SWIO: 94S south of Madagascar (subtropical?)

[Chacor]

VIS:

[P.K.]

WTIO24 FMEE 131222
SECURITE
NEAR GALE WARNING FOR METAREA VII
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTRE/LA REUNION 13/04/2011 AT
1200 UTC.
WARNING NUMBER: 001/09 (SOUTH-WEST INDIAN OCEAN)

10 MINUTES AVERAGE WIND SPEED IN KNOTS (KT)
(WIND GUSTS AT SEA MAY BE ABOUT 40% STRONGER THAN THE AVERAGED WIND).
MINIMUM SEA LEVEL PRESSURE IN HECTOPASCALS (HPA)
(INDICATIVE FIGURE).

NEAR GALE WARNING
BEGINNING OF VALIDITY: WEDNESDAY 13/04/2011 AT 1200 UTC.

PHENOMENON: SUBTROPICAL DEPRESSION 9 1001 HPA
POSITION: WITHIN 20 NM RADIUS OF POINT 27.9S / 48.6E
(TWENTY SEVEN DECIMAL NINE DEGREES SOUTH AND FORTY EIGHT DECIMAL SIX
DEGREES EAST) AT 1200 UTC
MOVEMENT: SOUTH-SOUTH-WEST 6 KT

THREAT AREAS:
SQUALLY WEATHER EXISTS WITHIN A 50 NM RADIUS FROM THE CENTER, EXTENDING
UP TO 150 NM IN THE NORTHWESTERN QUADRANT, UP TO 250 NM IN THE
SOUTHWESTERN QUADRANT AND UP TO 400 NM IN THE SOUTHEASTERN QUADRANT.

GALE FORCE WINDS 35/40 KT AND VERY ROUGH TO HIGH SEAS IN THE SOUTHERN
SEMI-CIRCLE BETWEEN 70 AND 250 NM FROM THE CENTRE WITH GRADIENT EFFECT.
NEAR GALE FORCE WINDS 30 KT AND ROUGH TO VERY ROUGH SEAS WITHIN A 40 NM
RADIUS FROM THE CENTRE, EXTENDING UP TO 50 NM IN THE NORTHWESTERN
QUADRANT, UP TO 250 NM IN THE SOUTHWESTERN QUADRANT AND UP TO 400 NM IN
THE SOUTHEASTERN QUADRANT.
STRONG GUSTS UNDER SQUALLS.

FORECAST POSITION AND INTENSITY:
12H, VALID 2011/04/14 AT 00 UTC:
28.6S / 48.1E, MAX WIND = 30 KT, SUBTROPICAL.
24H, VALID 2011/04/14 AT 12 UTC:
29.9S / 46.8E, MAX WIND = 30 KT, SUBTROPICAL.

OTHER INFORMATIONS:
THE SUBTROPICAL DEPRESSION IS EXPECTED TO KEEP A SOUTH-SOUTHWESTWARD
TRACK WITHIN THE NEXT 24 HOURS AND SHOULD NOT NOTABLY INTENSIFY.

[Extratropical94]

WTIO30 FMEE 131248

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

0.A WARNING NUMBER : 1/9/20102011
1.A SUBTROPICAL DEPRESSION 9

2.A POSITION 2011/04/13 AT 1200 UTC :
WITHIN 20 NM RADIUS OF POINT 27.9S / 48.6E
(TWENTY SEVEN DECIMAL NINE DEGREES SOUTH AND FORTY EIGHT DECIMAL SIX
DEGREES EAST)
MOVEMENT : SOUTH-SOUTH-WEST 6 KT

3.A DVORAK ANALYSIS : /D / H
4.A CENTRAL PRESSURE : 1001 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 30 KT
RADIUS OF MAXIMUM WINDS (RMW) : NIL

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
28 KT NE: 070 SE: 700 SO: 450 NO: 090

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1009 HPA / 550 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: SHALLOW

1.B FORECASTS:
12H: 2011/04/14 00 UTC: 28.6S/48.1E, MAX WIND=030KT, SUBTROPICAL.
24H: 2011/04/14 12 UTC: 29.9S/46.8E, MAX WIND=030KT, SUBTROPICAL.
36H: 2011/04/15 00 UTC: 31.2S/45.9E, MAX WIND=030KT, SUBTROPICAL.
48H: 2011/04/15 12 UTC: 32.7S/45.9E, MAX WIND=030KT, SUBTROPICAL.
60H: 2011/04/16 00 UTC: 34.7S/47.1E, MAX WIND=030KT, BECOMING
EXTRATROPICAL.
72H: 2011/04/16 12 UTC: 37.7S/49.1E, MAX WIND=035KT, EXTRATROPICAL.

2.B LONGER-RANGE OUTLOOK:
96H: 17/04/2011 12 UTC: 41.8S/57.5E, MAX WIND=035KT, EXTRATROPICAL.
120H: 18/04/2011 12 UTC: 43.8S/69.7E, MAX WIND=030KT, EXTRATROPICAL.

2.C ADDITIONAL INFORMATIONS:
NO DVORAK ANALYSIS.
SATELLITE IMAGERY SHOWS A WELL-DEFINED AND PARTIALLY EXPOSED LOW LEVEL
VORTEX. A CONVECTIVE BAND IS PRESENT IN THE SOUTHERN SEMI-CIRCLE OF THE
SYSTEM AND WRAPS FAIRLY CLOSELY FROM THE CENTRE, BUT DIFFICULTY PERSISTS
AT THIS LOCATION. ASCAT SWATH 0557Z IS NOT CENTERED ON THE SYSTEM, BUT IT
IS VERY LIKELY THAT WINDS STRUCTURE IS ASYMMETRIC WITH A LARGE STRONG WINDS
HALF-RING REACHING 35/40 KT WITH GRADIENT EFFECT FROM 70 TO 250 NM FROM
THE CENTRE, AND WEAKER WINDS AT ABOUT 25/30 KT IN THE NORTHERN
SEMI-CIRCLE THAT JUSTIFY THE SUBTROPICAL DEPRESSION STAGE.

THE SYSTEM STILL EVOLVES IN A BAROCLINIC ENVIRONMENT (COLD UPPER LEVEL
LOW AND LOWER THAN USUAL DYNAMICAL TROPOPAUSE) AND GOOD UPPER LEVEL
DIVERGENCE PRESERVES CONVECTION IN THE SOUTHWESTERN EDGE IN PHASIS WITH A
WEAK VERTICAL WINDSHEAR ON THE TROUGH AXIS.

AVAILABLE NWP MODELS FORECAST THAT THE SYSTEM KEEPS A SOUTH-SOUTHWESTWARD
MOVEMENT FOR THE NEXT 36 HOURS AND BEYOND RECURVES SOUTH-EASTWARD. UNTIL
FRIDAY EVENING, UPPER LEVEL CONDITIONS ARE FAVOURABLE AND THE LOW COULD
A LITTLE DEEPEN. DESPITE COLDER SST (25/26C) TOWARD THE SOUTH, IT IS
POSSIBLE THAT THE SUBTROPICAL SYSTEM TEMPORARILY EVOLVES TO A TROPICAL
STRUCTURE IF CONVECTION INCREASES NEAR THE CENTRE AND PERSISTS. ON
AND AFTER 48/60 HOURS, THE SYSTEM SHOULD BEGIN ITS EXTRA-TROPICALIZATION
IN THE WESTERLY CIRCULATION OF THE MID-LATITUDES.

[HURAKAN]

Latest microwave

[HURAKAN]

ZCZC 739
WTIO30 FMEE 141301
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 5/9/20102011
1.A SUBTROPICAL DEPRESSION 9
2.A POSITION 2011/04/14 AT 1200 UTC :
WITHIN 20 NM RADIUS OF POINT 30.5S / 47.7E
(THIRTY DECIMAL FIVE DEGREES SOUTH AND FORTY SEVEN DECIMAL SEVEN
DEGREES
EAST)
MOVEMENT : SOUTH 10 KT
3.A DVORAK ANALYSIS : /D / H
4.A CENTRAL PRESSURE : 998 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 35 KT
RADIUS OF MAXIMUM WINDS (RMW) : NIL
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
28 KT NE: 220 SE: 300 SO: 550 NO: 130
34 KT NE: 130 SE: 150 SO: 200 NO: 090
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 650 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS:
12H: 2011/04/15 00 UTC: 32.1S/47.2E, MAX WIND=035KT, SUBTROPICAL.
24H: 2011/04/15 12 UTC: 33.7S/47.3E, MAX WIND=035KT, EXTRATROPICAL.
36H: 2011/04/16 00 UTC: 35.6S/48.0E, MAX WIND=035KT, EXTRATROPICAL.
48H: 2011/04/16 12 UTC: 38.7S/50.9E, MAX WIND=035KT, EXTRATROPICAL.
60H: 2011/04/17 00 UTC: 40.6S/53.8E, MAX WIND=040KT, EXTRATROPICAL.
72H: 2011/04/17 12 UTC: 41.8S/59.1E, MAX WIND=035KT, EXTRATROPICAL.
2.B LONGER-RANGE OUTLOOK:
96H: 18/04/2011 12 UTC: 44.4S/72.5E, MAX WIND=030KT, EXTRATROPICAL.
2.C ADDITIONAL INFORMATIONS:
SYSTEM HAS SLIGHTLY STRENGTHEN WITHIN THE PAST 6 HOURS. THERE IS NO
EVIDENT IMPROVEMENT IN THE ORGANIZATION OF THE CONVECTIVE ACTIVITY,
EVEN
IF CONVECTION IS CLOSER FROM THE CENTRE ACCORDING TO THE LAST
ANIMATED
SATELLITE PICTURES. ACTUALLY CONVECTION REMAINS FLUCTUATING AND
VERTICAL
EXTENSION IS MO
DERATE. THE LOW LEVEL CIRCULATION CENTRE IS WELL DEFINED.
ACCORDING TO THE ASCAT DATA AT 05.38Z, GALE FORCE WIND 35KT EXISTS
AROUND
MOST OF THE CIRCULATION AT 50NM FAR FROM THE CENTRE. THE RING OF
STRONG
WINDS IS LARGER IN THE SOUTHERN SEMI-CIRCLE DUE TO THE GRADIENT
EFFECT
WITH THE SUBTROPICAL HIGH PRESSURE.
SYSTEM HAS TRACKED SOUTHWARD DURING THE PAST SIX HOURS ON THE WESTREN
EDGE OF A MID-TROPOSPHERIC RIDGE.
SYSTEM TRACKS OVER LOW ENERGETIC POTENTIAL SEAS (25OC) BUT UNDER THE
AXIS
OF A LARGE HIGH TROPOSPHERIC TROUGH SO WITH WEAK UPPER LEVEL
VERTICAL
WIND SHEAR ALOFT. WITHIN THE NEXT 24 HOURS UPPER LEVEL WINDSHEAR IS
EXPECTED TO REMAIN WEAK AND CONVECTION SHOULD LAST. SO INTENSITY IS
NOT
EXPECTED TO CHAN
GE SIGNIFICANTLY WITHIN THE NEXT 24 HOURS.
BEYOND 24TAU, UPPER LEVEL VERTICAL WIND SHEAR IS EXPECTED TO
STRENGTHEN
AND SYSTEM SHOULD BECOME EXTRATROPICAL UNDER THE INFLUENCE OF THE
WESTERLY MID LATITUDES CIRCULATION.=
NNNN

[Reesie]

Interesting - No name has been assigned to 94S despite it forfilling all of the naming criteria for the SWIO.

[P.K.]

Madagascar have obviously decided not to name this. This is why despite the RSMC warning it at 35kts it has no name. It wouldn't be the first unnamed 35kt system.

[Reesie]

Madagascar have obviously decided not to name this. This is why despite the RSMC warning it at 35kts it has no name. It wouldn't be the first unnamed 35kt system.

I realized that, I just found it interesting since Reunion has complained before now of TC's not being named for political reasons.

eg: http://www.wmo.int/pages/prog/www/tcp/d ... IWSATC.pdf - Page 8

[Grifforzer]

40 knots winds

WTIO30 FMEE 150039
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 7/9/20102011
1.A SUBTROPICAL DEPRESSION 9
2.A POSITION 2011/04/15 AT 0000 UTC :
WITHIN 30 NM RADIUS OF POINT 32.2S / 47.0E
(THIRTY TWO DECIMAL TWO DEGREES SOUTH AND FORTY SEVEN DECIMAL ZERO
DEGREES EAST)
MOVEMENT : SOUTH-SOUTH-WEST 9 KT
3.A DVORAK ANALYSIS : / / H
4.A CENTRAL PRESSURE : 995 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 40 KT
RADIUS OF MAXIMUM WINDS (RMW) : 100 KM
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
28 KT NE: 220 SE: 550 SO: 550 NO: 180
34 KT NE: 170 SE: 220 SO: 220 NO: 120
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 740 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS:
12H: 2011/04/15 12 UTC: 33.6S/47.3E, MAX WIND=040KT, SUBTROPICAL.
24H: 2011/04/16 00 UTC: 35.7S/48.9E, MAX WIND=035KT, BECOMING
EXTRATROPICAL.
36H: 2011/04/16 12 UTC: 38.7S/51.5E, MAX WIND=030KT, EXTRATROPICAL.
48H: 2011/04/17 00 UTC: 41.4S/56.1E, MAX WIND=030KT, EXTRATROPICAL.
60H: 2011/04/17 12 UTC: 41.9S/60.3E, MAX WIND=025KT, EXTRATROPICAL.
72H: 2011/04/18 00 UTC: 41.9S/63.6E, MAX WIND=025KT, EXTRATROPICAL.
2.B LONGER-RANGE OUTLOOK:

2.C ADDITIONAL INFORMATIONS:
THE SYSTEM HAS CLEARLY INTENSIFIED FOR THE LAST 6 HOURS WITH
CONVECTION
WRAPPING ALMOST ALL AROUND THE LOW LEVEL CENTRE. NOW THE STRUCTURE OF
THE
SYSTEM IS QUITE SIMILAR TO A TROPICAL STRUCTURE, BUT WITH A RADIUS
OF
MAXIMUM WIND VERY LARGE. ASCAT SWATH 1801Z SHOWS THE WINDS
STRENGTHENING
WITH GREATE
R EXTENSIONS IN THE SOUTHERN SEMI-CIRCLE WITH THE GRADIENT EFFECT. AT
2300Z BUOY 17665 MEASURED A 995 HPA PRESSURE VERY CLOSELY FROM THE
CENTRE
.
YESTERDAY THE SYSTEM HAS REGULARY TRACKED SOUTH-SOUTHWESTWARD ON THE
WESTERN EDGE OF A MID-TROPOSPHERIC RIDGE. IT SHOULD RECURVE SOUTHWARD
THEN SOUTH-EASTWARD WITHIN THE NEXT HOURS TOWARDS A MID-TROPOSPHERIC
TROUGH PASSING IN THE SOUTH.
THE SYSTEM IS TRACKING OVER LOW ENERGETIC POTENTIAL SEAS (24/25C),
BUT
UNDER THE AXIS OF A LARGE HIGH TROPOSPHERIC TROUGH. SO DURING THE
NEXT 12
/18 HOURS, VERTICAL WIND SHEAR SHOULD REMAIN WEAK WITH GOOD UPPER
LEVEL
DIVERGENCE THAT WILL PRESERVE CONVECTION. THUS SYSTEM INTENSITY IS
NOT
EXPECTED TO C
HANGE SIGNIFICANTLY WITHIN THE NEXT 24 HOURS. BEYOND, UPPER LEVEL
VERTICAL WIND SHEAR IS EXPECTED TO STRENGTHEN AND SYSTEM SHOULD
BECOME
EXTRATROPICAL UNDER THE INFLUENCE OF THE WESTERLY MID LATITUDES
CIRCULATION.=

