WDPN31 PGTW 261500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 18W (JELAWAT) WARNING NR 25// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 18W (JELAWAT), LOCATED APPROXIMATELY 495 NM SOUTH-SOUTHWEST OF KADENA AIR BASE, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS COMPLETED AN EYEWALL REPLACEMENT OVER THE PAST 24 HOURS, ENDING IN A BIGGER 25-NM EYE. THIS IS CORROBORATED BY A SERIES OF MICROWAVE IMAGERY INCLUDING ONE FROM A 261112Z SSMI-S PASS. THE INITIAL INTENSITY WAS BASED FROM THE ABOVE ANIMATION AND MICROWAVE IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY ON THE HIGH END OF DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES THE CYCLONE HAS MAINTAINED A MESOSCALE ANTICYCLONE OVERHEAD AND IS APPROACHING A RIDGE AXIS TO THE NORTH IN AN AREA OF LOW (05-10 KNOT) VERTICAL WIND SHEAR. ANIMATED WATER VAPOR IMAGERY SHOWS CONTINUED EXCELLENT RADIAL OUTFLOW ENHANCED BY A POLEWARD STREAM INTO THE BACK END OF A MID-LATITUDE SHORTWAVE THAT PASSED EASTWARD TO THE NORTH AND IS NOW TO THE NORTHEAST. HOWEVER, THE SAME ANIMATION ALSO INDICATES CIRRI TRANSVERSE BANDING ALONG THE NORTHWEST QUADRANT, INDICATING VERY STRONG UPPER LEVEL WINDS. STY 18W IS TRACKING ALONG SOUTHWESTERN PERIPHERY OF AN EXTENSION OF THE NEAR-EQUATORIAL RIDGE (NER)TO THE EAST THAT HAS SINCE REBUILT AFTER THE TROUGH PASSAGE. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. STY 18W WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD OVER THE NEXT 24 HOURS ALONG THE SOUTHWESTERN PERIPHERY OF THE NER. AFTERWARDS, A SECONDARY MID-LATITUDE TROUGH, CURRENTLY EXITING INTO THE YELLOW SEA, WILL APPROACH FROM THE NORTHWEST AND WEAKEN THE NER ANEW CAUSING THE SYSTEM TO RECURVE NORTHEASTWARD. AFTER TAU 48, THE SUBTROPICAL RIDGE (STR) EAST OF JAPAN, ALSO WEAKENED BY THE SAME TROUGH, WILL SEAMLESSLY ASSUME STEERING AND CAUSE 18W TO ACCELERATE NORTHEASTWARD. DURING THIS PORTION OF THE FORECAST, THE SYSTEM WILL GRADUALLY WEAKEN AS THE UPPER LEVEL CONDITIONS DETERIORATE. C. IN THE EXTENDED PERIOD, STEERED BY THE STR, STY 18W WILL CONTINUE TO ACCELERATE NORTHEASTWARD INTO THE BAROCLINIC ZONE, BECOMING AN EXTRA-TROPICAL LOW BY END OF FORECAST AND AFTER LANDFALL IN HONSHU, JAPAN. THE CYCLONE WILL GRADUALLY WEAKEN AS IT ENCOUNTERS INCREASING VWS, COOLER SEA SURFACE TEMPERATURES, AND FINALLY, LANDMASS. THE MODELS CONTINUE TO COME INTO BETTER AGREEMENT, ALTHOUGH GFDN AND NOGAPS CONTINUE TO SHOW AN UNREALISTIC ACCELERATION INTO THE WESTERLIES. THE CURRENT TRACK FORECAST IS SLIGHTLY SLOWER THAN THE CONSENSUS TO OFFSET GFDN AND NOGAPS. THERE REMAINS LOW CONFIDENCE IN THE EXTENDED FORECAST TRACK. // NNNN