SIO: JOBO - Post Tropical

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SIO: JOBO - Post Tropical

#1 Postby cycloneye » Thu Apr 15, 2021 4:37 am

95S INVEST 210415 0600 10.0S 77.0E SHEM 15 0
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Re: SIO: INVEST 95S

#2 Postby TorSkk » Thu Apr 15, 2021 3:21 pm

TROPICAL WEATHER DISCUSSION:
The basin remains in a Near Equatorial Trough pattern (NET) between 50°E-80°E and 05°S-10°S.
The convective activity within this NET is mainly located around the same area of vorticity already
monitored for several days now near 9.8°S and 76.8°E, at the eastern end of the NET.

The latest satellite images show convective puffs only in the southern part of this low and a slight
upper-level divergence circulation, also confirmed by the CIMMS data. The 0444Z scatterometric
swath depicts a lower level circulation center (LLCC), rather wide and elongated from west to east,
with winds around 20 kt maximum in the southwest quadrant.
This vortex will experience unconducive environmental conditions for its development during the
next few days. Indeed, given the current bassin's pattern and the unfavorable tropical wave activity
(dry phase of the MJO), the convergence on the equatorial side will struggle to impose itself,
despite a satisfactory polar trade wind flow. In addition to this constraint, there is also a deficit of
humidity in the middle troposphere and a deep shear that will tend to increase as the days go by.
The latest guidance are rare to suggest a significant deepening for the next few days, with the
exception of the GFS model of 00Z and its ensemble version (the run of 06Z is even less dynamic).
The other guidance do not propose any potential for cyclogenesis.

Thus, during the next 5 days, the risk of developpment of a moderate tropical storm forming
over the basin is considered very low from Monday onwards.
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Re: SIO: INVEST 95S

#3 Postby TorSkk » Fri Apr 16, 2021 5:57 pm

The convective activity is weak over the basin within this dry MJO phase with weak winds all along
the equator without particular pattern. A suspect area is nevertheless present south of Diego Garcia
probably favored by an equatorial Rossby wave.

A weak clockwise circulation is visible today south of Diego-Garcia around 10S/74E at 11Z. The
last analyses gives an estimate of the maximum winds around 15/20kt far from the center in the
southern semicircle.

This vortex will encounter unfavorable environmental conditions for its development over the next
few days as it moves westward. Indeed, given the current basin pattern and the unfavorable wave
activity (dry phase of the MJO), the convergence on the equatorial side will remain inexistent, in
spite of a sufficient trade wind flow on the polar side. By the beginning and middle of next week,
thanks to a small strengthening of the upper level divergence, some deterministic models suggest a
more or less pronounced deepening of the system north of Madagascar. Only a few members of the
European model ensemble forecast propose the formation of a storm. There is no threat to the
inhabited territories during the next 5 days.

During the next 5 days, the risk of development of a moderate tropical storm over the basin is
very low from Tuesday.
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Re: SIO: INVEST 95S

#4 Postby TorSkk » Sat Apr 17, 2021 9:02 am

TROPICAL WEATHER DISCUSSION:
Convection is rather weak over the basin under the influence of a dry MJO phase. With no wind at
the equator, no large-scale configuration is established.
However, an equatorial Rossby wave allow for the survival of a weak and ill-defined clockwise
circulation in the South-West of the Chagos archipelago with 20-kt max winds within the southern
semi-circle. Convection remains ill-organised around this weak system.

As the system drifts westwards over the next days, mid and upper conditions become more
conducive for its development with increasing mid-level moisture and upper divergence. On the
other hand, equatorward low-level convergence remains nonexistent. The last ensemble and
deterministic model runs suggest an increase of the cyclogenesis risk compared to previous
simulations. The strengthening of the trade winds suggested by the models may be sufficient to
constitute a better defined surface circulation and launch a slow cyclogenesis process.

The risk of development of a moderate tropical storm developing North of Madagascar
becomes low Wednesday.
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Re: SIO: INVEST 95S

#5 Postby cycloneye » Sun Apr 18, 2021 6:30 am

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Re: SIO: INVEST 95S

#6 Postby TorSkk » Sun Apr 18, 2021 1:31 pm

TROPICAL WEATHER DISCUSSION:

Convection is rather weak over the basin under the influence of a dry MJO phase. With no wind at
the equator, no large-scale configuration is established.
However, an equatorial Rossby wave allow for the survival of a weak and ill-defined clockwise
circulation in the South-West of the Chagos archipelago. The latest Ascat-B data from 05h30utc,
show maximum winds of about 20kt in the southern semicircle and western quadrant, around a
center located around 10.5S/65E. Convection remains ill-organised around this weak system.

As the system drifts westwards over the next days, mid and upper conditions become more
conducive for its development with increasing mid-level moisture and an increasing altitude
divergence on the polar side as the axis of the jet rises towards the North.. On the other hand,
equatorward low-level convergence remains nonexistent. The last ensemble and deterministic
model runs suggest an increase of the cyclogenesis risk compared to previous simulations from
Wednesday,. The strengthening of the trade winds suggested by the models may be sufficient to
constitute a better defined surface circulation and launch a slow cyclogenesis process.

The risk of development of a moderate tropical storm developing becomes low Wednesday,
North of Madagascar, then to the north of the Comoros archipelago.
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Re: SIO: 16 - Zone of disturbed weather

#7 Postby TorSkk » Mon Apr 19, 2021 8:01 am

TROPICAL WEATHER DISCUSSION:

The basin is in a trade wind configuration east of 70E and has a large area of low pressure west of
70E. The convective activity remains globally weak to moderate over the basin. It is particularly
concentrated west of 70E, north of the Mozambique Channel along the coast of Tanzania and on the
southern side of the large low-pressure area, around 12S/57E.
Within this zone, the last ASCAT swath of 0348UTC does not allow to locate clearly a closed
circulation but notes winds of about 25kt (locally 30kt under convection) in the South sector by
gradient effect, defining the zone of disturbed weather 16-202021 for which the first monitoring
bulletins will be issued at 12UTC. A small closed circulation can be suspected around 10.7S/57.8E.

Zone of disturbed weather 16-20202021:
Position at 09UTC: 10.7S/57.8E
Max 10min wind : 25kt
Motion : West at 13kt
Estimated central pressure : 1007 hPa
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Re: SIO: INVEST 95S

#8 Postby Meow » Mon Apr 19, 2021 8:48 am

The peak is forecasted to be 55 knots, STS.

Image
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Re: SIO: 16- Zone of disturbed weather