[Crostorm]

[HURAKAN]

ZCZC 586
WTIO30 FMEE 151809
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE TECHNICAL BULLETIN (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 10/9/20102011
1.A SUBTROPICAL DEPRESSION 9
2.A POSITION 2011/04/15 AT 1800 UTC :
WITHIN 20 NM RADIUS OF POINT 34.8S / 48.4E
(THIRTY FOUR DECIMAL EIGHT DEGREES SOUTH AND FORTY EIGHT DECIMAL FOUR
DEGREES EAST)
MOVEMENT : SOUTH-EAST 12 KT
3.A DVORAK ANALYSIS : / / H
4.A CENTRAL PRESSURE : 986 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT
RADIUS OF MAXIMUM WINDS (RMW) : 90 KM
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
28 KT NE: 240 SE: 220 SO: 220 NO: 220
34 KT NE: 165 SE: 150 SO: 150 NO: 165
48 KT NE: 100 SE: 100 SO: 100 NO: 100
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 1018
KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM
1.B FORECASTS:
12H: 2011/04/16 06 UTC: 37.1S/50.1E, MAX WIND=040KT, SUBTROPICAL.
24H: 2011/04/16 18 UTC: 40.4S/53.9E, MAX WIND=040KT, BECOMING
EXTRATROPICAL.
36H: 2011/04/17 06 UTC: 42.6S/60.1E, MAX WIND=040KT, EXTRATROPICAL.
48H: 2011/04/17 18 UTC: 42.3S/66.7E, MAX WIND=030KT, EXTRATROPICAL.
60H: 2011/04/18 06 UTC: 40.3S/72.3E, MAX WIND=025KT, EXTRATROPICAL.
72H: 2011/04/18 18 UTC: 38.7S/77.7E, MAX WIND=025KT, EXTRATROPICAL.
2.B LONGER-RANGE OUTLOOK:
2.C ADDITIONAL INFORMATIONS:
THE CENTER OF THE DEPRESSION WAS LOCATED AT 16Z AT ABOUT 20NM EAST OF
THE
BUOY 14926 WHICH RECORDED 987.4 HPA.
LAST SATELLITE PICTURES DEPICT A VERY WELL DEFINED LOW LEVEL
CIRCULATION
(SSMIS 15.46Z), AND CONVECTION HAS SLIGHTLY STRENGTHEN WITHIN THE
PAST
12HOURS. SO, THE SYSTEME INTENSITY IS MAINTAINED AT 50KT FOR MAX
AVERAGE
WIND SPEED.
SYSTEM IS TRACKING SOUTH-EASTWARD NOW AND HAS ACCELERATED WITHIN THE
PAST
6 HOURS ON THE SOUTH-WESTERN EDGE OF THE SUBTROPICAL RIDGE.
SYSTEM IS TRACKING OVER SST OF 21-22OC AND OVER AN AREA OF TIGHT
GRADIENT
OF SST.
UPPER LEVEL VERTICAL WIND SHEAR SHOULD REMAIN WEAK TONIGHT, SO
STRUCTURE
AND INTENISTY OF THE SYSTEM ARE NOT EXPECTED TO CHANGE A LOT BY 6 TO
12
TAU. BEYOND 12 TO 18 TAU, UPPER LEVEL VERTICAL WIND SHEAR IS EXPECTED
TO
STRENGTHEN RAPIDLY AND WITH SST IN THE RANGE OF 18-19OC, SYSTEM
SHOULD
BECOME RAPI
DLY EXTRATROPICAL. THE WINDFIELD STRUCTURE SHOULD BECOME ASYMETRICAL
WITH
WINDS BY THE ORDER OF GALE FORCE WINDS IN THE NORTHERN SEMI-CIRCLE
UP TO
J+2, ACCORDING TO THE OWN MOVEMENT OF THE SYSTEM AND BY GRADIENT
EFFECT.=
NNNN