SIO: JOBO - Post Tropical

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TorSkk
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Re: SIO: JOBO - Moderate Tropical Storm

#21 Postby TorSkk » Fri Apr 23, 2021 2:20 am

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 14/16/20202021
1.A MODERATE TROPICAL STORM 16 (JOBO)
2.A POSITION 2021/04/23 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 8.9 S / 44.0 E
(EIGHT DECIMAL NINE DEGREES SOUTH AND
FORTY FOUR DECIMAL ZERO DEGREES EAST)
MOVEMENT: WEST-NORTH-WEST 4 KT
3.A DVORAK ANALYSIS: 3.0/3.0/D 0.5/6 H
4.A CENTRAL PRESSURE: 1001 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 150 SW: 150 NW: 0
34 KT NE: 0 SE: 75 SW: 55 NW: 0
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/23 18 UTC: 8.4 S / 42.9 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 45 SE: 150 SW: 150 NW: 75
34 KT NE: 20 SE: 35 SW: 35 NW: 20
24H: 2021/04/24 06 UTC: 7.9 S / 41.8 E, VENT MAX= 030 KT, TROPICAL DEPRESSION
28 KT NE: 85 SE: 185 SW: 185 NW: 55
36H: 2021/04/24 18 UTC: 7.5 S / 40.7 E, VENT MAX= 025 KT, TROPICAL DEPRESSION
48H: 2021/04/25 06 UTC: 7.1 S / 39.5 E, VENT MAX= 025 KT, OVERLAND DEPRESSION
60H: 2021/04/25 18 UTC: 6.6 S / 38.2 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
T=CI=3.0+
DURING THE LAST 6 HOURS, THE DEEP CONVECTION HAS BEEN MAINTAINED WITH
STILL COLD TOPS. IT IS LOCALIZED AT THE CENTER AND EXTENDS A LITTLE MORE
IN THE SOUTHEAST PART OF JOBO, DEFINING A CURVED BAND PATTERN. THE
DVORAK ANALYSIS OF 3.0+ ALLOWS TO ESTIMATE WINDS AROUND 40KT, BUT THE
LAST VISIBLE IMAGES SHOW A HOT SPOT IN THE CENTER OF THE CDO. THIS
CHARACTERISTIC CAN SUGGEST A BEGINNING OF A BOOST IN INTENSITY.
NOT MUCH CHANGE IN TERMS OF TRACK: JOBO CONTINUES ITS
WEST-NORTHWESTWARD TRACK, UNDER THE EFFECT OF THE MID-TROPOSPHERE
RIDGE LOCATED OVER THE CENTER OF THE MOZAMBIQUE CHANNEL AND THE
LOW-LEVEL FLOW OVER THE NORTHERN PART OF THE CHANNEL. THE DISPERSION
AMONG THE LATEST AVAILABLE GUIDANCE REMAINS LOW AND THE PRESENT
FORECAST IS A CONSENSUS OF THE MAIN SCENARIOS. JOBO IS NOW PASSING
BETWEEN 200 AND 300KM NORTH OF THE GREAT COMOROS ARCHIPELAGO. IT WILL
CONTINUE ITS TRACK TOWARDS TANZANIA WHICH IT WILL REACH ON SUNDAY (BE
CAREFUL IN THE PREVIOUS RSMC BULLETIN, AN ERROR WAS MADE ON THE
LANDING DAY). A LANDING IS FORECASTED NEAR DAR ES SALAM ON SUNDAY
MORNING.
AT 6 OR 12H TIME PERIODS, THE WESTERLY SHEAR COULD WEAKEN SLIGHTLY
ALLOWING JOBO TO TEMPORARILY MAINTAIN A MODERATE TROPICAL STORM
INTENSITY. THEREAFTER, THE SHEAR ORIENTING A LITTLE MORE
WEST-SOUTH-WEST THEN SOUTH-WEST IN THE MIDDLE TROPOSPHERE WILL
CONTINUE TO WEAKEN THE SYSTEM BEFORE ITS LANDING. THE SMALL SIZE OF
JOBO INDUCES A LARGER THAN AVERAGE UNCERTAINTY ON THE INTENSITY
FORECAST. IT MAY UNDERGO RAPID VARIATIONS IN INTENSITY.
IN TERMS OF EXPECTED IMPACTS, HEAVY RAINS ARE STILL EXPECTED ON THE
ISLANDS OF THE COMOROS ARCHIPELAGO IN THE MARGIN OF THE STORM THAT
CAN REACH 100 TO 200MM IN 24H, UNTIL THE END OF THE WEEK. GUSTS SHOULD
REMAIN MODEST AROUND 60 KM/H.
FOR TANZANIA, WITH THE WEAKENING OF THE JOBO SYSTEM AT THE LANDING,
THE IMPACTS COULD REMAIN LIMITED IN TERMS OF WIND BUT HEAVY RAINS ARE
EXPECTED AT THE LANDING ZONE.
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Re: SIO: JOBO - Tropical Storm