#9 Postby TorSkk » Mon Apr 19, 2021 12:35 pm

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 1/16/20202021
1.A ZONE OF DISTURBED WEATHER 16
2.A POSITION 2021/04/19 AT 1200 UTC:
WITHIN 60 NM RADIUS OF POINT 10.7 S / 57.4 E
(TEN DECIMAL SEVEN DEGREES SOUTH AND
FIFTY SEVEN DECIMAL FOUR DEGREES EAST)
MOVEMENT: WEST 11 KT
3.A DVORAK ANALYSIS: 1.5/1.5/S 0.0/24 H
4.A CENTRAL PRESSURE: 1006 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 25 KT
RADIUS OF MAXIMUM WINDS (RMW): NIL
6.A EXTENSION OF WIND BY QUADRANTS (KM):
NIL
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 200 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/20 00 UTC: 11.3 S / 54.2 E, VENT MAX= 025 KT, TROPICAL DISTURBANCE
24H: 2021/04/20 12 UTC: 11.0 S / 51.4 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 0 SE: 370 SW: 315 NW: 0
34 KT NE: 0 SE: 220 SW: 185 NW: 0
36H: 2021/04/21 00 UTC: 10.3 S / 49.1 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
48H: 2021/04/21 12 UTC: 10.0 S / 47.6 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
48 KT NE: 0 SE: 35 SW: 35 NW: 20
60H: 2021/04/22 00 UTC: 10.0 S / 46.4 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
48 KT NE: 0 SE: 35 SW: 35 NW: 20
72H: 2021/04/22 12 UTC: 10.0 S / 45.5 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/23 12 UTC: 10.1 S / 43.5 E, VENT MAX= 025 KT, FILLING UP
120H: 2021/04/24 12 UTC: 9.3 S / 41.1 E, VENT MAX= 020 KT, FILLING UP
2.C ADDITIONAL INFORMATION:
T=CI=1.5+
THE CIRCULATION THAT HAS BEEN MONITORED SINCE LAST WEEK VIA THE RSMC'S
ITCZ BULLETINS, WHILE CIRCULATING NEAR THE CHAGOS, HAS EXPERIENCED A
TEDIOUS DEVELOPMENT DURING ITS WESTWARD TRACK, IN A TOO DRY
ENVIRONMENT LINKED TO THE DRY PHASE OF THE MJO AND WITH A LACK OF
EQUATORWARD CONVERGENCE. HOWEVER, SINCE YESTERDAY SUNDAY AND
ESPECIALLY THIS MONDAY, IT SHOWS SIGNS OF BETTER ORGANIZATION, AS IT
TRACKS OFF THE SOUTHEAST OF AGALEGA. THE CONVECTIVE BANDS CONVERGE
BETTER TOWARDS A MORE DEFINED SURFACE CENTER, WITH DEEP CONVECTION
OF MODERATE INTENSITY ORGANIZED IN A CURVED BAND. THE ASCAT SWATHS OF
THIS MONDAY MORNING INDICATE WINDS OF 25 KT IN THE SOUTHEASTERN
SEMICIRCLE OF THE SYSTEM, SLIGHTLY UP FROM THE PREVIOUS DAYS, BUT WITH A
STRUCTURE THAT REMAINS ASYMMETRIC (SIGNIFICANTLY WEAKER WINDS IN THE
NORTHWESTERN SEMICIRCLE). THE GMI MICROWAVE PASS OF 0715Z SHOWS THE
BEGINNING OF AN ORGANIZATION OF THE SYSTEM.
THERE IS A GOOD AGREEMENT BETWEEN MODELS ABOUT THE SYSTEM'S TRACK
UNTIL WEDNESDAY, WITH A WESTWARD MOVEMENT ON THE NORTHERN SIDE OF
THE LOW TROPOSPHERIC SUBTROPICAL RIDGE, TRACKING IMMEDIATELY SOUTH
OF THE FARQUHAR ATOLL AND OFF NORTHERN MADAGASCAR. FROM WEDNESDAY
AND THURSDAY, WHEN THE SYSTEM WILL REACH THE NORTH OF THE
MOZAMBIQUE CHANNEL AND OFF THE COMOROS, THE STEERING FLOWS BECOME
WEAKER AND THE TRAJECTORY IS MORE UNCERTAIN. IN PARTICULAR, THE MORE
OR LESS IMPORTANT INFLUENCE ON THE NORTH OF THE COMOROS ARCHIPELAGO
REMAINS TO BE SPECIFIED.
ENVIRONMENTAL CONDITIONS ARE RELATIVELY FAVORABLE TO SHORT TERM
DEVELOPMENT : IN THE LOW LAYERS, A TRADEWINDS SURGE IS ONGOING,
REINFORCED TOMORROW BY THE ACCELERATION RELATED TO THE BYPASS OF THE
NORTHERN TIP OF MADAGASCAR, WHICH SHOULD INCREASE THE POLEWARD LOW
LEVEL CONVERGENCE. HOWEVER, DURING THIS TIME, THE EQUATORWARD
CONVERGENCE REMAINS WEAK TO VERY WEAK, WHICH BRINGS UNCERTAINTY ON
THE MORE OR LESS EFFICIENT CONSOLIDATION OF THE LOW'S INNER CORE. ALOFT,
DEEP SHEAR IS WEAK AND SHOULD REMAIN SO FOR THE NEXT FEW DAYS (AROUND
10 KT OR LESS), AND NO INTRUSION OF DRY AIR IN THE MID-TROPOSPHERE SHOULD
INTERFERE WITH CONVECTION NEAR THE CORE OF THE SYSTEM UNTIL
WEDNESDAY. UPPER-TROPOSPHERIC DIVERGENCE IS QUITE GOOD WITH A LIGHT
EQUATORWARD OUTFLOW CHANNEL IN THE SHORT RUN, THEN, FROM MID-WEEK,
AN INCREASE OF UPPER DIVERGENCE ON THE EDGE OF A SUBTROPICAL TROUGH
CIRCULATING FURTHER SOUTH. ON THE OTHER HAND, THE OCEANIC POTENTIAL IS
PRESENT WITH SST AROUND 28-29C AND A GRADUAL INCREASE OF THE DEPTH OF
THE ISO-26C, BECOMING HIGHER IN THE NORTH OF THE MOZAMBIQUE CHANNEL.
THUS, CONDITIONS SEEM TO BE GATHERED FOR MODERATE INTENSIFICATION
UNTIL WEDNESDAY, PROBABLY UNTIL THE STAGE OF A MODERATE TROPICAL
STORM OR EVEN SEVERE TROPICAL STORM. FROM THURSDAY, THE INCREASE OF
THE NORTH TO NORTH-WESTERLY SHEAR ALONG A TROUGH PASSING OVER THE
SOUTH OF MADAGASCAR SHOULD TILT THE CONVECTIVE CORE AND WEAKEN IT
BY ADVECTING DRY AIR. THIS SHOULD LEAD TO THE WEAKENING OF THE SYSTEM
IN THE SECOND PART OF THE WEEK.
THE SMALL SIZE OF THE LOW'S CORE, MAKING IT VERY REACTIVE TO ITS
ENVIRONMENT, INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON THE
PRESENT INTENSITY FORECAST.
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Re: SIO: 16 - Tropical Depression

#10 Postby TorSkk » Tue Apr 20, 2021 3:29 am

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 2/16/20202021
1.A TROPICAL DEPRESSION 16
2.A POSITION 2021/04/20 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 11.0 S / 52.4 E
(ELEVEN DECIMAL ZERO DEGREES SOUTH AND
FIFTY TWO DECIMAL FOUR DEGREES EAST)
MOVEMENT: WEST 12 KT
3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/24 H
4.A CENTRAL PRESSURE: 1003 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
RADIUS OF MAXIMUM WINDS (RMW): 37 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 95 SW: 0 NW: 0
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 200 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/20 18 UTC: 10.6 S / 50.1 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 0 SE: 370 SW: 315 NW: 0
34 KT NE: 0 SE: 220 SW: 185 NW: 0
24H: 2021/04/21 06 UTC: 9.9 S / 48.4 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 0 SE: 220 SW: 185 NW: 0
36H: 2021/04/21 18 UTC: 9.8 S / 47.1 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
48H: 2021/04/22 06 UTC: 9.7 S / 45.9 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 110 SE: 220 SW: 185 NW: 110
48 KT NE: 20 SE: 35 SW: 35 NW: 20
60H: 2021/04/22 18 UTC: 9.6 S / 45.1 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 370 SW: 315 NW: 185
34 KT NE: 75 SE: 220 SW: 185 NW: 75
72H: 2021/04/23 06 UTC: 9.5 S / 44.7 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 0 SE: 370 SW: 315 NW: 0
34 KT NE: 0 SE: 220 SW: 185 NW: 0
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/24 06 UTC: 9.7 S / 43.3 E, VENT MAX= 025 KT, FILLING UP
120H: 2021/04/25 06 UTC: 8.9 S / 40.1 E, VENT MAX= 020 KT, FILLING UP
2.C ADDITIONAL INFORMATION:
T=CI=2.5
THE CIRCULATION THAT HAS BEEN MONITORED SINCE LAST WEEK VIA THE RSMC'S
ITCZ BULLETINS, WHILE CIRCULATING NEAR THE CHAGOS, HAS EXPERIENCED A
TEDIOUS DEVELOPMENT DURING ITS WESTWARD TRACK, IN A TOO DRY
ENVIRONMENT LINKED TO THE DRY PHASE OF THE MJO AND WITH A LACK OF
EQUATORWARD CONVERGENCE. HOWEVER, SINCE YESTERDAY SUNDAY AND
MONDAY, AND ESPECIALLY THE LAST NIGHT, IT SHOWS SIGNS OF BETTER
ORGANIZATION, AS IT TRACKS TOWARDS THE NORTH OF MADAGASCAR THIS
THUESDAY.
THE DEEP CONVECTION OF MODERATE INTENSITY IS STILL QUITE FLUCTUATING,
AND MAINLY PRESENT IN THE NORTH-WEST SEMICIRCLE.
THE LAST ASCAT SWATHS OF THE LAST NIGHT INDICATE WINDS OF 30 KT, VERY
LOCALLY 35KT, IN THE SOUTHEASTERN SEMICIRCLE OF THE SYSTEM, UP FROM THE
PREVIOUS DAYS, BUT WITH A STRUCTURE THAT REMAINS ASYMMETRIC
(SIGNIFICANTLY WEAKER WINDS IN THE NORTHWESTERN SEMICIRCLE). THE SSMIS
MICROWAVE PASS OF 0103Z SHOWS THE BEGINNING OF AN ORGANIZATION OF THE
SYSTEM, WITH THE BEGINNINGS OF A CURVED BAND IN THE NORTHERN
SEMICIRCLE OF THE CIRCULATION.
THERE IS A GOOD AGREEMENT BETWEEN MODELS ABOUT THE SYSTEM'S TRACK
UNTIL WEDNESDAY, WITH A WESTWARD MOVEMENT ON THE NORTHERN SIDE OF
THE LOW TROPOSPHERIC SUBTROPICAL RIDGE, TRACKING IMMEDIATELY SOUTH
OF THE FARQUHAR ATOLL AND OFF NORTHERN MADAGASCAR. FROM WEDNESDAY
AND THURSDAY, WHEN THE SYSTEM WILL REACH THE NORTH OF THE
MOZAMBIQUE CHANNEL AND OFF THE COMOROS, THE STEERING FLOWS BECOME
WEAKER AND THE TRAJECTORY IS MORE UNCERTAIN , MARKING A SLOWDOWN,
EVEN A LOOP ON SOME MODELS IN THE NORTH OF THE COMOROS. IN
CONSEQUENCES, THE MORE OR LESS IMPORTANT INFLUENCE ON THE NORTH OF
THE COMOROS ARCHIPELAGO REMAINS TO BE SPECIFIED.
ENVIRONMENTAL CONDITIONS ARE RELATIVELY FAVORABLE TO SHORT TERM
DEVELOPMENT : IN THE LOW LAYERS, A TRADEWINDS SURGE IS ONGOING,
REINFORCED TOMORROW BY THE ACCELERATION RELATED TO THE BYPASS OF THE
NORTHERN TIP OF MADAGASCAR, WHICH SHOULD INCREASE THE POLEWARD LOW
LEVEL CONVERGENCE. HOWEVER, DURING THIS TIME, THE EQUATORWARD
CONVERGENCE REMAINS WEAK TO VERY WEAK, WHICH BRINGS UNCERTAINTY ON
THE MORE OR LESS EFFICIENT CONSOLIDATION OF THE LOW'S INNER CORE. ALOFT,
DEEP SHEAR IS WEAK AND SHOULD REMAIN SO FOR THE NEXT FEW DAYS (AROUND
10 KT OR LESS), AND NO INTRUSION OF DRY AIR IN THE MID-TROPOSPHERE SHOULD
INTERFERE WITH CONVECTION NEAR THE CORE OF THE SYSTEM UNTIL
WEDNESDAY. UPPER-TROPOSPHERIC DIVERGENCE IS QUITE GOOD WITH A
TEMPORARY LIGHT EQUATORWARD OUTFLOW CHANNEL IN THE SHORT RUN ON
THUESDAY, THEN, FROM MID-WEEK, AN INCREASE OF UPPER DIVERGENCE ON THE
EDGE OF A SUBTROPICAL TROUGH CIRCULATING FURTHER SOUTH. ON THE OTHER
HAND, THE OCEANIC POTENTIAL IS PRESENT WITH SST AROUND 28-29C AND A
GRADUAL INCREASE OF THE DEPTH OF THE ISO-26C, BECOMING HIGHER IN THE
NORTH OF THE MOZAMBIQUE CHANNEL. THUS, CONDITIONS SEEM TO BE
GATHERED FOR MODERATE INTENSIFICATION UNTIL WEDNESDAY, PROBABLY
UNTIL THE STAGE OF A MODERATE TROPICAL STORM OR EVEN SEVERE TROPICAL
STORM. FROM THURSDAY, THE INCREASE OF THE NORTH TO NORTH-WESTERLY
SHEAR ALONG A TROUGH PASSING OVER THE SOUTH OF MADAGASCAR SHOULD
TILT THE CONVECTIVE CORE AND WEAKEN IT BY ADVECTING DRY AIR. THIS
SHOULD LEAD TO THE WEAKENING OF THE SYSTEM IN THE SECOND PART OF THE
WEEK.
THE SMALL SIZE OF THE LOW'S CORE, MAKING IT VERY REACTIVE TO ITS
ENVIRONMENT, INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON THE
PRESENT INTENSITY FORECAST.
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Re: SIO: Tropical Depression 16

#11 Postby TorSkk » Tue Apr 20, 2021 7:16 am

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 3/16/20202021
1.A TROPICAL DEPRESSION 16
2.A POSITION 2021/04/20 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 10.8 S / 51.1 E
(TEN DECIMAL EIGHT DEGREES SOUTH AND
FIFTY ONE DECIMAL ONE DEGREES EAST)
MOVEMENT: WEST 12 KT
3.A DVORAK ANALYSIS: 2.5/2.5/S 0.0/0 H
4.A CENTRAL PRESSURE: 1002 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 30 KT
RADIUS OF MAXIMUM WINDS (RMW): 37 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 0 SE: 165 SW: 165 NW: 0
34 KT NE: 0 SE: 0 SW: 75 NW: 0
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 200 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/21 00 UTC: 10.2 S / 49.4 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 55 SE: 195 SW: 120 NW: 75
34 KT NE: 45 SE: 55 SW: 35 NW: 45
24H: 2021/04/21 12 UTC: 9.9 S / 47.9 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 55 SE: 220 SW: 120 NW: 55
34 KT NE: 45 SE: 75 SW: 45 NW: 45
48 KT NE: 35 SE: 45 SW: 35 NW: 35
36H: 2021/04/22 00 UTC: 9.8 S / 46.6 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 215 SW: 140 NW: 75
34 KT NE: 65 SE: 65 SW: 45 NW: 45
48 KT NE: 35 SE: 45 SW: 35 NW: 35
48H: 2021/04/22 12 UTC: 9.8 S / 45.7 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 205 SW: 140 NW: 55
34 KT NE: 65 SE: 55 SW: 45 NW: 45
48 KT NE: 35 SE: 45 SW: 35 NW: 35
60H: 2021/04/23 00 UTC: 9.6 S / 44.8 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 55 SE: 165 SW: 130 NW: 45
34 KT NE: 45 SE: 30 SW: 35 NW: 30
72H: 2021/04/23 12 UTC: 9.3 S / 44.0 E, VENT MAX= 030 KT, TROPICAL DEPRESSION
28 KT NE: 150 SE: 155 SW: 85 NW: 35
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/24 12 UTC: 9.3 S / 42.1 E, VENT MAX= 025 KT, FILLING UP
120H: 2021/04/25 12 UTC: 8.2 S / 39.3 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.C ADDITIONAL INFORMATION:
T=CI=2.5
THE SYSTEM SHOWS SIGNS OF BETTER ORGANIZATION, AS IT TRACKS TOWARDS
THE NORTH OF MADAGASCAR THIS THUESDAY.
THE LAST ASCAT SWATH OF THIS MORNING INDICATE WINDS OF 30 KT IN THE
SOUTHERN SEMI-CERCLE, MORE LOCALLY 35KT, IN THE SOUTHWESTERN
QUADRANT OF THE SYSTEM, BUT WITH A STRUCTURE THAT REMAINS ASYMMETRIC
(SIGNIFICANTLY WEAKER WINDS IN THE NORTHWESTERN SEMICIRCLE).
THE AMSR2 MICROWAVE PASS OF 0951Z SHOWS THE BEGINNING OF AN
ORGANIZATION OF THE SYSTEM, WITH A BUILDING EYE IN 37GHZ.
THERE IS A GOOD AGREEMENT BETWEEN MODELS ABOUT THE SYSTEM'S TRACK
UNTIL WEDNESDAY, WITH A WESTWARD MOVEMENT ON THE NORTHERN SIDE OF
THE LOW TROPOSPHERIC SUBTROPICAL RIDGE, TRACKING IMMEDIATELY SOUTH
OF THE FARQUHAR ATOLL AND OFF NORTHERN MADAGASCAR. FROM WEDNESDAY
AND THURSDAY, WHEN THE SYSTEM WILL REACH THE NORTH OF THE
MOZAMBIQUE CHANNEL AND OFF THE COMOROS, THE STEERING FLOWS BECOME
WEAKER AND THE TRAJECTORY IS MORE UNCERTAIN , MARKING A SLOWDOWN
ACCORDING TO MOST OF THE MODELS IN THE NORTH OF THE COMOROS. IN
CONSEQUENCES, THE MORE OR LESS IMPORTANT INFLUENCE ON THE NORTH OF
THE COMOROS ARCHIPELAGO REMAINS TO BE SPECIFIED.
ENVIRONMENTAL CONDITIONS ARE RELATIVELY FAVORABLE TO SHORT TERM
DEVELOPMENT : IN THE LOW LAYERS, A TRADEWINDS SURGE IS ONGOING,
REINFORCED TOMORROW BY THE ACCELERATION RELATED TO THE BYPASS OF THE
NORTHERN TIP OF MADAGASCAR, WHICH SHOULD INCREASE THE POLEWARD LOW
LEVEL CONVERGENCE. HOWEVER, DURING THIS TIME, THE EQUATORWARD
CONVERGENCE REMAINS WEAK TO VERY WEAK, WHICH BRINGS UNCERTAINTY ON
THE MORE OR LESS EFFICIENT CONSOLIDATION OF THE LOW'S INNER CORE. ALOFT,
DEEP SHEAR IS WEAK AND SHOULD REMAIN SO FOR THE NEXT FEW DAYS (AROUND
10 KT OR LESS), AND NO INTRUSION OF DRY AIR IN THE MID-TROPOSPHERE SHOULD
INTERFERE WITH CONVECTION NEAR THE CORE OF THE SYSTEM UNTIL
WEDNESDAY. UPPER-TROPOSPHERIC DIVERGENCE IS QUITE GOOD WITH A
TEMPORARY LIGHT EQUATORWARD OUTFLOW CHANNEL IN THE SHORT RUN ON
THUESDAY, THEN, FROM MID-WEEK, AN INCREASE OF UPPER DIVERGENCE ON THE
EDGE OF A SUBTROPICAL TROUGH CIRCULATING FURTHER SOUTH. ON THE OTHER
HAND, THE OCEANIC POTENTIAL IS PRESENT WITH SST AROUND 28-29C AND A
GRADUAL INCREASE OF THE DEPTH OF THE ISO-26C, BECOMING HIGHER IN THE
NORTH OF THE MOZAMBIQUE CHANNEL. THUS, CONDITIONS SEEM TO BE
GATHERED FOR MODERATE INTENSIFICATION UNTIL WEDNESDAY, PROBABLY
UNTIL THE STAGE OF A MODERATE TROPICAL STORM OR EVEN SEVERE TROPICAL
STORM. FROM THURSDAY, THE INCREASE OF THE NORTH-WESTERLY SHEAR AT
MIDDLE LEVEL ALONG A TROUGH PASSING OVER THE SOUTH OF MADAGASCAR
SHOULD TILT THE CONVECTIVE CORE AND WEAKEN IT BY ADVECTING DRY AIR.
THIS SHOULD LEAD TO THE WEAKENING OF THE SYSTEM IN THE SECOND PART OF
THE WEEK.
THE SMALL SIZE OF THE LOW'S CORE, MAKING IT VERY REACTIVE TO ITS
ENVIRONMENT, INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON THE
PRESENT INTENSITY FORECAST
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Re: SIO: JOBO - Moderate Tropical Storm

