WDPN31 PGTW 240300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 18W (JELAWAT) WARNING NR 15// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 18W (JELAWAT), LOCATED APPROXIMATELY 440 NM EAST OF MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 05 KNOTS OVER THE PAST SIX HOURS. STY 18W HAS DISCONTINUED ITS RAPID INTENSIFICATION PHASE BUT REMAINS AT SUPER TYPHOON STRENGTH. ANIMATED MULTISPECTRAL (MSI) SATELLITE IMAGERY CONTINUALLY SHOWS AN ERRATIC, BUT GENERALLY POLEWARD MOTION. MSI ALSO DEPICTS A VERY WELL DEVELOPED SYSTEM WITH A 10NM ROUND EYE AND STRONG SPIRAL BANDING. A 242113Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS A WELL DEVELOPED RING OF DEEP CONVECTION SURROUNDING THE EYE WITH SLIGHT WEAKENING TO THE CONVECTION IN THE NORTHWEST QUADRANT. THE INITIAL INTENSITY IS ASSESSED AT 130 KNOTS BASED ON AN AGREEMENT OF DVORAK ESTIMATES OF 127 KNOTS FROM PGTW, RJTD, AND KNES. THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION AND RECENT MOTION BASED ON THE SMALL EYE EVIDENT IN THE MSI. STY 18W REMAINS EMBEDDED WITHIN A COMPLEX, WEAK STEERING ENVIRONMENT RESULTING FROM THE PERSISTENT TROUGHING PRESENT OVER ASIA AND THE PRESENCE OF NOW TROPICAL DEPRESSION (TD) 19W, LOCATED ABOUT 675 NM TO THE EAST-NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS REASONING MESSAGE. B. TY 18W IS FORECAST TO TRACK SLOWLY NORTH-NORTHWESTWARD THROUGH TAU 36 UNDER THE STEERING INFLUENCE OF A BUILDING NEAR-EQUATORIAL RIDGE (NER) TO THE EAST. AS TD 19W TRACKS NORTH-NORTHWESTWARD, THE NER IS EXPECTED TO STRENGTHEN TO THE EAST AND NORTHEAST OF STY 18W, PROVIDING A NORTHWESTWARD STEERING INFLUENCE. AFTER TAU 36, A SHORTWAVE TROUGH CURRENTLY OVER JAPAN WILL TRACK EASTWARD AND THE STR WILL BUILD NORTH OF THE SYSTEM, WHICH WILL ALLOW STY 18W TO TURN NORTHWESTWARD THROUGH TAU 96. DYNAMIC MODEL GUIDANCE HAS BECOME MORE IN AGREEMENT WITH NOGAPS, GFS, JGSM, AND ECMWF BEING GROUPED FAIRLY CLOSE TOGETHER. HOWEVER, GFDN AND EGRR CONTINUE TO BE THE RIGHT MOST OUTLIERS. DUE TO THE COMPLEX ENVIRONMENT, FORECAST CONFIDENCE REMAINS LOW. STY 18W IS EXPECTED TO SLIGHTLY STRENGTHEN FOR THE NEXT 24 TO 36 HOURS AT A PEAK OF 135 KNOTS AND SHOULD GRADUALLY WEAKEN THROUGH THE REMAINDER OF THE FORECAST AS STY 18W MOVES INTO HIGHER LATITUDES . C. IN THE EXTENDED TAUS, THE JTWC FORECAST CONTINUES TO BE WEST OF CONSENSUS TO OFFSET THE GFDN AND EGRR TRACKS. AT TAU 120, STY 18W IS FORECAST TO BEGIN A RE-CURVE TOWARDS OKINAWA, JAPAN, IN RESPONSE TO ANOTHER DEEP SHORTWAVE TROUGH, WHICH IS FORECAST TO TRACK INTO EASTERN CHINA AFTER TAU 96. ALTHOUGH THERE IS A LARGE SPREAD IN THE MODELS, THEY ALL NOW SHOW THIS RECURVE MOTION AT TAU 120. THERE IS LOW CONFIDENCE IN THE EXTENDED TRACK DUE TO THE LARGE MODEL SPREAD.// NNNN