WTPN32 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL STORM 23W (NAMTHEUN) WARNING NR 031// RMKS/ 1. TROPICAL STORM 23W (NAMTHEUN) WARNING NR 031 01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 171200Z --- NEAR 36.1N 167.1E MOVEMENT PAST SIX HOURS - 350 DEGREES AT 13 KTS POSITION ACCURATE TO WITHIN 030 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 36.1N 167.1E --- FORECASTS: 12 HRS, VALID AT: 180000Z --- 39.3N 169.0E MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 080 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 050 DEG/ 27 KTS --- 24 HRS, VALID AT: 181200Z --- 42.5N 174.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL --- REMARKS: 171500Z POSITION NEAR 36.9N 167.6E. 17OCT21. TROPICAL STORM (TS) 23W (NAMTHEUN), LOCATED APPROXIMATELY 984 NM NORTHEAST OF MINAMI TORI SHIMA, HAS TRACKED NORTHWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ALTHOUGH DEEP CONVECTION IS SPARSE, ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS STRONG MID- LEVEL TURNING ASSOCIATED WITH AN UPPER-LEVEL TROUGH POSITIONED OVER THE PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION. A 171017Z METOP-B MHS 89GHZ MICROWAVE IMAGE DEPICTS SHALLOW BANDING WRAPPING INTO A DEFINED CENTER WITH EXTENSIVE DRY AIR SURROUNDING THE SYSTEM AND ENTRAINING INTO THE SOUTH QUADRANT. A 171020Z ASCAT-B BULLSEYE IMAGE SHOWS AN ASYMMETRIC WIND FIELD SURROUNDING A DEFINED CENTER WITH 30- 35 KNOT WINDS OVER THE EAST AND NORTH QUADRANTS. THE INITIAL POSITION AND INTENSITY ARE BASED ON THE ASCAT IMAGE WITH HIGH CONFIDENCE. BASED ON THE AFOREMENTIONED IMAGERY, TS 23W HAS MAINTAINED SUBTROPICAL CHARACTERISTICS BUT IS ALSO INTERACTING WITH THE BAROCLINIC ZONE JUST TO THE NORTH WITH COLD AIR STRATOCUMULUS ADVECTING OVER THE WESTERN SEMICIRCLE. THUS, EXTRA-TROPICAL TRANSITION HAS COMMENCED AND IS EXPECTED TO COMPLETE WITHIN THE NEXT 12 HOURS AS THE SYSTEM ACCELERATES NORTH-NORTHEASTWARD TO NORTHEASTWARD. TS 23W WILL GAIN FRONTAL CHARACTERISTICS AND APPROACH THE MIDLATITUDE JET BY TAU 12. OVERALL, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS. 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 171200Z IS 17 FEET.// NNNN