SIO : SUBTROPICAL DEPRESSION JOEL (98S)

[HURAKAN]

25/0830 UTC 22.7S 41.9E T1.5/1.5 INVEST -- Southwest Indian

[HURAKAN]

Consensus

[KWT]

Looks like a storm already to me I have to admit, got a very good circulation there!

[HURAKAN]

25/1430 UTC 23.4S 42.5E T2.0/2.0 98S -- Southwest Indian

30 knots

[HURAKAN]

Latest ... JTWC is down, should be back soon

[HURAKAN]

AN AREA OF CONVECTION HAS PERSISTED NEAR 23.7S 43.0E,
APPROXIMATELY 40 NM OFF THE SOUTHWEST COAST OF MADAGASCAR. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY SHOWS A PARTIALLY-EXPOSED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH RELATIVELY SHALLOW CONVECTION SHEARED
TO THE EAST OF THE SYSTEM CENTER. WHILE A 251037Z AQUA MICROWAVE
IMAGE REVEALS BANDING CONVECTION, IT ALSO DEPICTS THE ENTRAINMENT OF
DRY AIR FROM THE NORTHWEST. IN ADDITION, THE TOTAL PRECIPITABLE
WATER PRODUCT SHOWS LITTLE MID-LEVEL MOISTURE IN THE AREA. FINALLY,
THE SYSTEM IS IN AN AREA OF HOSTILE VERTICAL WIND SHEAR (50 TO 60
KNOTS) ASSOCIATED WITH A JET STREAM TO THE SOUTH. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 17 TO 22 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS POOR.

[HURAKAN]

I think we're missing a named system here

[HURAKAN]

26/0230 UTC 24.8S 43.3E T2.0/2.0 98S -- Southwest Indian



Completely missed

[theavocado]

Completely missed

Looks like it's on the poleward side of the STJ to me. Additionally, the shear has to be near 40-50kts, so the circulation is not being sustained by barotropic processes, and most likely is getting support from the jet. Most likely another subtropical system.

[Chacor]

And indeed, we have Subtropical Depression 16R.

[Chacor]

WTIO30 FMEE 260705


RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER : 1/16/20092010
1.A SUBTROPICAL DEPRESSION 16

2.A POSITION 2010/05/26 AT 0600 UTC :
25.2S / 43.5E
(TWENTY FIVE DECIMAL TWO DEGREES SOUTH AND FORTY THREE DECIMAL FIVE
DEGREES EAST)
MOVEMENT : SOUTH-EAST 7 KT

3.A DVORAK ANALYSIS : /D
4.A CENTRAL PRESSURE : 1008 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 25 KT
RADIUS OF MAXIMUM WINDS (RMW) : NIL

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: SE: 030 SO: NO:

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 140 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS:
12H: 2010/05/26 18 UTC: 26.1S/44.2E, MAX WIND=030KT, SUBTROPICAL.
24H: 2010/05/27 06 UTC: 26.4S/44.9E, MAX WIND=030KT, SUBTROPICAL.
36H: 2010/05/27 18 UTC: 26.7S/45.6E, MAX WIND=025KT, BECOMING
EXTRATROPICAL.
48H: 2010/05/28 06 UTC: 27.5S/45.6E, MAX WIND=020KT, FILLING UP.


2.B OTHER INFORMATIONS:
THE CENTER IS NOW LOCATED UNDER THE CONVECTION. THE SYSTEM SHOWS
SUBTROPICAL STRUCTURE, WITH CONVECTION ORGANIZE IN CURVED BAND PATTERN.

THE SYSTEM IS UNDER A SMALL UPPER LEVEL TROUGH SO THE VERTICAL WIND SHEAR
HAS WEAKEN AND IS EXPECTED TO REMAIN WEAK FOR THE NEXT 24 HOURS. SO THE
SYSTEM SHOULD DEEPEN A LITLE OVER SEAS ABOUT 24 DEGRES.
THE SYSTEM IS FORECAST TO TRACK SOUTHEASTWARDS UNDER THE STEERING
INFLUENCE OF THE MIDDLE LEVELS RIDGE PRESENT IN THE EAST AND NORTH-EAST
OF THE SYSTEM.

[HURAKAN]

26/0830 UTC 25.4S 43.4E T2.5/2.5 98S -- Southwest Indian

35 knots

[HURAKAN]

"the eye"

[HURAKAN]

Latest

[Chacor]

Interestingly, it has been named Joël. As far as I am aware this is one of the first times in my memory a subtropical system has been named in the SWIO. Of course, naming here is done by Madagascar and Mauritius, not the RSMC in Réunion.

WTIO30 FMEE 261315 CCA

*************** CORRECTIVE **************
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER : 2/16/20092010
1.A SUBTROPICAL DEPRESSION 16 (JOEL)

2.A POSITION 2010/05/26 AT 1200 UTC :
25.5S / 43.6E
(TWENTY FIVE DECIMAL FIVE DEGREES SOUTH AND FORTY THREE DECIMAL SIX
DEGREES EAST)
MOVEMENT : SOUTH-EAST 5 KT

3.A DVORAK ANALYSIS : /D
4.A CENTRAL PRESSURE : 996 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT
RADIUS OF MAXIMUM WINDS (RMW) : 15 KM

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 060 SE: 080 SO: 070 NO: 060
50 KT NE: 015 SE: 015 SO: 015 NO: 015

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS:
12H: 2010/05/27 00 UTC: 25.9S/44.2E, MAX WIND=060KT , SUBTROPICAL.
24H: 2010/05/27 12 UTC: 26.1S/44.8E, MAX WIND=045KT , SUBTROPICAL.
36H: 2010/05/28 00 UTC: 26.3S/45.3E, MAX WIND=030KT , SUBTROPICAL.
48H: 2010/05/28 12 UTC: 26.7S/45.8E, MAX WIND=025KT , FILLING UP.


2.B OTHER INFORMATIONS:
THE SYSTEM OF SMALL SIZE HAS DEVELOPPED VERY RAPIDLY TO REACH NAMING
STAGE. CONVECTION IS ORGANIZED INTO BANDED EYE PATTERN.
PRESSURE OF THE SYSTEM IS HIGH DUE TO THE SMALL SIZE OF THE SYSTEM AND
HIGH ENVIRONNENTAL PRESSURES.

THE SYSTEM IS UNDER A SMALL UPPER LEVEL TROUGH SO THE VERTICAL WIND SHEAR
HAS WEAKEN AND IS EXPECTED TO REMAIN WEAK FOR THE NEXT 24 TO 36 HOURS.
SO DURING THIS FAVORABLE PERIOD THE SYSTEM SHOULD DEEPEN OVER SEAS ABOUT
24-25 DEGRES BEFORE THE INCREASE OF SOUTHWESTERLY VERTICAL WIND SHEAR
BEYOND.

THE SYSTEM IS FORECAST TO TRACK SOUTHEASTWARDS UNDER THE STEERING
INFLUENCE OF THE MIDDLE LEVELS RIDGE LOCATE IN THE NORTH AND EAST OF
THE SYSTEM.

[HURAKAN]

Interestingly, it has been named Joël. As far as I am aware this is one of the first times in my memory a subtropical system has been named in the SWIO. Of course, naming here is done by Madagascar and Mauritius, not the RSMC in Réunion.

I understand but I don't like how this is classified as a depression when winds are 50 knots. I know it's subtropical but it should be referred as a storm. My opinion.

[HURAKAN]

WOW. The JTWC is sleeping on this!!

[Chacor]

Well, the JTWC doesn't do subtropical cyclones.

[Chacor]

Interestingly, it has been named Joël. As far as I am aware this is one of the first times in my memory a subtropical system has been named in the SWIO. Of course, naming here is done by Madagascar and Mauritius, not the RSMC in Réunion.

I understand but I don't like how this is classified as a depression when winds are 50 knots. I know it's subtropical but it should be referred as a storm. My opinion.

I've been trying to find an updated Tropical Cyclone Operational Plan for the RA I TCC region, but the most recent I can find for it is from 2006. However, there are no provisions made for a "tempête subtropicale" classification; the last time we had a subtropical cyclone with storm-force winds, this term (subtropical storm) was used in the discussion, but not in the official name.

[HURAKAN]

Very interesting system