU 72, AND LOW THEREAFTER. REGARDING INTENSITY, ALL JTWC INTENSITY CONSENSUS MEMBERS CHARACTERIZE A SLOW AND GRADUAL WEAKENING PHASE THROUGH THE ENTIRETY OF THE FORECAST PERIOD, WITH THE EXCEPTION OF GFS, WHICH ILLUSTRATES A SHARP WEAKENING PHASE IN THE NEAR-TERM. THE OFFICIAL JTWC INTENSITY FORECAST HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE THROUGHOUT THE 120 HOUR PERIOD, AND PLACED SLIGHTLY HIGHER THAN THE MULTI-MODEL CONSENSUS, CLOSER TO THE HAFS INTENSITY SOLUTION. THE RI SIGNAL HAS CONTINUED TO DECREASE SINCE THE PREVIOUS WARNING, WITH COAMPS-TC EPS INTENSITY PROBABILITIES SHOWING AN EXPECTED STEADY TO MODERATE WEAKENING INTENSITY FORECAST THROUGH 120 HOUR PERIOD. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN