WDPN31 PGTW 020300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 025// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.7N 153.5E INITIAL INTENSITY: 125 KTS GEOGRAPHIC REFERENCE: 681 NM EAST OF IWO TO MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 54 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A MATURE, DONUT-SHAPED TYPHOON FEATURING A LARGE, 30 NM WIDE EYE EMBEDDED WITHIN A CENTRAL DENSE OVERCAST THAT EXHIBITS A SMOOTH CANOPY, INDICATIVE OF EXPANDED AND ROBUST RADIAL OUTFLOW ALOFT. ON INFRARED IMAGERY ENHANCED BY THE BD CURVE, THE CDO IS DEFINED BY A SOLID RING OF COLD CLOUD TOPS INDICATED BY BLACK AND WHITE SHADES ATTEMPTING TO FULLY ENCIRCLE THE EYE, WITH A PERSISTENT CONVECTIVE BAND ALONG THE WESTERN PERIPHERY. THE SYSTEM APPEARS TO BE PREPARING FOR A FOURTH EYEWALL REPLACEMENT CYCLE (ERC). THE 011923Z SSMIS PASS INDICATES THAT AN INTENSE OUTER BAND HAS WRAPPED NEARLY 70 PERCENT AROUND THE PRIMARY EYEWALL. FURTHER INSIGHT WAS PROVIDED BY A 012324Z ASCAT-B PASS, WHICH REVEALED AN ASYMMETRIC WIND FIELD WITH LARGER WIND RADII IN THE NORTHERN SEMICIRCLE. THIS ASYMMETRY IS LIKELY THE RESULT OF MODEST BUT PERSISTENT SOUTHERLY MID-LEVEL VERTICAL WIND SHEAR (VWS). THE SURROUNDING ENVIRONMENT IS GENERALLY FAVORABLE, CHARACTERIZED BY VERY WARM SEA SURFACE TEMPERATURE, MODERATE OCEAN HEAT CONTENT (OHC), AND GOOD DIVERGENCE ALOFT OFFSET BY THE AFOREMENTIONED LOW TO MODERATE SHEAR. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE CIRCULAR, CLOUD-FREE EYE. AS THE CONVECTIVE STRUCTURE HAS NOT CHANGED SIGNIFICANTLY IN THE PAST 6 HOURS, THE INITIAL INTENSITY HAS BEEN HELD AT 125 KTS WITH MEDIUM CONFIDENCE, WHICH IS SUPPORTED BY THE T6.5 FROM PGTW AND RCTP AND THE HIGHER END OF THE OBJECTIVE ESTIMATES FROM CIMSS RANGING FROM 116 KTS TO 126 KTS. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHWESTERN EXTENSION OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T6.0 - 115 KTS RCTP: T6.5 - 127 KTS KNES: T6.0 - 115 KTS CIMSS SATCON: 126 KTS AT 012130Z CIMSS ADT: 117 KTS AT 020000Z CIMSS AIDT: 116 KTS AT 020000Z CIMSS D-MINT: 119 KTS AT 011940Z CIMSS D-PRINT: 120 KTS AT 020000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-20 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE RADIAL 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 12W WILL MAINTAIN ITS WEST-NORTHWESTWARD TRAJECTORY AT 13-14 KTS, STEERED ALONG THE SOUTHWESTERN PERIPHERY OF A STR CENTERED NEAR 43N 177W. THE WESTERN EXTENSION OF THIS RIDGE WILL CONTINUE TO BUILD, DRIVING THE SYSTEM IN THE SAME GENERAL DIRECTION. BY TAU 48, A SEPARATE RIDGE OVER THE KOREAN