MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 20W (HAGIBIS) WARNING NR 027// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 20W (HAGIBIS), LOCATED APPROXIMATELY 300 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHWARD AT 09 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) SHOWS CONVECTIVE BANDING WRAPPING INTO A SYMMETRIC LOW LEVEL CIRCULATION CENTER (LLCC). OVER THE PAST SIX HOURS, CONVECTION HAS OBSCURED THE PREVIOUSLY WELL-DEFINED EYE. THE INITIAL POSITION IS BASED ON EIR AND RECENT SATELLITE FIXES FROM PGTW AND RJTD. BASED ON DVORAK CURRENT INTENSITY ESTIMATES OF T6.0/115 KTS (PGTW) AND T5.5/102 KTS (RJTD), THE INITIAL INTENSITY IS SET AT 105 KTS WITH GOOD CONFIDENCE, SLIGHTLY LOWER THAN A TIME-LATE 111117Z SATELLITE CONSENSUS ESTIMATE OF 108 KTS. THE SYSTEM IS SHOWING SLIGHT WEAKENING AS IT BEGINS TO BE SHEARED BY THE MID-LATITUDE WESTERLIES. TY 20W IS TRANSITING THROUGH A REGION OF MODERATE (20-25 KTS) VERTICAL WIND SHEAR (VWS), WARM (27-28 CELSIUS) SEA SURFACE TEMPERATURES (SST), AND EXCELLENT POLEWARD OUTFLOW. TY 20W IS TRACKING POLEWARD STEERED BY A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. OVER THE NEXT 12 HOURS, TY 20W WILL GRADUALLY TURN NORTHEASTWARD AS IT APPROACHES THE ISLAND OF HONSHU UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR. PRIOR TO LANDFALL, INCREASING VWS WILL CAUSE TY 20W TO STEADILY WEAKEN AS THE UPPER-LEVEL OUTFLOW IS SHEERED BY THE MID-LATITUDE TROUGH. ADDITIONALLY, AS THE NORTHERN PORTION OF THE SYSTEM INTERACTS WITH LAND, FRICTIONAL EFFECTS WILL ALSO ERODE THE SYSTEM. AROUND TAU 18, THE SYSTEM CENTER IS EXPECTED TO PASS VERY CLOSE TO THE TOKYO AREA. AFTERWARDS, THE SYSTEM WILL ACCELERATE NORTHEASTWARD AS IT BECOMES FULLY EMBEDDED WITHIN THE MID-LATITUDE TROUGH AND BEGINS EXTRATROPICAL TRANSITION EAST OF HONSHU. BY TAU 36, TY 20W WILL BE A STRONG EXTRATROPICAL LOW PRESSURE SYSTEM. NUMERICAL MODEL GUIDANCE IS IN EXCELLENT AGREEMENT WITH RESPECT TO FORWARD SPEED AND SYSTEM DIRECTION, RESULTING IN HIGH CONFIDENCE TO THE JTWC FORECAST TRACK WHICH IS PLACED CLOSE TO MODEL CONSENSUS.// NNNN NNNN