WTPS31 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 05P (YASA) WARNING NR 023// RMKS/ 1. TROPICAL CYCLONE 05P (YASA) WARNING NR 023 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 180000Z --- NEAR 18.3S 178.9W MOVEMENT PAST SIX HOURS - 130 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 020 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 055 NM SOUTHWEST QUADRANT 055 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 165 NM SOUTHEAST QUADRANT 155 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT REPEAT POSIT: 18.3S 178.9W --- FORECASTS: 12 HRS, VALID AT: 181200Z --- 19.5S 177.8W MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 020 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 170 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 155 DEG/ 07 KTS --- 24 HRS, VALID AT: 190000Z --- 20.8S 177.1W MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 080 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 175 DEG/ 06 KTS --- 36 HRS, VALID AT: 191200Z --- 21.9S 177.0W MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 020 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 185 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 200000Z --- 22.7S 177.1W MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 010 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 010 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 195 DEG/ 03 KTS --- 72 HRS, VALID AT: 210000Z --- 23.7S 177.4W MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT --- REMARKS: 180300Z POSITION NEAR 18.6S 178.6W. 18DEC20. TROPICAL CYCLONE (TC) 05P (YASA), LOCATED APPROXIMATELY 154 NM EAST OF SUVA, FIJI, HAS TRACKED SOUTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. TC 05P HAS BEGUN TO INTERACT WITH AN APPROACHING UPPER-LEVEL TROUGH WITH INCREASING (20-25 KNOTS) VERTICAL WIND SHEAR (VWS), WHICH HAS CONTRIBUTED TO A RAPID WEAKENING TREND. HOWEVER, DEEP CONVECTIVE BANDING HAS REFORMED OVER THE WESTERN SEMICIRCLE, WRAPPING INTO A TIGHTLY-WRAPPED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 75 KNOTS BASED ON THE LOWER END OF DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 4.5 TO 5.0 (77-90 KNOTS) AND AN ADT CURRENT INTENSITY ESTIMATE OF 4.6 (77-80 KNOTS). TC 05P WILL TRACK SOUTHEASTWARD TO SOUTHWARD ALONG THE PERIPHERY OF THE SUBTROPICAL RIDGE TO THE NORTHEAST BUT WILL REMAIN EMBEDDED WITHIN THE DEEP UPPER-LEVEL TROUGH WITH MODERATE TO STRONG VWS OFFSET SLIGHTLY BY ENHANCED POLEWARD OUTFLOW, WHICH WILL LEAD TO A STEADY WEAKENING TREND. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH TAU 24. TC 05P WILL BEGIN SUBTROPICAL TRANSITION NEAR TAU 24 AS IT APPROACHES THE SUBTROPICAL JET WITH VWS INCREASING TO 40 TO 60 KNOTS AND SST VALUES COOLING TO 25C BY TAU 48. TC 05P IS FORECAST TO COMPLETE SUBTROPICAL TRANSITION BY TAU 72 AS IT TRACKS UNDER THE AFOREMENTIONED JET AND THE WIND FIELD EXPANDS AND BECOMES HIGHLY ASYMMETRIC. 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 180000Z IS 28 FEET. NEXT WARNINGS AT 180900Z, 181500Z, 182100Z AND 190300Z.// NNNN