#12 Postby TorSkk » Tue Apr 20, 2021 3:27 pm

TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 4/16/20202021
1.A MODERATE TROPICAL STORM 16 (JOBO)
2.A POSITION 2021/04/20 AT 1800 UTC:
WITHIN 30 NM RADIUS OF POINT 10.3 S / 49.8 E
(TEN DECIMAL THREE DEGREES SOUTH AND
FORTY NINE DECIMAL EIGHT DEGREES EAST)
MOVEMENT: WEST 11 KT
3.A DVORAK ANALYSIS: 2.5/2.5/D 1.0/24 H
4.A CENTRAL PRESSURE: 999 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 40 KT
RADIUS OF MAXIMUM WINDS (RMW): 24 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 75 SE: 150 SW: 165 NW: 95
34 KT NE: 35 SE: 75 SW: 75 NW: 55
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1010 HPA / 200 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/21 06 UTC: 9.8 S / 48.1 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 65 SE: 100 SW: 110 NW: 85
34 KT NE: 55 SE: 30 SW: 55 NW: 45
48 KT NE: 45 SE: 20 SW: 45 NW: 35
24H: 2021/04/21 18 UTC: 9.7 S / 46.8 E, VENT MAX= 065 KT, TROPICAL CYCLONE
28 KT NE: 65 SE: 100 SW: 100 NW: 110
34 KT NE: 55 SE: 35 SW: 55 NW: 55
48 KT NE: 45 SE: 30 SW: 45 NW: 45
64 KT NE: 20 SE: 20 SW: 20 NW: 35
36H: 2021/04/22 06 UTC: 9.6 S / 45.6 E, VENT MAX= 065 KT, TROPICAL CYCLONE
28 KT NE: 65 SE: 110 SW: 95 NW: 95
34 KT NE: 55 SE: 30 SW: 55 NW: 55
48 KT NE: 45 SE: 20 SW: 45 NW: 45
64 KT NE: 20 SE: 10 SW: 20 NW: 35
48H: 2021/04/22 18 UTC: 9.4 S / 44.5 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 65 SE: 100 SW: 110 NW: 85
34 KT NE: 55 SE: 30 SW: 55 NW: 45
48 KT NE: 45 SE: 20 SW: 45 NW: 35
60H: 2021/04/23 06 UTC: 9.1 S / 43.7 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 45 SE: 85 SW: 85 NW: 85
34 KT NE: 35 SE: 10 SW: 20 NW: 35
72H: 2021/04/23 18 UTC: 9.0 S / 42.8 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 45 SE: 75 SW: 85 NW: 85
34 KT NE: 35 SE: 10 SW: 10 NW: 35
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/24 18 UTC: 8.6 S / 41.1 E, VENT MAX= 025 KT, FILLING UP
120H: 2021/04/25 18 UTC: 7.9 S / 39.4 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.C ADDITIONAL INFORMATION:
T=CI=2.5+
DURING THE LAST 6 HOURS, CONVECTION HAS CLEARLY INTENSIFIED, WITH
STRONG CONVECTIVE BURSTS IN THE VICINITY OF THE SURFACE CENTER (CDO
WITH CLOUD TOPS TEMPERATURES BELOW -80C). RECENT MICROWAVE PASSES
(SSMIS 1532Z) SHOW AN INCREASING ORGANIZATION. WITH WINDS MEASURED AT
30/35 KT THIS MORNING AND TAKING INTO ACCOUNT THE CURRENT
INTENSIFICATION OF THE SYSTEM, WINDS ARE NOW ESTIMATED AT 40 KT AT 1800Z.
THE STAGE OF MODERATE TROPICAL STORM IS THUS CONFIRMED, WITH A SYSTEM
NAMED "JOBO" SINCE 1500Z.
THE WESTWARD TO WEST-NORTHWESTWARD TRACK IS CONFIRMED, WITH A FAIRLY
GOOD AGREEMENT BETWEEN MODELS FOR THE NEXT 48 HOURS. THE SYSTEM IS
MOVING ON THE NORTHERN SIDE OF THE LOW TROPOSPHERIC SUBTROPICAL
RIDGE AND SHOULD PASS NEAR THE SOUTH OF THE OUTER ISLANDS OF THE
SEYCHELLES DURING WEDNESDAY AND THE FOLLOWING NIGHT WHILE
GRADUALLY SLOWING DOWN. FROM THURSDAY ONWARDS, UNCERTAINTY ABOUT
THE TRACK INCREASES WITH STEERING FLOWS BECOMING WEAKER AND THE
TRACK ALSO DEPENDING ON THE INTENSITY THAT THE SYSTEM WILL HAVE AT
THAT TIME. THE PRESENT FORECAST IS BASED ON A MEDIAN SCENARIO BUT WILL
HAVE TO BE CONFIRMED.
ENVIRONMENTAL CONDITIONS REMAIN RELATIVELY FAVORABLE FOR
DEVELOPMENT IN THE SHORT RUN, UNTIL WEDNESDAY NIGHT : IN THE LOW
LAYERS, THE TRADEWINDS SURGE IS REINFORCED BY THE ACCELERATION
RELATED TO THE NORTHERN BYPASS OF MADAGASCAR WHICH INCREASES THE
POLEWARD CONVERGENCE. MEANWHILE, THE EQUATORIAL CONVERGENCE
REMAINS WEAK TO VERY WEAK, WHICH BRINGS UNCERTAINTY ON THE MORE OR
LESS EFFECTIVE CONSOLIDATION OF THE STORM'S CORE. ALOFT, THE DEEP-LAYER
SOUTH-WESTERN SHEAR IS DECREASING AND DOES NOT SEEM TO AFFECT TOO
MUCH THE DEVELOPMENT OF THE SYSTEM IN THE SHORT RUN, IN AN
ENVIRONMENT REMAINING SUFFICIENTLY MOIST AND UNDER GOOD UPPER
DIVERGENCE. ON WEDNESDAY EVENING, THIS UPPER DIVERGENCE WILL EVEN
INCREASE A BIT AT THE EDGE OF A SUBTROPICAL TROUGH CIRCULATING FURTHER
SOUTH WHICH COULD ALLOW THE SYSTEM TO REACH TROPICAL CYCLONE STAGE.
BUT THEN, FROM THURSDAY ONWARDS, A NORTH-WESTERN SHEAR SHOULD SET UP
AND SHOULD ATTACK THE CONVECTIVE CORE BY ADVECTING DRY AIR OVER IT.
THIS SHOULD LEAD TO THE WEAKENING OF THE SYSTEM IN THE SECOND PART OF
THE WEEK.
THE SMALL SIZE OF THE STORM'S CORE MAKING IT VERY REACTIVE TO ITS
ENVIRONMENT INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON THE
PRESENT INTENSITY FORECAST.
POSSIBLE IMPACTS EXPECTED ON THE OUTER ISLANDS OF THE SEYCHELLES
(ASTOVE, COSMOLEDO, ALDABRA) :
-VERY INTENSE RAINFALL THAT COULD EXCEED 150 TO 200 MM IN 24 HOURS.
-STRONG WINDS (DEPENDING ON THE EXACT TRACK OF THE STORM): CYCLONIC
CONDITIONS (GUSTS OVER 150 KM/H) CAN'T BE RULED OUT.
-DANGEROUS SEA CONDITIONS: WAVES EXCEEDING 5 METERS LOCALLY.
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Re: SIO: JOBO - Tropical Storm

#13 Postby Meow » Tue Apr 20, 2021 10:09 pm

Jobo is expected to be TC within 24 hours.

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Re: SIO: JOBO - Severe Tropical Storm

#14 Postby TorSkk » Wed Apr 21, 2021 3:13 am

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 6/16/20202021
1.A SEVERE TROPICAL STORM 16 (JOBO)
2.A POSITION 2021/04/21 AT 0600 UTC:
WITHIN 20 NM RADIUS OF POINT 9.8 S / 48.2 E
(NINE DECIMAL EIGHT DEGREES SOUTH AND
FORTY EIGHT DECIMAL TWO DEGREES EAST)
MOVEMENT: WEST-NORTH-WEST 10 KT
3.A DVORAK ANALYSIS: 3.5/3.5/D 1.0/6 H
4.A CENTRAL PRESSURE: 992 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 55 KT
RADIUS OF MAXIMUM WINDS (RMW): 30 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 95 SE: 185 SW: 185 NW: 95
34 KT NE: 55 SE: 95 SW: 95 NW: 55
48 KT NE: 35 SE: 35 SW: 40 NW: 35
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1012 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/21 18 UTC: 9.5 S / 46.6 E, VENT MAX= 060 KT, SEVERE TROPICAL STORM
28 KT NE: 85 SE: 140 SW: 140 NW: 100
34 KT NE: 75 SE: 55 SW: 75 NW: 95
48 KT NE: 55 SE: 45 SW: 65 NW: 65
24H: 2021/04/22 06 UTC: 9.3 S / 45.3 E, VENT MAX= 070 KT, TROPICAL CYCLONE
28 KT NE: 85 SE: 140 SW: 120 NW: 95
34 KT NE: 75 SE: 55 SW: 65 NW: 85
48 KT NE: 55 SE: 45 SW: 55 NW: 65
64 KT NE: 30 SE: 30 SW: 45 NW: 55
36H: 2021/04/22 18 UTC: 9.2 S / 44.2 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 120 SW: 100 NW: 85
34 KT NE: 65 SE: 55 SW: 65 NW: 65
48 KT NE: 55 SE: 45 SW: 55 NW: 55
48H: 2021/04/23 06 UTC: 9.1 S / 43.2 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
28 KT NE: 85 SE: 100 SW: 100 NW: 85
34 KT NE: 75 SE: 0 SW: 0 NW: 75
60H: 2021/04/23 18 UTC: 8.9 S / 42.0 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 85 SE: 100 SW: 100 NW: 85
34 KT NE: 55 SE: 0 SW: 0 NW: 65
72H: 2021/04/24 06 UTC: 8.6 S / 41.0 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 85 SE: 100 SW: 100 NW: 85
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/25 06 UTC: 7.8 S / 38.8 E, VENT MAX= 025 KT, OVERLAND DEPRESSION
2.C ADDITIONAL INFORMATION:
T=CI=3.5+
DURING THE LAST 6 HOURS, CONVECTION ASSOCIATED WITH STORM JOBO
WRAPPED ON A TIGHT CURVED BAND (MORE THAN A HALF TURN). MICROWAVE
DATA CONFIRM THE DEEPENING WITH A DEFINED EYE IN BOTH 37 AND 89 GHZ (0049
AND 0240Z SSMIS). MOREOVER THIS MORNING SMAP AND SMOS DATA GIVE
RESPECTIVELY 54 AND 50KT I AGREEMENT WITH DVORAK ANALYSIS. INTENSITY IS
RAISED TO 55KT.
THE WESTWARD TO WEST-NORTHWESTWARD TRACK IS CONFIRMED, WITH A FAIRLY
GOOD AGREEMENT BETWEEN MODELS FOR THE NEXT 48 HOURS. THE SYSTEM IS
MOVING ON THE NORTHERN SIDE OF THE LOW TROPOSPHERIC SUBTROPICAL
RIDGE WHILE SLOWING DOWN. AFTER A CLOSE PATH TO COSMOLEDO TODAY, IT IS
EXPECTED TO PASS NEAR ALDABRA TONIGHT. FROM WEDNESDAY AND THE
FOLLOWING NIGHT WHILE GRADUALLY SLOWING DOWN. FROM THURSDAY
ONWARDS, UNCERTAINTY ABOUT THE TRACK INCREASES WITH STEERING FLOWS
BECOMING WEAKER AND THE TRACK ALSO DEPENDING ON THE INTENSITY THAT
THE SYSTEM WILL HAVE AT THAT TIME. SOME DIFFERENCES IN THE TRACK SPEED
ARE FOUND IN THE LATEST GUIDANCE WITH THE LATEST EURO MODELS QUICKER.
THE PRESENT FORECAST IS BASED ON A MEDIAN SCENARIO BUT WILL HAVE TO BE
CONFIRMED.
ENVIRONMENTAL CONDITIONS REMAIN RELATIVELY FAVORABLE FOR
DEVELOPMENT FOR THE NEXT 24H, WITH GOOD UPPER DIVERGENCE AND LOW
SHEAR. GIVEN THIS CONTEXT, JOBO IS EXPECTED TO REACH TROPICAL CYCLONE
STATUS OVERNIGHT. BUT THEN, FROM THURSDAY ONWARDS, UNDER THE
INFLUENCE OF THE TROUGH PASSING FURTHER SOUTH, WESTERLY SHEAR SHOULD
PROGRESSIVELY SET UP, WHICH WILL THEN LEAD TO A GRADUAL WEAKENING OF
THE SMALL CONVECTIVE CORE AND DRY AIR ADVECTION. WEAKENING OF THE
SYSTEM IS THUS EXPECTED IN THE SECOND PART OF THE WEEK. THE SMALL SIZE
OF THE SYSTEM'S CORE MAKING IT VERY REACTIVE TO ITS ENVIRONMENT
INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON THE PRESENT INTENSITY
FORECAST.
POSSIBLE IMPACTS EXPECTED ON THE OUTER ISLANDS OF THE SEYCHELLES
(ASTOVE, COSMOLEDO, ALDABRA) :
-VERY INTENSE RAINFALL THAT COULD EXCEED 200 MM IN 24 HOURS.
-STRONG WINDS (DEPENDING ON THE EXACT TRACK OF THE STORM): CYCLONIC
CONDITIONS (GUSTS OVER 150 KM/H) CAN'T BE RULED OUT FOR ALDABRA.
-DANGEROUS SEA CONDITIONS: WAVES EXCEEDING 6 METERS LOCALLY, STORM
SURGE REACHING 30 TO 40 CM.
BECAUSE OF JOBO'S SMALL SIZE, THE AREA AFFECTED BY SEVERE WEATHER
CONDITIONS IS VERY NARROW, HENCE HIGH UNCERTAINTY ABOUT THESE
IMPACTS.
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Re: SIO: JOBO - Tropical Cyclone

#15 Postby Subtrop » Wed Apr 21, 2021 7:48 am

TC ADVISORY
DTG: 20210421/1232Z
TCAC: REUNION
TC: JOBO
ADVISORY NR: 2021/04
OBS PSN: 21/1200Z S0947 E04736
CB: WI 150NM OF TC CENTRE TOP FL480
MOV: WSW 04KT
INTST CHANGE: INTSF
C: 985HPA
MAX WIND: 65KT
FCST PSN +6 HR: 21/1800Z S0946 E04657
FCST MAX WIND +6 HR: 73KT
FCST PSN +12 HR: 22/0000Z S0945 E04619
FCST MAX WIND +12 HR: 80KT
FCST PSN +18 HR: 22/0600Z S0943 E04541
FCST MAX WIND +18 HR: 73KT
FCST PSN +24 HR: 22/1200Z S0940 E04504
FCST MAX WIND +24 HR: 65KT
RMK: NIL
NXT MSG: 20210421/1800Z
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Re: SIO: JOBO - Tropical Cyclone

#16 Postby TorSkk » Wed Apr 21, 2021 8:41 am

Image


RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 7/16/20202021
1.A TROPICAL CYCLONE 16 (JOBO)
2.A POSITION 2021/04/21 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 9.8 S / 47.6 E
(NINE DECIMAL EIGHT DEGREES SOUTH AND
FORTY SEVEN DECIMAL SIX DEGREES EAST)
MOVEMENT: WEST-SOUTH-WEST 4 KT
3.A DVORAK ANALYSIS: 4.0/4.0/D 0.5/6 H
4.A CENTRAL PRESSURE: 985 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 65 KT
RADIUS OF MAXIMUM WINDS (RMW): 19 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 95 SE: 185 SW: 185 NW: 95
34 KT NE: 55 SE: 95 SW: 95 NW: 55
48 KT NE: 35 SE: 35 SW: 40 NW: 35
64 KT NE: 20 SE: 20 SW: 20 NW: 20
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/22 00 UTC: 9.8 S / 46.3 E, VENT MAX= 080 KT, TROPICAL CYCLONE
28 KT NE: 75 SE: 155 SW: 130 NW: 100
34 KT NE: 65 SE: 65 SW: 55 NW: 75
48 KT NE: 45 SE: 35 SW: 45 NW: 45
64 KT NE: 20 SE: 20 SW: 20 NW: 20
24H: 2021/04/22 12 UTC: 9.7 S / 45.1 E, VENT MAX= 065 KT, TROPICAL CYCLONE
28 KT NE: 75 SE: 130 SW: 110 NW: 95
34 KT NE: 65 SE: 45 SW: 45 NW: 65
48 KT NE: 45 SE: 35 SW: 35 NW: 45
64 KT NE: 20 SE: 20 SW: 20 NW: 20
36H: 2021/04/23 00 UTC: 9.5 S / 43.9 E, VENT MAX= 050 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 85 SW: 95 NW: 75
34 KT NE: 55 SE: 45 SW: 45 NW: 45
48 KT NE: 45 SE: 35 SW: 35 NW: 35
48H: 2021/04/23 12 UTC: 9.3 S / 42.9 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 65 SE: 100 SW: 95 NW: 65
34 KT NE: 45 SE: 35 SW: 35 NW: 35
60H: 2021/04/24 00 UTC: 8.9 S / 42.1 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 0 SE: 55 SW: 55 NW: 55
72H: 2021/04/24 12 UTC: 8.4 S / 41.0 E, VENT MAX= 025 KT, FILLING UP
2.B LONGER-RANGE OUTLOOK:
96H: 2021/04/25 12 UTC: 7.2 S / 38.7 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.C ADDITIONAL INFORMATION:
T=CI=4.0+
DURING THE LAST 6 HOURS, THE CURVED BAND LET PLACE TO A QUITE WELL
DEFINED EYE PATTERN PEAKING AT 10Z. BUT CLOUD TOPS REMAINED RATHER
WARM AND SINCE 10Z, THE CLOUD CONFIGURATION DETERIORATE WITH THE
DECAY OF THE EYE. GMI AND AMSR2 AFTERNOON DATA SHOW THAT THE INNER
CORE CONTRACTED IN COMPARISON WITH LAST NIGHT DATA WITH ALSO A BETTER
EYEWALL, SUGGESTING THAT JOBO INTENSIFIED DURING THIS LAPSE OF TIME. IN
AGREEMENT WITH THE STRONGEST DVORAK ANALYSIS AS WELL AS MICROWAVE
DATA, JOBO IS ANALYZED AS A TROPICAL CYCLONE.
EVEN IF JOBO IS MOVING WESTWARD, IT SLOWED DOWN SIGNIFICANTLY BECAUSE
OF ITS HIGHER STEERING FLOW DUE TO ITS DEEPENING. NEXT THERE IS A FAIRLY
GOOD AGREEMENT BETWEEN MODELS FOR THE MAIN PHILOSOPHY OF THE TRACK
AS THE SYSTEM MOVES ON THE NORTHERN SIDE OF THE LOW TROPOSPHERIC
SUBTROPICAL RIDGE . HOWVEER THERE IS QUITE A SPREAD AMONG THE
GUIDANCE ON THE MOTION SPEED, POTENIALLY EXPLAINED BY THE WEAKER
STEERING FLOWS AND THE DEPENDANCE OF THE MOTION TO ITS INTENSITY. THE
CURRENT FORECAST IS BASED ON A MEDIAN SCENARIO SOMEWHAT SLOWER THAN
LATEST EURO MODELS. AFTER A CLOSE PATH TO COSMOLEDO TODAY, IT IS
EXPECTED TO PASS NEAR ALDABRA TONIGHT OR TOMORROW MORNING.
ENVIRONMENTAL CONDITIONS REMAIN RELATIVELY FAVORABLE FOR
DEVELOPMENT FOR THE NEXT 12H, WITH GOOD UPPER DIVERGENCE AND LOW
SHEAR. TOMORROW THURSDAY AND ONWARDS, UNDER THE INFLUENCE OF THE
TROUGH PASSING FURTHER SOUTH, WESTERLY SHEAR SHOULD PROGRESSIVELY
SET UP, WHICH WILL THEN LEAD TO A GRADUAL WEAKENING OF THE SMALL
CONVECTIVE CORE AND DRY AIR ADVECTION. WEAKENING OF THE SYSTEM IS
THUS EXPECTED IN THE SECOND PART OF THE WEEK. THE SMALL SIZE OF THE
SYSTEM'S CORE MAKE IT VERY RESPONSIVE TO ITS ENVIRONMENT, INDUCING A
HIGHER THAN AVERAGE UNCERTAINTY ON THE PRESENT INTENSITY FORECAST.
POSSIBLE IMPACTS EXPECTED ON THE OUTER ISLANDS OF THE SEYCHELLES
(ASTOVE, COSMOLEDO, ALDABRA) :
-VERY INTENSE RAINFALL THAT COULD EXCEED 200 MM IN 24 HOURS.
-STRONG WINDS (DEPENDING ON THE EXACT TRACK OF THE STORM): CYCLONIC
CONDITIONS (GUSTS OVER 150 KM/H) CAN'T BE RULED OUT
-DANGEROUS SEA CONDITIONS: WAVES EXCEEDING 6 METERS LOCALLY, STORM
SURGE REACHING 30 TO 40 CM.
BECAUSE OF JOBO'S SMALL SIZE, THE AREA AFFECTED BY SEVERE WEATHER
CONDITIONS IS VERY NARROW, HENCE HIGH UNCERTAINTY ABOUT THESE
IMPACTS.
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Re: SIO: JOBO - Tropical Cyclone

#17 Postby TorSkk » Wed Apr 21, 2021 8:54 am

Jobo today

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Re: SIO: JOBO - Tropical Storm

#18 Postby wxman57 » Wed Apr 21, 2021 12:21 pm

Jobo is already weakening. It appears to have peaked between 09Z and 13Z as that eye opened up. Very small storms can spin up quickly and weaken just as quickly. Winds may now be 50-55 kts. Lots of shear in its path, so it may not survive beyond the next 24-36 hrs.
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Re: SIO: JOBO - Severe Tropical Storm

#19 Postby TorSkk » Wed Apr 21, 2021 3:40 pm

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 8/16/20202021
1.A SEVERE TROPICAL STORM 16 (JOBO)
2.A POSITION 2021/04/21 AT 1800 UTC:
WITHIN 20 NM RADIUS OF POINT 9.8 S / 47.0 E
(NINE DECIMAL EIGHT DEGREES SOUTH AND
FORTY SEVEN DECIMAL ZERO DEGREES EAST)
MOVEMENT: WEST 6 KT
3.A DVORAK ANALYSIS: 3.0/4.0/W 1.0/6 H
4.A CENTRAL PRESSURE: 985 HPA
5.A MAX AVERAGE WIND SPEED (10 MN): 60 KT
RADIUS OF MAXIMUM WINDS (RMW): 19 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 95 SE: 335 SW: 220 NW: 95
34 KT NE: 55 SE: 95 SW: 95 NW: 55
48 KT NE: 35 SE: 35 SW: 40 NW: 35
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1009 HPA / 400 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/22 06 UTC: 9.7 S / 45.3 E, VENT MAX= 055 KT, SEVERE TROPICAL STORM
28 KT NE: 75 SE: 155 SW: 150 NW: 100
34 KT NE: 65 SE: 75 SW: 55 NW: 55
48 KT NE: 45 SE: 30 SW: 35 NW: 35
24H: 2021/04/22 18 UTC: 9.5 S / 43.8 E, VENT MAX= 045 KT, MODERATE TROPICAL
STORM
28 KT NE: 140 SE: 120 SW: 85 NW: 110
34 KT NE: 65 SE: 55 SW: 20 NW: 100
36H: 2021/04/23 06 UTC: 9.1 S / 42.6 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 75 SE: 130 SW: 120 NW: 65
34 KT NE: 65 SE: 55 SW: 45 NW: 35
48H: 2021/04/23 18 UTC: 8.4 S / 41.3 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 30 SE: 130 SW: 130 NW: 65
60H: 2021/04/24 06 UTC: 7.8 S / 40.4 E, VENT MAX= 025 KT, FILLING UP
72H: 2021/04/24 18 UTC: 7.4 S / 39.6 E, VENT MAX= 020 KT, REMNANT LOW
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
T=3.0+;CI=4.0+
OVER THE LAST 6 HRS, JOBO'S CLOUD PATTERN CLEARLY DETERIORATED. THE
LAST MODEL ANALYSIS SUGGEST A MODERATE MID-LEVEL NORTH-WESTERLY
SHEAR THAT PUSHED DRY AIR CLOSE TO THE TC CORE. DEEP CONVECTION ONLY
TRIGGERED AGAIN OVER THE SOUTHERN SEMI-CIRCLE IN THE LAST 2 HRS,
PRODUCING AN ILL-DEFINED CDO PATTERN. SSMIS 1328Z AND 1519Z MW IMAGES
CONFIRM THIS DISORGANISATION OF JOBO'S INTERNAL STRUCTURE WITH A FAR
WEAKER CORE THAN ON PREVIOUS IMAGES. ONLY A PSEUDO-EYE REMAINS
VISIBLE ON 85GHZ IMAGERY, BETWEEN TWO CONVECTION BANDS IN THE SOUTH
AND THE NORTH.
IN TERMS OF TRACK, JOBO HAS RESUMED A WESTWARD MOTION ON THE
NORTHERN SIDE OF THE SUBTROPICAL HIGH GEOPOTENTIALS. AS IT WEAKENED,
THE STORM FOUND A STRONGER STEERING FLOW AGAIN, WITHIN THE LOWER
LEVELS OF THE TROPOSPHERE. TOMORROW, JOBO SHOULD CONTINUE WESTWARD
BEFORE A NORTH-WESTWARD TURN LATER ON. THE DISPERSION AROUND THIS
SCENARIO IS MODERATE. SOME TIMING DIFFERENCES REMAIN BETWEEN THE
AVAILABLE MODELS BUT GFS AND IFS ARE NOW IN RATHER GOOD AGREEMENT.
OVER THE NEXT 24H, THE AFOREMENTIONNED NORTH-WESTERLY SHEAR AT THE
MID-LEVELS COULD KEEP ON HINDERING JOBO'S DEVELOPMENT. THE INTENSITY IS
THUS EXPECTED TO REMAINS SOMEWHAT STATIONARY OR EVEN DECREASE A BIT.
FROM TOMORROW EVENING, A WESTERLY SHEAR SHOULD APPEAR AT MID AND
UPPER LEVELS AND TRIGGER A STRONGER WEAKENING. DRY AIR SHOULD ALSO BE
MORE PRESENT FROM FRIDAY EVENING. JOBO'S SMALL SIZE MAKES IT VERY
SENSIBLE TO ITS ENVIRONMENT, THUS INDUCING A GREATER UNCERTAINTY THAN
USUAL ON THE INTENSITY FORECAST.
POSSIBLE IMPACTS EXPECTED ON THE OUTER ISLANDS OF THE SEYCHELLES
(ASTOVE, COSMOLEDO, ALDABRA) :
-VERY INTENSE RAINFALL THAT COULD EXCEED 200 MM IN 24 HOURS.
-STRONG WINDS (DEPENDING ON THE EXACT TRACK OF THE STORM): CYCLONIC
CONDITIONS (GUSTS OVER 150 KM/H) CAN'T BE RULED OUT
-DANGEROUS SEA CONDITIONS: WAVES EXCEEDING 6 METERS LOCALLY, STORM
SURGE REACHING 30 TO 40 CM.
BECAUSE OF JOBO'S SMALL SIZE, THE AREA AFFECTED BY SEVERE WEATHER
CONDITIONS IS VERY NARROW, HENCE HIGH UNCERTAINTY ABOUT THESE
IMPACTS.
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TorSkk
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Re: SIO: JOBO - Moderate Tropical Storm

