WTPS31 PGTW 190300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 05P (YASA) WARNING NR 027// RMKS/ 1. TROPICAL CYCLONE 05P (YASA) WARNING NR 027 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 190000Z --- NEAR 21.0S 178.3W MOVEMENT PAST SIX HOURS - 200 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 045 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 045 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 195 NM SOUTHEAST QUADRANT 165 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT REPEAT POSIT: 21.0S 178.3W --- FORECASTS: 12 HRS, VALID AT: 191200Z --- 22.0S 178.6W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 195 DEG/ 06 KTS --- 24 HRS, VALID AT: 200000Z --- 23.2S 179.0W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 210 DEG/ 06 KTS --- 36 HRS, VALID AT: 201200Z --- 24.2S 179.6W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 040 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 100 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT --- REMARKS: 190300Z POSITION NEAR 21.3S 178.4W. 19DEC20. TROPICAL CYCLONE (TC) 05P (YASA), LOCATED APPROXIMATELY 255 NM SOUTHEAST OF SUVA, FIJI, HAS TRACKED SOUTH-SOUTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. TC 05P HAS CONTINUED TO INTERACT WITH A BROAD UPPER-LEVEL TROUGH WITH STRONG (30 KNOTS) VERTICAL WIND SHEAR (VWS), WHICH HAS CONTRIBUTED TO THE STEADY WEAKENING. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN EXPOSED, TIGHTLY-WRAPPED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH LIMITED DEEP CONVECTION SHEARED TO THE SOUTHEAST. THIS IMAGE SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 50 KNOTS BASED ON AN 182044Z ASCAT-B IMAGE SHOWING 45-50 KNOT WINDS OVER THE SOUTH QUADRANT. TC 05P WILL TRACK SOUTHWARD TO SOUTH-SOUTHWESTWARD ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE TO THE NORTHEAST BUT WILL REMAIN EMBEDDED WITHIN THE DEEP UPPER-LEVEL TROUGH WITH INCREASING VWS (40-60 KNOTS) AND COOLING SST VALUES (25C) AFTER TAU 18. TC 05P HAS BEGUN SUBTROPICAL TRANSITION AND IS FORECAST TO COMPLETE SUBTROPICAL TRANSITION BY TAU 36 AS IT TRACKS UNDER THE SUBTROPICAL JET AND THE WIND FIELD EXPANDS AND BECOMES HIGHLY ASYMMETRIC. SLIGHT WEAKENING IS ANTICIPATED, HOWEVER, THE SYSTEM WILL REMAIN A STRONG COLD-CORE LOW WITH 45-50 KNOT WINDS NEAR TAU 36. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH TAU 24. AFTER TAU 24, NUMERICAL MODEL GUIDANCE DIVERGES WITH INCREASING UNCERTAINTY IN THE JTWC FORECAST TRACK DUE TO THE COMPLEX TRANSITION AND MERGER WITH THE UPPER-LEVEL TROUGH / LOW. THEREFORE, THERE IS MODERATE OVERALL CONFIDENCE IN THE JTWC FORECAST TRACK. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 190000Z IS 20 FEET. NEXT WARNINGS AT 190900Z, 191500Z, 192100Z AND 200300Z.// NNNN