MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 31W (YUTU) WARNING NR 23// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 31W (YUTU), LOCATED APPROXIMATELY 811 NM EAST- NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A MORE SYMMETRIC SYSTEM THAT HAS MAINTAINED A RAGGED 27-NM EYE WITH COMPACT RAIN BANDS WRAPPING TIGHTLY INTO THE CENTRAL CONVECTION WITH SUPER-DEEP AND COLD CLOUD TOPS (-82 CELSIUS). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI EYE THAT LINED UP PERFECTLY WITH A MICROWAVE EYE IN THE 262115Z SSMIS 37 GHZ PASS. THE INITIAL INTENSITY OF 140 KNOTS IS BASED ON EQUIVALENT AND NEARLY CONCENTRIC DVORAK ESTIMATE FIXES OF T7.0 FROM PGTW AND RJTD. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW 10-15 KNOT) RELATIVE EASTERLY VERTICAL WIND SHEAR (VWS) AND ROBUST RADIAL OUTFLOW WITH A STRONG POLEWARD CHANNEL. SST AND OHC VALUES IN THE PHILIPPINE SEA ARE ALSO VERY CONDUCIVE. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. STY 31W IS FORECAST TO CONTINUE TRACKING WESTWARD THROUGH TAU 36. AFTERWARD, IT SHOULD GRADUALLY TURN MORE WEST-SOUTHWESTWARD AS THE STR TO THE NORTHEAST BUILDS AND EXTENDS WESTWARD. THE FAVORABLE ENVIRONMENT WILL PREVAIL AND EXTEND THE INTENSIFICATION TO A PEAK OF 145 KNOTS BY TAU 12. AFTERWARD, DIMINISHING OUTFLOW AS THE CYCLONE MOVES FARTHER AWAY FROM THE TROUGH-ENHANCED POLEWARD OUTFLOW WILL SLOWLY WEAKEN STY 31W DOWN TO 120 KNOTS BY TAU 72. NUMERICAL MODEL GUIDANCE REMAINS IN GOOD AGREEMENT WITH GRADUAL SPREADING UP TO 340 NM BY TAU 72. NVGM AND CTCX - OUTLIERS ON THE RIGHT SIDE OF THE MODEL ENVELOPE - CONTINUE TO PROMOTE AN EARLY RECURVATURE. THERE IS FAIR CONFIDENCE IN THIS PORTION OF THE JTWC TRACK FORECAST THAT IS LAID JUST LEFT OF CONSENSUS TO OFFSET THE UNLIKELY EARLY RECURVATURE. C. BEYOND TAU 72, STY YUTU WILL TRACK TOWARD THE NORTHERN TIP OF LUZON ON A MORE WEST-NORTHWESTWARD TRAJECTORY AS THE STR WEAKENS IN RESPONSE TO AN APPROACHING MID-LATITUDE TROUGH AND BY TAU 120 WILL BE IN THE MIDDLE OF LUZON STRAIT. IN ADDITION TO THE DIMINISHED OUTFLOW, INCREASING VWS AND LAND INTERACTION WILL WEAKEN THE SYSTEM AT A FASTER RATE, DOWN TO 90 KNOTS BY TAU 120. THERE IS SIGNIFICANT SPREADING IN THE NUMERICAL MODELS - OVER 880 NM AT TAU 120. CTCX AND NVGM ARE THE EXTREME EARLY RECURVE RIGHT-OF-TRACK OUTLIERS, AND JGSM AND AFUM ARE ON THE FAR LEFT WITH A STRAIGHT WESTWARD AND LATE RECURVE SOLUTION. IN VIEW OF THIS, LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST TRACK REMAINS.// NNNN NNNN