WTXS31 PGTW 182100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 21S (GUAMBE) WARNING NR 003// RMKS/ 1. TROPICAL CYCLONE 21S (GUAMBE) WARNING NR 003 01 ACTIVE TROPICAL CYCLONE IN SOUTHIO MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 181800Z --- NEAR 23.6S 37.3E MOVEMENT PAST SIX HOURS - 180 DEGREES AT 06 KTS POSITION ACCURATE TO WITHIN 040 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 RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 045 NM SOUTHWEST QUADRANT 065 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT 135 NM SOUTHEAST QUADRANT 095 NM SOUTHWEST QUADRANT 125 NM NORTHWEST QUADRANT REPEAT POSIT: 23.6S 37.3E --- FORECASTS: 12 HRS, VALID AT: 190600Z --- 24.3S 36.8E 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 - 050 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 140 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 140 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 220 DEG/ 04 KTS --- 24 HRS, VALID AT: 191800Z --- 24.9S 36.2E 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 020 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 150 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 205 DEG/ 04 KTS --- 36 HRS, VALID AT: 200600Z --- 25.7S 35.8E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 140 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 090 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 175 DEG/ 06 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 201800Z --- 26.8S 35.9E MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 040 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 120 NM SOUTHWEST QUADRANT 110 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 135 DEG/ 13 KTS --- 72 HRS, VALID AT: 211800Z --- 30.4S 40.0E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING EXTRATROPICAL RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 050 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 130 NM NORTHEAST QUADRANT 160 NM SOUTHEAST QUADRANT 180 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 115 DEG/ 18 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 221800Z --- 33.3S 47.6E MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT WIND RADII VALID OVER OPEN WATER ONLY EXTRATROPICAL RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 070 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT 150 NM SOUTHEAST QUADRANT 180 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT --- REMARKS: 182100Z POSITION NEAR 23.8S 37.2E. 18FEB21. TROPICAL CYCLONE (TC) 21S (GUAMBE), LOCATED APPROXIMATELY 181 NM WEST-SOUTHWEST OF EUROPA ISLAND, HAS TRACKED SOUTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH CONVECTIVE BANDING WRAPPING INTO A DEVELOPING CENTRAL DENSE OVERCAST FEATURE OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 181620Z MHS 89GHZ MICROWAVE IMAGE SHOWS A COMPACT CORE OF DEEP CONVECTION WITH FRAGMENTED BANDING OVER THE EASTERN SEMICIRCLE. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW (5-10 KNOTS) VERTICAL WIND SHEAR (VWS), EXCELLENT EQUATORWARD OUTFLOW, IMPROVING POLEWARD OUTFLOW INTO THE WESTERLIES TO THE SOUTH AND WARM (28-29C) SST VALUES. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS BASED ON THE HIGHER END OF DVORAK INTENSITY ESTIMATES RANGING FROM 3.0-3.5 (45-55 KNOTS) AND AN 181800Z ADT ESTIMATE OF 3.5 (55 KNOTS). AN 181842Z ASCAT-A PARTIAL IMAGE SUPPORTS THE INITIAL POSTION WITH FAIR CONFIDENCE. TC 21S IS FORECAST TO TRACK SOUTHWARD TO SOUTH- SOUTHWESTWARD THROUGH TAU 48 ALONG THE WESTERN PERIPHERY OF A NORTH- SOUTH ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST. AFTER TAU 48, THE SYSTEM WILL RECURVE SOUTHEASTWARD TO EAST-SOUTHEASTWARD AS IT ROUNDS THE STR AND BEGINS TO INTERACT WITH THE MIDLATITUDE WESTERLIES. TC 21S IS FORECAST TO BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 72 AND WILL COMPLETE ETT BY TAU 96 AS IT ACCELERATES WITHIN THE STRONG WESTERLY FLOW AND GAINS FRONTAL CHARACTERISTICS. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT AND SUPPORTS THE JTWC FORECAST TRACK WITH HIGH CONFIDENCE. TC 21S IS EXPECTED TO GRADUALLY INTENSIFY THROUGH TAU 36 WITH A PEAK INTENSITY OF 85 KNOTS AT TAU 36 AND TAU 48. STEADY WEAKENING WILL OCCUR AFTER TAU 48 AS VWS INCREASES AND SST VALUES COOL TO 25-24C. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 181800Z IS 20 FEET. NEXT WARNINGS AT 190900Z AND 192100Z.// NNNN