#22 Postby cycloneye » Fri Apr 23, 2021 7:26 pm

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Re: SIO: JOBO - Post Tropical

#23 Postby wxman57 » Fri Apr 23, 2021 8:39 pm

The official RSMC of the SIO, Meteo-France has declared it a disturbance or remnant low.
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Re: SIO: JOBO - Post Tropical

#24 Postby TorSkk » Sat Apr 24, 2021 4:38 am

WTIO30 FMEE 240623
RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 18/16/20202021
1.A FILLING UP 16 (JOBO)
2.A POSITION 2021/04/24 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 7.6 S / 40.4 E
(SEVEN DECIMAL SIX DEGREES SOUTH AND
FORTY DECIMAL FOUR DEGREES EAST)
MOVEMENT: WEST 10 KT
3.A DVORAK ANALYSIS: 2.0/2.5/W 1.0/12 H
4.A CENTRAL PRESSURE: 1003 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 55 SW: 185 NW: 130
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 500 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/24 18 UTC: 7.1 S / 39.3 E, VENT MAX= 025 KT, OVERLAND DEPRESSION
24H: 2021/04/25 06 UTC: 6.7 S / 38.4 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
T=2.0 CI=2.5
LAST NIGHT, DUE TO MODERATE MID-TROPOSPHERIC SHEAR, THE MAIN CLOUD
MASS DECOUPLED FROM THE LOW-LEVEL CENTER. DURING THE LAST 6 HOURS, AS
THE SYSTEM APPROACHED THE COAST OF TANZANIA, IT BENEFITED FROM AN
INCREASE IN CONVERGENCE IN THE WESTERN PART OF THE CIRCULATION, DEEP
CONVECTION REFORMED OVER THE CENTER, ASSOCIATED WITH STRONG
THUNDERSTORM ACTIVITY. CONSEQUENTLY THE INTENSITY ESTIMATE OF JOBO ISMAINTAINED STATIONARY.
JOBO IS STILL A WEAK SYSTEM SUBJECT TO THE STEERING FLOW OF THE LOWER
LAYERS OF THE TROPOSPHERE. JOBO CONTINUES ITS TRAJECTORY TOWARDS THE
WEST-NORTHWEST. THE DISPERSION IN THE DIFFERENT ENSEMBLE MODELS IS
IMPORTANT IN DIRECTION, NEVERTHELESS JOBO IS APPROACHING THE TANZANIAN
COASTS AND IS CURRENTLY LOCATED 100 KM OFFSHORE. JOBO IS EXPECTED TO
LAND BETWEEN ZANZIBAR AND MOHORO NEXT NIGHT.
IT IS MAINLY A WESTERLY MID-TROPOSPHERE SHEAR THAT WEAKENED JOBO. THIS
ONE IS WEAKENING A BIT, BUT THE HIGH TROPOSPHERE SHEAR IS STRENGTHENING
AT THE SAME TIME, MAINTAINING A WESTERLY STRESS ON THE SYSTEM.
IF THE CONVECTION ASSOCIATED WITH THE SYSTEM BENEFITS TEMPORARILY
FROM THE APPROACH OF THE COASTS, IT IS A WEAK SYSTEM WHICH SHOULD LAND
NEXT NIGHT AND FILL UP QUICKLY WHEN IT ARRIVES ON LAND.
IN TERMS OF EXPECTED IMPACTS AT THE LANDING OF JOBO, THE IMPACTS WILL BE
LIMITED IN TERMS OF WIND BUT HEAVY RAINS ARE EXPECTED IN THE LANDING
AREA BETWEEN ZANZIBAR AND MTWARA, AND EVEN OVER THE NORTH OF
MOZANBIQUE. FROM SUNDAY, WE CAN EXPECT TO HAVE ACCUMULATIONS THAT
CAN REACH 200/300 MM IN 24 HOURS (EVEN VERY LOCALLY 400 TO 500 MM), THAT IS
TO SAY QUANTITIES EQUIVALENT TO THE MONTHLY ACCUMULATION FOR A MONTH
OF APRIL.
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Re: SIO: JOBO - Post Tropical

#25 Postby NXStumpy_Robothing » Sat Apr 24, 2021 5:42 am

With a system as weak and shallow as the remnants of Jobo are, I wouldn't be too surprised to see that upper-troposphere shear have less of an impact than expected, which could open the window for a small amount of restrengthening before landfall. Hopefully, this manages to end up back up to 35kt at landfall and then die like Tropical Storm Don in 2011, so we can get a neat stat out of it and very limited impacts.
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