MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (TRAMI) WARNING NR 11// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 28W (TRAMI), LOCATED APPROXIMATELY 660 NM SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A 130NM DIAMETER CENTRAL DENSE OVERCAST FEATURE WITH A 10NM RAGGED EYE. A 230438Z AMSR2 89GHZ IMAGE INDICATES A RAPIDLY CONSOLIDATING SYSTEM WITH SPIRAL BANDING WRAPPING INTO A COMPACT EYEWALL AND MICROWAVE EYE FEATURE, WHICH SUPPORTS THE CURRENT POSITION WITH HIGH CONFIDENCE. TY TRAMI HAS RAPIDLY INTENSIFIED 45 KNOTS OVER THE PAST 24 HOURS FROM 50 KNOTS TO THE CURRENT INTENSITY OF 95 KNOTS, WHICH IS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM T5.0 (90 KNOTS) TO T5.5 (102 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH NEAR-RADIAL OUTFLOW, ENHANCED BY A TUTT CELL TO THE NORTHEAST, AND LOW VERTICAL WIND SHEAR. TY 28W IS TRACKING WEST-NORTHWESTWARD ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. THE INITIAL 34-KNOT WIND RADII HAVE BEEN ADJUSTED BASED ON A DETAILED ANALYSIS OF THE 230017Z ASCAT IMAGE. B. TS TRAMI IS FORECAST TO TRACK WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE AFOREMENTIONED STR THROUGH TAU 36. AFTER TAU 36, A MIDLATITUDE SHORTWAVE TROUGH WILL DEEPEN OVER THE EAST CHINA SEA AND WESTERN JAPAN CREATING A BROAD, PERSISTENT BREAK IN THE STR. THIS WILL RESULT IN A SLIGHT POLEWARD TURN AND SIGNIFICANT DECREASE IN TRACK SPEEDS AS THE STEERING INFLUENCE ERODES QUICKLY. TRACK SPEEDS ARE EXPECTED TO REMAIN SLOW THROUGH TAU 72 AS THE STR SLOWLY REBUILDS TO THE NORTH AND THE SYSTEM RETURNS TO A WEST-NORTHWESTWARD COURSE. WITH THE EXCEPTION OF HWRF AND GFS, NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH A 120NM SPREAD IN SOLUTIONS AT TAU 72, HOWEVER, THERE IS SIGNIFICANT UNCERTAINTY IN THE TRACK / TRACK SPEEDS DURING THE TAU 48 TO TAU 72 PERIOD WITH AN ERRATIC TRACK POSSIBLE. THE SYSTEM IS EXPECTED TO INTENSIFY TO SUPER TYPHOON STRENGTH BY TAU 36 UNDER VERY FAVORABLE CONDITIONS WITH A PEAK INTENSITY OF 140 KNOTS ANTICIPATED BY TAU 72. C. AFTER TAU 72, NUMERICAL MODEL GUIDANCE INDICATES INCREASING SPREAD AND GREATER UNCERTAINTY IN THE EXACT FORECAST TRACK WITH A 330NM SPREAD IN SOLUTIONS AT TAU 120 (EXCLUDING THE HWRF AND GFS OUTLIERS). THE GFS AND HWRF SOLUTIONS SHOW A SHARP NORTHWARD TRACK TOWARD THE RYUKYU ISLANDS IN THE EXTENDED PERIOD WHICH IS DEEMED UNLIKELY DUE TO EXCESSIVE INTERACTION WITH THE MIDLATITUDE SHORTWAVE TROUGH. THE JTWC OFFICIAL FORECAST FAVORS A SLOW, WEST-NORTHWESTWARD TRACK TOWARD TAIWAN AND ISHIGAKI-JIMA AS SUPPORTED BY THE BULK OF THE MODEL GUIDANCE. TY 28W IS FORECAST TO WEAKEN SLIGHTLY AFTER TAU 72 AS ENVIRONMENTAL CONDITIONS DEGRADE. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC TRACK DUE TO THE LARGE SPREAD IN SOLUTIONS AFTER TAU 72.// NNNN NNNN