WTXS31 PGTW 210300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 29S (JOBO) WARNING NR 001// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/200821ZAPR2021// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. TROPICAL CYCLONE 29S (JOBO) 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: 210000Z --- NEAR 10.0S 48.8E MOVEMENT PAST SIX HOURS - 285 DEGREES AT 08 KTS POSITION ACCURATE TO WITHIN 030 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 - 000 NM NORTHEAST QUADRANT 035 NM SOUTHEAST QUADRANT 035 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT REPEAT POSIT: 10.0S 48.8E --- FORECASTS: 12 HRS, VALID AT: 211200Z --- 9.7S 47.3E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 040 NM SOUTHEAST QUADRANT 050 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 275 DEG/ 08 KTS --- 24 HRS, VALID AT: 220000Z --- 9.5S 45.7E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 050 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 280 DEG/ 05 KTS --- 36 HRS, VALID AT: 221200Z --- 9.3S 44.7E MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 064 KT WINDS - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 48 HR POSIT: 285 DEG/ 04 KTS --- EXTENDED OUTLOOK: 48 HRS, VALID AT: 230000Z --- 9.1S 43.9E MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 025 NM SOUTHEAST QUADRANT 025 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 060 NM SOUTHWEST QUADRANT 020 NM NORTHWEST QUADRANT VECTOR TO 72 HR POSIT: 285 DEG/ 04 KTS --- 72 HRS, VALID AT: 240000Z --- 8.7S 42.3E MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 96 HR POSIT: 280 DEG/ 05 KTS --- LONG RANGE OUTLOOK: --- 96 HRS, VALID AT: 250000Z --- 8.4S 40.2E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY RADIUS OF 050 KT WINDS - 000 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 000 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 020 NM NORTHEAST QUADRANT 070 NM SOUTHEAST QUADRANT 070 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT VECTOR TO 120 HR POSIT: 270 DEG/ 06 KTS --- 120 HRS, VALID AT: 260000Z --- 8.5S 37.7E MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND --- REMARKS: 210300Z POSITION NEAR 9.9S 48.4E. 21APR21. TROPICAL CYCLONE 29S (JOBO), LOCATED APPROXIMATELY 539 NM NORTH OF ANTANANARIVO, MADAGASCAR, HAS TRACKED WEST-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ENHANCED INFRARED SATELLITE IMAGERY SHOWS A SMALL, RAPIDLY DEVELOPING CYCLONE, WITH A CURVED BAND OF CONVECTION WITH CLOUD TOPS COLDER THAN -80C NEARLY ENCIRCLING THE LOW-LEVEL CENTER. A 210052Z SSMIS 91GHZ MICROWAVE IMAGE SHOWED A RING OF DEEP CONVECTION ABOUT 60 NM IN DIAMETER WRAPPING AROUND 80% OF THE CIRCULATION, FORMING A WELL-DEFINED EYE- LIKE FEATURE. THE INITIAL INTENSITY IS SET AT 45 KTS, PERHAPS CONSERVATIVELY, BASED ON A 210230Z PGTW FIX OF 3.0. CONFIDENCE IN THIS ESTIMATE IS LOW DUE TO THE RAPIDLY DEVELOPING NATURE OF THE SYSTEM. THE LARGE-SCALE ENVIRONMENT HAS CONSISTED OF LIGHT-MODERATE WESTERLY VERTICAL WIND SHEAR (VWS) OF 15-20 KTS FOR THE PAST 12 HOURS, BUT EXPANDING CIRRUS OUTFLOW IN THE WESTERN SEMICIRCLE SUGGESTS THAT THIS SHEAR IS DECREASING. JOBO IS BEING STEERED WEST- NORTHWESTWARD BY A BELT OF LOW-LEVEL EASTERLIES EQUATORWARD OF THE SUBTROPICAL RIDGE. THIS MOTION WILL CARRY JOBO BENEATH AN UPPER- LEVEL ANTICYCLONE SEEN IN WATER VAPOR SATELLITE IMAGERY OFFSHORE OF TANZANIA DURING THE NEXT 12-18 HOURS, WHERE VWS IS EXPECTED TO DECREASE TO 10-15 KTS. COMBINED WITH WARM SEA SURFACE TEMPERATURES OF 29C, THIS ENVIRONMENT IS EXPECTED TO FAVOR RAPID INTENSIFICATION IN THE NEAR TERM, TO AROUND 70 KTS AT 24 HOURS, SUPPORTED BY RECENT HWRF MODEL FORECASTS THAT HAVE ACCURATELY DEPICTED THE COMPACT NATURE OF THE VORTEX. IN 24-36 HOURS, AN UPPER-LEVEL TROUGH IN THE SUBTROPICAL JET OVER MOZAMBIQUE WILL APPROACH JOBO FROM THE WEST, INCREASING VWS BACK TO AROUND 20 KTS. THIS SHOULD ARREST THE INTENSIFICATION TREND, AND THE SMALL CYCLONE, BEING PARTICULARLY SUSCEPTIBLE TO MODERATE SHEAR, IS EXPECTED TO WEAKEN BETWEEN 36 AND 72 HOURS. SLOWING OF FORWARD MOTION IS ALSO EXPECTED AS LOW-LEVEL EASTERLIES BECOME OFFSET BY THE UPPER-LEVEL WESTERLY FLOW. AFTER 72 HOURS, THE AFOREMENTIONED UPPER-LEVEL TROUGH MOVES AWAY TO THE SOUTHEAST, POSSIBLY ALLOWING A PERIOD OF LIGHTER SHEAR ONCE AGAIN AS JOBO APPROACHES THE TANZANIAN COASTLINE. THE FORECAST SHOWS THE POSSIBILITY OF SOME REINTENSIFICATION BEFORE LANDFALL JUST AFTER 96 HOURS, FOLLOWED BY DISSIPATION INLAND. CONFIDENCE IN THE INTENSITY FORECAST IS LOW, GIVEN THE SUSCEPTIBILITY OF COMPACT CYCLONES TO QUICK UPS AND DOWNS IN INTENSITY. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 210000Z IS 12 FEET. NEXT WARNINGS AT 211500Z AND 220300Z. 2. THIS CANCELS AND SUPERSEDES REF A (WTXS21 PGTW 200830).// NNNN