PENINSULA WILL BECOME THE DOMINANT STEERING MECHANISM, MAINTAINING THE WEST-NORTHWESTWARD MOTION AND GUIDING THE SYSTEM TOWARD A VERY CLOSE PASSAGE TO IWO TO. IN THE EXTENDED FORECAST, THE STORM'S FORWARD MOTION WILL DECREASE TO 10 KTS BY TAU 96. THE DECELERATION WILL BE CAUSED BY A LARGE CYCLONE OVER EASTERN SIBERIA, WHICH WILL ERODE THE RIDGE AND LEAD TO A WEAKER STEERING GRADIENT. TY 12W WILL IMMINENTLY EMBARK ON A GRADUAL, PROLONGED PERIOD OF WEAKENING. ALTHOUGH IT BRIEFLY INTENSIFIED AFTER ITS LAST ERC, THE SYSTEM WILL TRAVERSE OVER LOWER OHC, WHICH WILL BE INCAPABLE OF SUPPORTING A STORM OF ITS CURRENT HIGH INTENSITY. WHILE OTHER ENVIRONMENTAL FACTORS, SUCH AS LOWER VWS AND HIGH SST, WILL BE FAVORABLE, THE DIMINISHING OHC WILL BE THE PRIMARY DRIVER OF THE SLOW DECAY. CONSEQUENTLY, THE FORECAST LEVELS OFF THE WEAKENING TREND AT TAU 96. THE SYSTEM WILL LIKELY UNDERGO AT LEAST ONE ADDITIONAL ERC BEFORE REACHING THE RYUKYU ISLANDS. THIS WILL RESULT IN AN EVEN LARGER WIND FIELD AT TAU 96 AND TAU 120, CAUSING SIGNIFICANT IMPACTS TO EXTEND FAR FROM THE STORM'S CENTER. MODEL DISCUSSION: THE CROSS-TRACK SPREAD AMONG THE MODEL GUIDANCE IS TIGHT AND BETTER THAN THE CLIMATOLOGICAL AVERAGE. HOWEVER, THE ALONG-TRACK SPREAD INCREASES SIGNIFICANTLY IN THE EXTENDED PERIOD, FROM 95 NM AT TAU 72 TO 290 NM AT TAU 120. THIS DIVERGENCE IS DRIVEN BY DIFFERING FORWARD SPEEDS, WITH THE MORE POLEWARD TRACK SOLUTIONS TENDING TO MOVE THE SYSTEM FASTER. THE GFS, NAVGEM, AND GALWEM SOLUTIONS ARE SOUTH OF CONSENSUS AND THUS SLOWER, WHILE ECMWF, THE ECENS AND GEFS ENSEMBLE MEANS, AND THE AI MODEL CONSENSUS TRACKERS ARE FURTHER NORTH AND FASTER. THE JTWC FORECAST TRACK IS VIRTUALLY UNCHANGED FROM THE LAST FORECAST, POSITIONED WITH HIGH CONFIDENCE NEAR THE MULTI-MODEL CONSENSUS THROUGH TAU 60 AND THEN HEDGED POLEWARD OF CONSENSUS THROUGH TAU 120. THE INTENSITY AIDS DEPICT GRADUAL WEAKENING THROUGH THE FORECAST PERIOD, BUT WITH SIGNIFICANT SPREAD. COAMPS-TC IS THE HIGH-END OUTLIER, DEPICTING RE-INTENSIFICATION TO 135 KTS. THIS SCENARIO IS DISCOUNTED AS IT DOES NOT ALIGN WITH THE PREDICTED UPSTREAM ENVIRONMENT. HAFS-A IS THE MOST AGGRESSIVE IN WEAKENING THE SYSTEM DOWN TO 75 KTS BY TAU 120. THE HWRF AND EXPERIMENTAL GOOGLE DEEPMIND MODELS DEPICT GRADUAL WEAKENING THROUGH TAU 72 WITH LITTLE CHANGE IN INTENSITY THEREAFTER. THE JTWC INTENSITY FORECAST IS SET WITH HIGH CONFIDENCE FOR THE FIRST 72 HOURS AND MEDIUM CONFIDENCE FOR THE LATER PERIOD. IT DEPICTS GRADUAL WEAKENING IN CLOSEST ALIGNMENT WITH THE HWRF AND DEEPMIND SOLUTIONS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN