MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING NR 21// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUPER TYPHOON (STY) 26W (MANGKHUT), LOCATED APPROXIMATELY 287 NM NORTH-NORTHWEST OF YAP, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE USING ANIMATED MULTISPECTRAL SATELLITE IMAGERY WHICH SHOWS A ROUND, 26 NM WIDE EYE AND INTENSE RAIN BANDS EXTENDING 200 NM FROM THE CENTER. THE INITIAL INTENSITY OF 140 KNOTS IS CONSISTENT WITH DVORAK ESTIMATES OF T7.0 (140 KTS) FROM PGTW, KNES, AND RJTD. THE ENVIRONMENT IS FAVORABLE WITH LOW (10 KTS) VERTICAL WIND SHEAR (VWS), WARM SEA SURFACE TEMPERATURE (29-30 C), AND EXCELLENT RADIAL OUTFLOW. POLEWARD OUTFLOW IS BEING ENHANCED BY TWO TUTT CELLS, ONE TO THE NORTHWEST AND THE OTHER TO THE EAST. THE CYCLONE IS TRACKING ALONG THE PERIPHERY OF A DEEP-LAYERED EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR) TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS WARNING. B. BY TAU 12, STY 26W WILL HAVE TURNED WEST-NORTHWESTWARD AS THE STR REORIENTS. CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS WILL ALLOW STY 26W TO INTENSIFY SLIGHTLY, REACHING A PEAK INTENSITY OF 145 KTS BY TAU 12 BEFORE THE POLEWARD OUTFLOW BECOMES LESS ENHANCED. BY TAU 72, LAND INTERACTION WITH LUZON WILL HELP REDUCE THE INTENSITY TO 120 KTS. THE INTENSITY FORECAST IS HEDGED TO THE HIGH SIDE OF THE INTENSITY GUIDANCE ENVELOPE AND IS 5 TO 15 KTS ABOVE THE CONSENSUS. THE MODEL TRACK GUIDANCE IS IN EXCELLENT AGREEMENT, WITH JUST OVER 70 NM OF SPREAD BY TAU 72. FOR THAT REASON, CONFIDENCE IS HIGH IN THE JTWC FORECAST TRACK WHICH CLOSELY FOLLOWS THE CONSENSUS. C. AFTER TAU 72, STY 26W WILL CONTINUE TRACKING ALONG THE PERIPHERY OF THE STR ON A NORTHWESTWARD TRACK, MAKING LANDFALL SOUTH OF HONG KONG SHORTLY AFTER TAU 96. LAND INTERACTION, DRY AIR ENTRAINMENT, AND DIMINISHED OUTFLOW WILL ACCELERATE WEAKENING, BRINGING THE INTENSITY TO 70 KTS BY TAU 120. TRACK GUIDANCE REMAINS IN STRONG AGREEMENT, WITH CTCX AND JGSM BEING SLIGHT SOUTHERN OUTLIERS, THEREFORE CONFIDENCE IN THE JTWC FORECAST TRACK, WHICH CLOSELY FOLLOWS THE CONSENSUS, IS HIGH.// NNNN NNNN