#20 Postby TorSkk » Thu Apr 22, 2021 9:07 am

RSMC / TROPICAL CYCLONE CENTER / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER: 11/16/20202021
1.A MODERATE TROPICAL STORM 16 (JOBO)
2.A POSITION 2021/04/22 AT 1200 UTC:
WITHIN 20 NM RADIUS OF POINT 9.5 S / 45.0 E
(NINE DECIMAL FIVE DEGREES SOUTH AND
FORTY FIVE DECIMAL ZERO DEGREES EAST)
MOVEMENT: WEST 7 KT
3.A DVORAK ANALYSIS: 2.5/3.0/W 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): 28 KM
6.A EXTENSION OF WIND BY QUADRANTS (KM):
28 KT NE: 85 SE: 130 SW: 75 NW: 75
34 KT NE: 45 SE: 65 SW: 45 NW: 45
7.A FIRST CLOSED ISOBAR (PRESSURE / AVERAGE DIAM): 1012 HPA / 300 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS (WINDS RADII IN KM):
12H: 2021/04/23 00 UTC: 9.2 S / 43.7 E, VENT MAX= 040 KT, MODERATE TROPICAL
STORM
28 KT NE: 55 SE: 100 SW: 95 NW: 65
34 KT NE: 45 SE: 30 SW: 30 NW: 55
24H: 2021/04/23 12 UTC: 8.8 S / 42.4 E, VENT MAX= 035 KT, MODERATE TROPICAL
STORM
28 KT NE: 45 SE: 85 SW: 65 NW: 95
34 KT NE: 35 SE: 10 SW: 10 NW: 45
36H: 2021/04/24 00 UTC: 8.1 S / 41.1 E, VENT MAX= 030 KT, FILLING UP
28 KT NE: 10 SE: 30 SW: 20 NW: 55
48H: 2021/04/24 12 UTC: 7.5 S / 40.3 E, VENT MAX= 025 KT, FILLING UP
60H: 2021/04/25 00 UTC: 6.9 S / 39.6 E, VENT MAX= 020 KT, DISSIPATING
72H: 2021/04/25 12 UTC: 6.2 S / 38.7 E, VENT MAX= 020 KT, OVERLAND DEPRESSION
2.B LONGER-RANGE OUTLOOK:
NIL
2.C ADDITIONAL INFORMATION:
T=2.5;CI=3.0
OVER THE LAST 6 HOURS, THE TOPS HAVE WARMED UP AND THE CONVECTION HAS
CONSIDERABLY DETERIORED, UNDER THE EFFECT OF A MODERATE NORTH TO
NORTH-WEST MID-LEVEL SHEAR, FAVORED BY THE DRIFT OF AN UPPER TROUGH
FURTHER SOUTH. DUE TO THE LACK OF SCATTEROMETRIC DATA AND MICROWAVE
IMAGES, THE DEGREE OF CONFIDENCE IN THE POSITION OF THE JOBO CENTER IS
CONSIDERED MEDIUM. THE LAST DVORAK ANALYSIS LED TO THE DOWNGRADING
OF THE SYSTEM TO A MODERATE TROPICAL STORM.
IN TERMS OF TRACK, JOBO HAS RESUMED A WESTWARD MOTION ON THE
NORTHERN SIDE OF THE SUBTROPICAL HIGH GEOPOTENTIALS.
TOMORROW, JOBO SHOULD THEN START A GRADUAL TURN TOWARDS THE
NORTHWEST, UNDER THE EFFECT OF THE STRENGTHENING OF THE UPPER-LEVEL
RIDGE OVER THE MOZAMBIQUE CHANNEL. ON SATURDAY, WITH THE DECREASE OF
JOBO'S INTENSITY, THE STEERING FLOW IS RESUMED IN LOW LAYERS AND WILL
ORIENTATE THE SYSTEM MORE FRANKLY IN A NORTH-WEST DIRECTION. THE
DISPERSION AROUND THIS SCENARIO REMAINS MODERATE AS THERE ARE STILL
STRONG DIFFERENCES IN TIMING BETWEEN NUMERICAL MODELS.
OVER THE NEXT 24 HOURS, THE NORTHWESTERLY MID-LEVEL WIND SHEAR
SHOULD CONTINUE TO HINDER JOBO DEVELOPMENT. ITS INTENSITY SHOULD
GRADUALLY DECREASE. FROM TOMORROW, THE WESTERLY SHEAR
STRENGTHENING SLIGHTLY, SHOULD BRING MORE DRY AIR IN THE
UPPER-ATMOSPHERE AND START A STRONGER WEAKENING PHASE. THE SMALL SIZE
OF JOBO MAKE IT VERY REACTIVE TO ITS ENVIRONMENT, THUS THE
ENVIRONMENTAL CONDITIONS TO COME FROM SATURDAY SHOULD WEAKEN THE
SYSTEM NOTICEABLY AS IT APPROACHES THE TANZANIAN COAST. HOWEVER, DUE
TO THE SIZE OF JOBO, THIS INDUCES A HIGHER THAN AVERAGE UNCERTAINTY ON
THE PRESENT INTENSITY FORECAST.
IN TERMS OF EXPECTED IMPACTS ON THE OUTER ISLANDS OF THE SEYCHELLES
(ALDABRA, ASTOVE AND COSMOLEDO): THE RISK OF STRONG WINDS AND HEAVY
RAINS DECREASES IN THE NEXT 24HRS, AS JOBO PROGRESSES WESTWARD AND
WEAKENS, BUT INTENSE RAINS OF ABOUT 100 MM ARE STILL POSSIBLE. DURING
THE NEXT 48HRS, THE COMOROS SHOULD BE AFFECTED BY THE PASSAGE OF
PERIPHERAL RAINSTORM BANDS. BECAUSE OF JOBO'S SMALL SIZE, THE AREA
AFFECTED BY SEVERE WEATHER CONDITIONS IS VERY NARROW, HENCE HIGH
UNCERTAINTY ABOUT THESE IMPACTS.
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