WDPN31 PGTW 260900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (SURIGAE) WARNING NR 013// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.9N 126.8E INITIAL INTENSITY: 70 KTS GEOGRAPHIC REFERENCE: 223 NM SOUTH-SOUTHWEST OF KADENA AB MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAPIDLY ORGANIZING SYSTEM POSITIONED FAVORABLY FOR NEAR-TERM RAPID INTENSIFICATION (RI). DEEP CONVECTION, FEATURING CONVECTIVE BURSTING AND VORTICAL HOT TOWERS (VHTS), INITIATED IN THE NORTHWEST QUADRANT APPROXIMATELY SIX HOURS AGO AND HAS CONTINUED TO SLOWLY WRAP AROUND INTO THE SOUTHERN SEMICIRCLE OF THE ASSESSED LOW-LEVEL CIRCULATION CENTER. A 260522Z ATMS 89GHZ MICROWAVE PASS REVEALS STRONG CONVECTION REMAINS FOCUSED ON THE WESTERN FLANK OF THE EYE FEATURE, WITH SECONDARY CURVED BANDING DEVELOPING IN THE SOUTHEASTERN QUADRANT. EARLIER MICROWAVE IMAGERY FROM 260000Z INDICATED THAT THE VORTEX HAD ALREADY ACHIEVED VERTICAL ALIGNMENT, THOUGH MSI SUGGESTS RESIDUAL MODERATE MID-LEVEL SOUTHEASTERLY SHEAR CONTINUES TO EXERT MINOR PRESSURE ON THE CORE. THE SYSTEM IS SITUATED WITHIN A COL REGION AT THE SUBTROPICAL RIDGE (STR) AXIS, FACILITATING ROBUST DUAL-CHANNEL OUTFLOW ALOFT AS EVIDENCED BY ANIMATED WATER VAPOR IMAGERY. THE CENTER OF 25W IS LOCATED ALONG THE SOUTHERN RANGE LIMIT OF THE JMA OKINAWA RADAR FEED; NONETHELESS, BASE REFLECTIVITY SUFFICIENTLY RESOLVES THE WESTERN EYEWALL ARC AND THE SOUTHWESTERN EYE BOUNDARY. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE CONCURRENT ATMS AND RADAR FIXES. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BIASED HIGHER THAN THE BULK OF SUBJECTIVE AND OBJECTIVE ESTIMATES NOTED BELOW IN DEFERENCE TO RECENT SYNTHETIC APERTURE RADAR (SAR) DATA AND OBSERVED RAPID CONVECTIVE CONSOLIDATION. ENVIRONMENTAL CONDITIONS ARE HIGHLY FAVORABLE, CHARACTERIZED BY VERY WARM SSTS (29-30C), STRONG DUAL-CHANNEL OUTFLOW ALOFT, AND LOW DEEP-LAYER VERTICAL WIND SHEAR (VWS). INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA. CURRENT STEERING MECHANISM: SYSTEM IS APPROACHING THE AXIS OF THE SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T3.0 - 45 KTS CIMSS SATCON: 53 KTS AT 260521Z CIMSS ADT: 51 KTS AT 260540Z CIMSS AIDT: 45 KTS AT 260540Z CIMSS D-MINT: 67 KTS AT 260522Z CIMSS D-PRINT: 57 KTS AT 260540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 0-5 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG DUAL-CHANNEL 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: TYPHOON (TY) 25W HAS REACHED THE RIDGE AXIS, DECELERATED SIGNIFICANTLY, AND IS COMMENCING A GRADUAL POLEWARD TURN. OVER THE NEXT 12 HOURS, 25W IS EXPECTED TO CONTINUE ITS SLOW NORTHWARD PROGRESSION, TURNING NORTHEASTWARD BY TAU 24. AFTER TAU 36, THE STR TO THE EAST RAPIDLY WEAKENS AND ELONGATES ALONG A SOUTHWEST- TO-NORTHEAST AXIS, WHILE SIMULTANEOUSLY A MODERATELY STRONG MID- LATITUDE SHORTWAVE TROUGH TRANSITS OVER SOUTHERN JAPAN. THIS LARGE- SCALE EVOLUTION WILL FACILITATE FULL RECURVATURE AND DOWNSTREAM ACCELERATION NORTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE SYSTEM WILL PASS SOUTHEAST OF TOKYO BY TAU 120 AS IT INITIATES EXTRATROPICAL TRANSITION (ETT). REGARDING INTENSITY: 25W RESIDES IN A NEAR-OPTIMAL ENVIRONMENT SUPPORTED BY A VERTICALLY ALIGNED VORTEX, HIGH OCEAN HEAT CONTENT, MINIMAL SHEAR, AND VIGOROUS DUAL-CHANNEL DIVERGENCE ALOFT. THE SYSTEM IS ANTICIPATED TO COMMENCE RAPID INTENSIFICATION (RI) SHORTLY, ATTAINING A PEAK OF AT LEAST 95 KNOTS NEAR TAU 24. THESE OPTIMAL CONDITIONS WILL BE TRANSIENT; BY TAU 36, THE SYSTEM WILL INITIATE A SLOW WEAKENING TREND AS UPPER-LEVEL OUTFLOW CHANNELS DIMINISH. MORE PRONOUNCED WEAKENING IS PROJECTED AFTER TAU 48 AS PROGRESSIVELY INCREASING VWS AND ENTRAINMENT OF DRY MID-LEVEL AIR DISRUPT CORE SYMMETRY. WEAKENING WILL CONTINUE THROUGH TAU 120. AN ALTERNATIVE SCENARIO CANNOT BE ENTIRELY DISCOUNTED, AS THE GFS CONTINUES AS A PERSISTENT DYNAMICAL OUTLIER DEPICTING A RETROGRADE EVOLUTION. THE PRIMARY GOVERNING MECHANISMS GENERATING THIS DIVERGENCE ARE (1) THE FORECAST INTENSITY AND CORE STRUCTURE OF 25W, (2) THE GENESIS AND INTENSIFICATION RATE OF A SECONDARY CYCLONE NEAR THE MARIANAS AND THEIR COMBINED IMPACT ON THE STR, AND (3) THE AMPLITUDE OF THE MID-LATITUDE TROUGH. THE GFS MAINTAINS 25W AS A DEEPER, MORE INTENSE CYCLONE FOR AN EXTENDED DURATION AND RAPIDLY DEVELOPS THE DOWNSTREAM MARIANAS CYCLONE. IN THE GFS SOLUTION, THESE TWO EXPANSIVE CIRCULATIONS AMPLIFY THE STR DOWNSTREAM, EFFECTIVELY PRECLUDING 25W FROM REACHING THE TROUGH INTERACTION ZONE (WHICH THE GFS SIMULTANEOUSLY RESOLVES AS WEAKER AND LESS DYNAMICALLY SUPPORTIVE). CONSEQUENTLY, THE GFS ARRESTS 25W NEAR THE LATITUDE OF OKINAWA BEFORE STEERING IT SOUTHWESTWARD ALONG THE EASTERN PERIPHERY OF STR OVER CHINA THROUGH TAU 120. MODEL DISCUSSION: TRACK GUIDANCE REMAINS BIFURCATED BETWEEN THE AI/ML SUITES (ALONGSIDE DETERMINISTIC ECMWF) SUPPORTING THE JTWC FORECAST AND THE GFS (WITH SECONDARY TENDENCIES IN GEFS AND NAVGEM) REFLECTING THE ALTERNATE SCENARIO. THROUGH TAU 36, GUIDANCE REMAINS IN TIGHT CONSENSUS, EXHIBITING MINIMAL CROSS-TRACK AND MODEST ALONG- TRACK DISPERSION. POST-RECURVATURE, HOWEVER, NUMERICAL SOLUTIONS DIVERGE RAPIDLY IN ALONG-TRACK TRANSLATION. NAVGEM TRANSLATES SLOWLY NORTHEASTWARD AFTER TAU 36, ULTIMATELY REACHING THE VICINITY OF YAKUSHIMA BY TAU 120. GFS REACHES THE LATITUDE OF OKINAWA AT TAU 72 PRIOR TO EXECUTING A 180-DEGREE RETROGRADE MOTION BACK TO THE SOUTHWEST, RETURNING TO NEAR ITS CURRENT COORDINATES BY TAU 120. CONVERSELY, THE AI MODELS CLUSTER POLEWARD OF 34N BY TAU 120, WITH OUTLIERS AS FAR NORTH AS 36N ADVECTED WELL TO THE EAST. THE DETERMINISTIC ECMWF IS POSITIONED POLEWARD OF THE AI CONSENSUS AT TAU 120, CLOSELY ALIGNED WITH THE UKMET ENSEMBLE MEAN. THE RESULTANT CROSS-REGIME SPREAD EXCEEDS 1000 NM. THE JTWC FORECAST HEAVILY FAVORS THE AI CONSENSUS MEAN THROUGH THE PERIOD; CONFIDENCE REMAINS MEDIUM THROUGH TAU 72, BUT IS ASSESSED AS LOW BEYOND TAU 72 DUE TO EXTREME MULTI-MODEL DISPERSION. INTENSITY GUIDANCE EXHIBITS GENERAL AGREEMENT THROUGH TAU 72, WITH NEARLY ALL GUIDANCE DEPICTING A SHARP PEAK AT TAU 24 WITHIN A 75-110 KNOT ENVELOPE. MULTIPLE STATISTICAL RI AIDS ARE TRIGGERED THIS CYCLE, AND HAFS-A DYNAMICALLY RESOLVES AN RI CYCLE. WHILE THE JTWC INTENSITY FORECAST REMAINS JUST BELOW CRITERIA FOR EXPLICIT RI, A PEAK EXCEEDING 100 KNOTS REMAINS A DISTINCT DYNAMICAL POSSIBILITY GIVEN OPTIMAL CORE ORGANIZATION. GRADUAL DECAY WILL FOLLOW PEAK INTENSITY THROUGH THE REMAINDER OF THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN