WTPN31 PGTW 222100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL STORM 18W (TAPAH) WARNING NR 016// RMKS/ 1. TROPICAL STORM 18W (TAPAH) WARNING NR 016 01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 221800Z --- NEAR 35.4N 131.5E MOVEMENT PAST SIX HOURS - 050 DEGREES AT 24 KTS POSITION ACCURATE TO WITHIN 050 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 170 NM NORTHEAST QUADRANT 105 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 230 NM NORTHEAST QUADRANT 205 NM SOUTHEAST QUADRANT 190 NM SOUTHWEST QUADRANT 165 NM NORTHWEST QUADRANT REPEAT POSIT: 35.4N 131.5E --- FORECASTS: 12 HRS, VALID AT: 230600Z --- 39.2N 137.0E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 050 KT WINDS - 080 NM NORTHEAST QUADRANT 090 NM SOUTHEAST QUADRANT 080 NM SOUTHWEST QUADRANT 060 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 180 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 180 NM SOUTHWEST QUADRANT 120 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 055 DEG/ 35 KTS --- 24 HRS, VALID AT: 231800Z --- 43.1N 144.7E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 190 NM NORTHEAST QUADRANT 200 NM SOUTHEAST QUADRANT 170 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT --- REMARKS: 222100Z POSITION NEAR 36.3N 132.9E. 22SEP19. TROPICAL STORM 18W (TAPAH), LOCATED APPROXIMATELY 72 NM NORTH-NORTHWEST OF IWAKUNI, JAPAN, HAS TRACKED NORTHEASTWARD AT 24 KNOTS OVER THE PAST SIX HOURS. TS 18W HAS CURRENTLY UNDERGOING EXTRA-TROPICAL TRANSITION (ETT) AND IS RAPIDLY ACCELERATING NORTHEASTWARD WITHIN THE MIDLATITUDE SOUTHWESTERLIES. THE SYSTEM HAS BEGUN TO DISPLAY FRONTAL CHARACTERISTICS IN SATELLITE IMAGERY SUGGESTING THAT IT WILL SOON BE AN EXTRA-TROPICAL SYSTEM. ANIMATED ENHANCED INFRARED SATELLITE DEPICTS A WEAK, ELONGATED LOW-LEVEL CIRCULATION (LLC) WITH DEEP CONVECTION SHEARED TO THE NORTHEAST. A 221711Z AMSR2 36 GHZ MICROWAVE IMAGE SHOWS EXTENSIVE DEEP CONVECTION WITH FRONTAL CHARACTERISTICS HOWEVER, THERE IS NO LCC EVIDENT. THE INITIAL POSITION IS BASED ON THE IR LOOP AND THE JMA RADAR LOOP. THE OVERALL CONFIDENCE IN THE INITIAL POSITION IS LOW DUE TO THE ELONGATED NATURE AND WEAK SIGNATURE OF THE LCC. THE INITIAL INTENSITY OF 55 KNOTS WAS BASED ON AN EARLIER ASCAT IMAGE AND SUPPORTED BY BOTH A PGTW EXTRA-TROPICAL SATELLITE FIX OF T3.5 (55 KNOTS) AND A RECENT SATCON ESTIMATE OF 53 KNOTS. ENVIRONMENTAL CONDITIONS ARE BECOMING INCREASINGLY UNFAVORABLE. THE SYSTEM IS CURRENTLY IN AN AREA OF HIGH (30-40 KNOT) VERTICAL WIND SHEAR AND IS TRACKING OVER COOLER (25-26 CELSIUS) SEA SURFACE TEMPERATURES. THE POOR ENVIRONMENT IS OFFSET BY STRONG POLEWARD OUTFLOW. TS TAPAH IS TRACKING NORTHEASTWARD ALONG THE NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE (STR) LOCATED TO THE SOUTHEAST. THE SYSTEM IS FORECAST TO TRACK TO THE NORTHEAST FOR THE DURATION OF THE FORECAST. THE SYSTEM WILL CONTINUE TO EXPERIENCE A DEGRADING ENVIRONMENT WHICH WILL CAUSE A WEAKENING TREND AS EXTRATROPICAL TRANSITION OCCURS. TS 18W WILL COMPLETE ETT BY TAU 12 AND CONTINUE TO ACCELERATE NORTHEASTWARD, EVENTUALLY MAKING LANDFALL ON NORTHERN HONSHU AND HOKKAIDO AFTER TAU 12. THE SYSTEM IS FORECAST TO REMAIN A STRONG COLD-CORE LOW WITH GALE-FORCE WINDS ANTICIPATED OVER NORTHERN HONSHU. DYNAMIC MODEL GUIDANCE REMAINS IN STRONG AGREEMENT THROUGH TAU 24 LENDING HIGH CONFIDENCE IN THE OFFICIAL JTWC FORECAST TRACK. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 221800Z IS 26 FEET.// NNNN