WDPN33 PGTW 290900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (ROKE) WARNING NR 005// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.8N 132.2E INITIAL INTENSITY: 70 KTS GEOGRAPHIC REFERENCE: 241 NM EAST OF KADENA AB, OKINAWA, JAPAN MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 22 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A COMPACT SYSTEM THAT HAS SIGNIFICANTLY DEEPENED AND INTENSIFIED OVER THE LAST SIX HOURS. A RAGGED BUT DEFINED 7X14 NM ELONGATED EYE HAS EVOLVED AND CONVECTIVE TOPS ALONG THE SEMI-CIRCULAR EYEWALL HAVE COOLED TO -82C. POLEWARD OUTFLOW HAS ALSO FURTHER IMPROVED AS EVIDENCE BY CIRRUS TRANSVERSE BANDING NOW EXTENDING FURTHER NORTH AND DEEP INTO THE PREVAILING WESTERLIES. THE INITIAL POSITION IS BASED ON THE DEFINED EYE AND SUPPORTED BY A TIGHT CLUSTER OF AGENCY, AUTOMATED, AND RJTD RADAR FIXES. THE INITIAL INTENSITY OF 70KTS IS BASED ON THE HIGH END OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE 6-HR RAPID INTENSIFICATION. INITIAL WIND RADII BASIS: SCATTEROMETER DATA AND SURFACE WIND OBSERVATIONS. CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T3.5 - 55 KTS KNES: T4.5 - 77 KTS CIMSS ADT: 72 KTS AT 290550Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY ROKE HAS CRESTED THE STR RIDGE AXIS AND WILL NOW ACCELERATE NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR. BY TAU 48, A SECONDARY STR TO THE NORTH WILL COMPETE FOR STEERING AND STALL TY 20W IN A SLOW OR EVEN QUASI-STATIONARY MOTION. THE FAVORABLE ENVIRONMENT WILL FUEL SLIGHT INTENSIFICATION OVER THE NEXT 12 HRS; AFTERWARD, CONDITIONS WILL SLOWLY BECOME UNFAVORABLE AS VWS INCREASES WITH FURTHER ADVANCE INTO THE STRONG WESTERLIES. ADDITIONALLY, WITH THE ENCROACHMENT OF THE SECONDARY STR, UPPER LEVEL SUBSIDENCE WILL ALSO SUPPRESS VERTICAL DEVELOPMENT. THESE, IN ADDITION TO COOLING SST SOUTHEAST OF JAPAN (BELOW 27C) WILL REDUCE THE SYSTEM TO 30KTS BY TAU 120. MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT WITH GRADUAL SPREADING TO JUST 150NM BY TAU 72. AFTERWARD, THE TRACKERS SIGNIFICANTLY DIVERGE ACROSS- AND ALONG-TRACK, LENDING HIGH CONFIDENCE IN THE NEAR- TO MID-PORTION OF THE FORECAST AND LOW CONFIDENCE AFTERWARD. THERE IS MEDIUM CONFIDENCE IN THE INTENSITY FORECAST UP TO TAU 72, THEN LOW CONFIDENCE AFTERWARD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN