WTXS31 PGTW 172100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (GUAMBE) WARNING NR 001// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/170251ZFEB2021// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 21S (GUAMBE) WARNING NR 001 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 171800Z --- NEAR 21.9S 37.5E MOVEMENT PAST SIX HOURS - 165 DEGREES AT 03 KTS POSITION ACCURATE TO WITHIN 050 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT 115 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 145 NM NORTHWEST QUADRANT REPEAT POSIT: 21.9S 37.5E --- FORECASTS: 12 HRS, VALID AT: 180600Z --- 22.6S 37.4E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 110 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 215 DEG/ 04 KTS --- 24 HRS, VALID AT: 181800Z --- 23.3S 36.9E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 220 DEG/ 03 KTS --- 36 HRS, VALID AT: 190600Z --- 23.8S 36.4E 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 010 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 220 DEG/ 05 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 191800Z --- 24.5S 35.7E MAX SUSTAINED WINDS - 080 KT, GUSTS 100 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 050 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 130 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 180 DEG/ 05 KTS --- 72 HRS, VALID AT: 201800Z --- 26.6S 35.6E MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 000 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 120 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 100 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 135 DEG/ 07 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 211800Z --- 28.6S 38.0E MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 190 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 115 DEG/ 13 KTS --- 120 HRS, VALID AT: 221800Z --- 30.7S 43.3E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 130 NM NORTHWEST QUADRANT --- REMARKS: 172100Z POSITION NEAR 22.1S 37.5E. 17FEB21. TROPICAL CYCLONE (TC) 21S (GUAMBE), LOCATED APPROXIMATELY 151 NM WEST OF EUROPA ISLAND, HAS TRACKED SOUTH-SOUTHEASTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH A DEVELOPING CENTRAL DENSE OVERCAST FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 171837Z MHS 89GHZ MICROWAVE IMAGE SHOWS DEEP CONVECTIVE BANDING OVER THE NORTHERN SEMICIRCLE WRAPPING INTO THE LLCC. UPPER- LEVEL ANALYSIS INDICATES MARGINALLY-FAVORABLE CONDITIONS WITH LOW TO MODERATE VERTICAL WIND SHEAR OFFSET BY NEAR RADIAL OUTFLOW AND WARM (29-30C) SST VALUES. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS BASED ON A 171838Z ASCAT-B IMAGE SHOWING A SWATH OF 40-45 KNOT WINDS OVER THE EASTERN SEMICIRCLE. ADDITIONALLY, A 171827Z SCATSAT IMAGE SHOWED 43-47 KNOTS OVER THE EASTERN QUADRANT. DVORAK CURRENT INTENSITY ESTIMATES RANGE FROM 2.5-3.0 (35-45 KNOTS). THERE IS SOME UNCERTAINTY IN THE INITIAL POSITION DUE TO THE PRESENCE OF DEEP CONVECTION OVER THE LLCC AND THE LACK OF HIGH-RESOLUTION MICROWAVE IMAGERY AT THIS TIME. TC 21S IS FORECAST TO TRACK SOUTHWARD TO SOUTH- SOUTHWESTWARD THROUGH TAU 72 ALONG THE WESTERN PERIPHERY OF A NORTH- SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. AFTER TAU 72, THE SYSTEM WILL RECURVE SOUTHEASTWARD TO EAST-SOUTHEASTWARD AS IT ROUNDS THE STR AND BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES. EXTRA-TROPICAL TRANSITION WILL COMMENCE NEAR TAU 96 AND CONTINUE AT TAU 120 AS THE SYSTEM TRACKS WITHIN THE WESTERLY FLOW ALONG THE NORTHERN EDGE OF THE BAROCLINIC ZONE. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT AND SUPPORTS THE JTWC FORECAST TRACK WITH MODERATE CONFIDENCE. TC 21S IS EXPECTED TO GRADUALLY INTENSIFY THROUGH TAU 48 WITH A PEAK INTENSITY OF 80 KNOTS AT TAU 48. STEADY WEAKENING WILL OCCUR AFTER TAU 72 AS VWS INCREASES AND SST VALUES COOL TO 26-27C. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 171800Z IS 16 FEET. NEXT WARNINGS AT 180900Z AND 182100Z. 2. THIS CANCELS AND SUPERSEDES REF A (WTXS21 PGTW 170300).// NNNN