WDPN31 PGTW 012100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 27W (NYATOH) WARNING NR 010// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.0N 135.7E INITIAL INTENSITY: 70 KTS GEOGRAPHIC REFERENCE: 414 NM NORTH-NORTHWEST OF YAP MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 26 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY INDICATES THAT THE SYSTEM CONTINUES TO SLOWLY CONSOLIDATE, WITH VERY COLD (-92C) CONVECTIVE CLOUD TOPS INDICATIVE OF VORTICAL HOT TOWERS BEGINNING TO WRAP AROUND THE ASSESSED CENTER. WHILE THE SYSTEM HAS NOT YET FORMED AN EYE IN THE EIR, A 161622Z AMSR2 MICROWAVE IMAGE SHOWED A WELL DEFINED MICROWAVE EYE IN THE 89GHZ BAND, AND A WEAKER BUT STILL DEFINED MICROWAVE EYE FEATURE IN THE 36GHZ BAND, SUGGESTING THE DEVELOPMENT OF AN EYE IN THE EIR IS LIKELY IMMINENT. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON AN EXTRAPOLATION OF THE MICROWAVE EYE IN THE AMSR2 IMAGERY, WHICH LINES UP WELL WITH AGENCY DVORAK FIX POSITIONS. THE INITIAL INTENSITY OF 70 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON AN AVERAGE OF THE AGENCY CURRENT INTENSITY ESTIMATES BETWEEN T3.5 AND T4.5, THE SATCON ESTIMATE AND IN LINE WITH THE MAXIMUM WINDS EVIDENT IN THE AMSR2 WINDSPEED PRODUCT. CIMSS ADT IS UNREALISTICALLY LOW AT 59 KNOTS, AS IT IS BASING ITS ESTIMATE ON A UNIFORM CDO METHOD, VICE THE BANDING EYE OR CURVED BAND METHOD. TY 27W IS IN THE PROCESS OF ROUNDING THE DEEP-LAYER RIDGE TO THE EAST, TRACKING THROUGH AN EXCELLENT ENVIRONMENT OF LOW VWS, WARM SSTS AND VERY STRONG POLEWARD OUTFLOW. INITIAL WIND RADII BASIS: OTHER; 011622Z AMSR2 WINDSPEED PRODUCT. CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF THE DEEP-LAYER SUBTROPICAL RIDGE TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T4.0 - 65 KTS RCTP: T3.5 - 55 KTS KNES: T4.5 - 77 KTS CIMSS SATCON: 68 KTS AT 011248Z CIMSS ADT: 59 KTS AT 011740Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD 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. HOWEVER THE FORECAST HAS BEEN TRUNCATED TO 96 HOURS. FORECAST DISCUSSION: AFTER REACHING THE RIDGE AXIS, TY 27W IS NOW BEGINNING TO ACCELERATE TOWARDS THE NORTH, AND IS EXPECTED TO GRADUALLY TURN NORTHEASTWARD OVER THE NEXT 12 TO 24 HOURS. THE SYSTEM WILL REMAIN IN A HIGHLY FAVORABLE ENVIRONMENT FOR ANOTHER 18-24 HOURS OR SO, WITH WARM SSTS, AND HIGH OHC PROVIDING A LARGE AMOUNT OF ENERGY TO THE SYSTEM. A VERY DEEP TROUGH PASSING THROUGH JAPAN AT THE CURRENT TIME IS ENHANCING POLEWARD OUTFLOW, WHICH COMBINED WITH THE LOW VWS, WILL SUPPORT A PERIOD OF STEADY, NEAR-RAPID, INTENSIFICATION TO A PEAK OF 95 KNOTS BY TAU 24. THE PEAK WILL BE SHORT-LIVED HOWEVER, AS BY TAU 36, SHEAR IS FORECAST TO RAPIDLY INCREASE. COOLER, DRIER AIR ASSOCIATED WITH A STRONG COLD FRONT WILL BEGIN WRAPPING INTO THE SYSTEM BY TAU 36, AND THE COMBINED EFFECTS OF THE SHEAR AND DRY AIR WILL LEAD TO RAPID WEAKENING AFTER TAU 36. VWS IS FORECAST TO STEADILY INCREASE THEREAFTER, REACHING 50-60 KNOTS BY TAU 72, WHICH WILL DECAPITATE THE SYSTEM. THE REMNANT LOW LEVEL VORTEX WILL DRIFT SOUTHWARD UNDER THE INFLUENCE OF THE LOW LEVEL STEERING FLOW. THE SYSTEM IS EXPECTED TO DISSIPATE BELOW WARNING CRITERIA NO LATER THAN TAU 96. MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48, WITH ALL CONSENSUS MEMBERS TIGHTLY PACKED IN A 70NM ENVELOPE, THOUGH ALONG TRACK SPREAD INCREASES AFTER TAU 24, WITH THE ECMWF AND ECMWF ENSEMBLES RACING AHEAD OF OTHER CONSENSUS MEMBERS. AFTER TAU 72, THE MODELS SHOW SIGNIFICANT UNCERTAINTY IN THE FORECAST TRACK, WITH THE ECMWF, ECMWF ENSEMBLE, EGRR AND JGSM TAKING THE LOW LEVEL VORTEX RAPIDLY NORTHEAST ALONG THE FRONTAL BOUNDARY. THE REMAINDER OF THE GUIDANCE INCLUDING GFS, GFS ENSEMBLE, NAVGEM AND HWRF, SHOW THE SYSTEM REACHING THE 25TH LATITUDE, STOPPING, THEN TURNING SHARPLY SOUTHWARD AS THE SYSTEM DISSIPATES. THE JTWC FORECAST TRACKS THE CONSENSUS THROUGH TAU 48, THEN FAVORS THE GFS AND NAVGEM SOLUTION THROUGH TAU 96. INTENSITY GUIDANCE IS MIXED, WITH HWRF INDICATING RAPID INTENSIFICATION THROUGH TAU 24. THE RAPID INTENSIFICATION PREDICTION AID (RIPA) IS ALSO TRIGGERED, HOWEVER THE REMAINDER OF THE GUIDANCE PACKAGE IS SIGNIFICANTLY LESS BULLISH, INDICATING A PEAK NEAR 80 KNOTS. THE JTWC FORECAST LIES ABOUT 10 KNOTS HIGHER THAN THE CONSENSUS MEAN, THOUGH BELOW THE HWRF AND RIPA PEAKS. AFTER TAU 24, THE FORECAST LIES JUST SLIGHTLY HIGHER THAN THE CONSENSUS MEAN THROUGH THE REMAINDER OF THE FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN