WDPN31 PGTW 051500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15E (NOLO) WARNING NR 060// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.6N 176.2E INITIAL INTENSITY: 105 KTS GEOGRAPHIC REFERENCE: 961 NM NORTHWEST OF JOHNSTON ISLAND MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 45 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON (TY) 15E (NOLO) WITH A LARGE, SYMMETRICAL EYE MEASURING APPROXIMATELY 35NM IN DIAMETER. ADDITIONALLY, CLOUD TOPS ARE WARMING SLIGHTLY, PARTICULARLY ALONG THE WESTERN FLANK WHERE DRY AIR IS ENTRAINING INTO THE CORE. THE 050855Z ASCAT DATA REVEALS AN ASYMMETRIC WIND FIELD, WITH A THIN BAND OF STORM- AND TYPHOON-FORCE WINDS ALONG THE SOUTHWESTERN SEMICIRCLE CONTRASTED WITH AN EXPANSIVE RANGE OF ELEVATED WINDS WITHIN THE NORTHEAST SEMICIRCLE. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS), WARM (28-29 C) SEA SURFACE TEMPERATURES (SST), AND MODERATE POLEWARD OUTFLOW, OFFSET BY DRY AIR ENTRAINMENT FROM THE WEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE SYMMETRICAL CENTRAL EYE. THE INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AGENCY DVORAK FIXES. INITIAL WIND RADII BASIS: 050855Z ASCAT DATA CURRENT STEERING MECHANISM: THE SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHWEST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.5 - 102 KTS RCTP: T5.0 - 90 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD OTHER FACTORS: DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 15E IS FORECAST TO CONTINUE TRACKING GENERALLY WEST-NORTHWESTWARD TO WESTWARD WHILE IT REMAINS ON THE SOUTHERN PERIPHERY OF THE STEERING STR. BEGINNING AROUND TAU 96, 15E WILL BEGIN TO ROUND THE PERIPHERY OF THE RIDGE AND TURN POLEWARD INTO A BREAK BETWEEN THE STEERING RIDGE AND A BUILDING LOW- TO MID-LAYER RIDGE CENTERED OVER JAPAN. 15E WILL TRACK POLEWARD THROUGH TAU 120. REGARDING INTENSITY, 15E IS FORECAST TO GRADUALLY WEAKEN OVER THE NEXT 72 HOURS AS THE ENVIRONMENT GETS PROGRESSIVELY MORE UNFAVORABLE, WITH DECREASING OUTFLOW, INCREASING VWS, AND INCREASING DRY AIR ENTRAINMENT THROUGH TAU 72. AROUND TAU 72-96, THE VWS IS EXPECTED TO ABATE SLIGHTLY AND THE OUTFLOW IS EXPECTED TO MARGINALLY IMPROVE, ALLOWING 15E TO BRIEFLY REINTENSIFY THROUGH TAU 120. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72, WITH MINIMAL ALONG-TRACK OR CROSS-TRACK DEVIATION. AFTER TAU 72, HOWEVER, MODEL GUIDANCE STRUGGLES TO INTERPRET THE RECURVE AROUND THE STEERING RIDGE. THERE IS A SLIGHT BIFURCATION AFTER ABOUT TAU 60; THE GSM, COAMPS-TC, EXPERIMENTAL GOOGLE DEEPMIND, AND EXPERIMENTAL AI ECENS MEAN DEPICT A MUCH SHARPER POLEWARD TURN AND SUBSEQUENT NORTHEASTWARD TRACK. MEANWHILE, GFS, ECMWF, UKMET, NAVGEM, AND A HANDFUL OF AI-MODELS GENERALLY SHOW 15E TRACKING FARTHER WEST WITH A GRADUAL POLEWARD RECURVE. THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE FROM TAU 0-72. AFTER TAU 72, THE JTWC TRACK FORECAST IS PLACED WITH LOW CONFIDENCE, AND LIES CLOSE TO THE MULTI-MODEL CONSENSUS IN CONCURRENCE WITH THE BULK OF TRACK GUIDANCE. RELIABLE INTENSITY AIDS ARE IN AGREEMENT ON GENERAL INTENSITY TRENDS, BUT NOT EXACT INTENSITY. ALL MODELS DEPICT A STEADY WEAKENING TREND THROUGH TAU 72 FOLLOWED BY A SLIGHT REINTENSIFICATION. THE JTWC INTENSITY FORECAST IS IN CLOSE AGREEMENT WITH THE MULTI-MODEL CONSENSUS WITH OVERALL LOW CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 00-72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN