MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (NEOGURI) WARNING NR 21// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 08W (NEOGURI), LOCATED APPROXIMATELY 133 NM SOUTHWEST OF KADENA AB, OKINAWA, HAS TRACKED NORTHWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY IN COMBINATION WITH RADAR IMAGERY FROM ISHIGAKIJIMA INDICATE THE EYEWALL HAS MAINTAINED ITS OVERALL STRUCTURE FOR THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS SOME DIURNAL FLARING WITHIN THE EYEWALL. A RECENT 072313Z TRMM MICROWAVE PASS REVEALS THE EYEWALL CONTINUES TO BE WEAKEST ALONG THE NORTHWESTERN QUADRANT. THE CURRENT INTENSITY HAS BEEN KEPT AT 110 KNOTS, SLIGHTLY HIGHER THAN THE DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD, WHICH HAVE INCREASED ASSOCIATED WITH THE RECENT FLARE OF CONVECTION OBSERVED IN WATER VAPOR IMAGERY. THE EYE DIAMETER HAS PERSISTED AT 30 NM OVER THE PAST SIX HOURS. A DIGGING MID-LATITUDE TROUGH, TO THE NORTHWEST OF TY 08W, HAS BEEN AMPLIFYING THE UPPER LEVEL POLEWARD OUTFLOW OVER THE PAST 18 HOURS, HELPING TO MAINTAIN THE INTENSITY OF THE SYSTEM. RECENTLY, AS THE TROUGH CONTINUES TO DIG TO THE SOUTHWEST, OVER EASTERN CHINA, INCREASED SUBSIDENCE ALONG THE NORTHWESTERN QUADRANT OF TY 08W HAS HINDERED DEVELOPMENT. THE TRACK APPEARS TO BE ON A MORE NORTHWARD TRACK OVER THE PAST SIX HOURS BASED ON RECENT ANIMATED RADAR IMAGERY. TY 08W TRACKS ALONG THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) ANCHORED NEAR IWO TO. TRACK SPEEDS HAVE BEEN CONSISTENT OVER THE PAST 18 HOURS. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 08W IS FORECAST TO TRACK NORTHWARD OVER THE NEXT SIX HOURS. THE DIGGING MID-LATITUDE TROUGH TO THE NORTHWEST OF TY 08W WILL TRACK EASTWARD AND CAUSE THE STR TO SHIFT AFTER TAU 24, CAUSING TY 08W TO TRACK EAST-NORTHEASTWARD AFTER TAU 36. THE TROUGH HAS BEEN AMPLIFYING THE UPPER LEVEL POLEWARD OUTFLOW OVER THE PAST 12 HOURS, HELPING TO MAINTAIN THE INTENSITY OF THE SYSTEM BUT AS IT SHIFTS EASTWARD, THE TROUGH WILL STIFLE THE STRONG POLEWARD OUTFLOW, LEADING TO A STRONGER WEAKENING TREND BY TAU 48. LANDFALL IN SOUTHERN JAPAN IS EXPECTED AROUND 00Z ON THE 10TH. THE SEA SURFACE TEMPERATURES REMAIN VERY FAVORABLE THROUGH TAU 24, BUT WILL QUICKLY DECREASE ONCE THE SYSTEM APPROACHES 30N. INCREASING VERTICAL WIND SHEAR FROM THE MID-LATITUDE WESTERLIES WILL ALSO BEGIN TO IMPACT THE STRUCTURE OF TY 08W AFTER TAU 36. BEYOND TAU 48 A COMBINATION OF THESE ELEMENTS, IN ASSOCIATION WITH THE TRACK OVER THE SOUTHERN JAPANESE TERRAIN, WILL LEAD TO A THE BEGINNING OF EXTRA-TROPICAL TRANSITION (ETT) BY TAU 48. C. BEYOND TAU 72, TY NEOGURI WILL CONTINUE THE ETT PROCESS, ACCELERATING TO THE NORTHEAST UNDER THE COMBINED INFLUENCE OF A DEEP MID-LATITUDE LOW OVER NORTHERN JAPAN AND THE STR. TY NEOGURI IS EXPECTED TO BY FULLY EXTRA-TROPICAL BY TAU 96. THE AVAILABLE DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING TO HIGH CONFIDENCE IN THE JTWC TRACK FORECAST TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN