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本帖最後由 dom 於 2021-4-21 18:02 編輯
底層眼牆建立，JTWC初報上望70節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).//
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