SWIndian: ex-Subtropical Depression 15R

[Chacor]

WTIO24 FMEE 120013
SECURITE
GALE WARNING FOR METAREA VII
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTRE/LA REUNION 12/04/2007 AT
0000 UTC.
WARNING NUMBER: 002/15 (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).

GALE WARNING
BEGINNING OF VALIDITY: THURSDAY 12/04/2007 AT 0000 UTC.

PHENOMENON: SUBTROPICAL DEPRESSION 15 998 HPA
POSITION: 32.6S / 41.6E
(THIRTY TWO DECIMAL SIX DEGREES SOUTH AND FORTY ONE DECIMAL SIX DEGREES
EAST) AT 0000 UTC
MOVEMENT: SOUTH-EAST 18 KT

THREAT AREAS:
SQUALLY WEATHER EXISTS LOCALLY WITHIN 150 NM FROM THE CENTER, EXTENDING
UP TO 500 NM IN THE SOUTHEASTERN SEMI-CIRCLE.

GALE FORCE WINDS 35/40 KT AND VERY ROUGH TO HIGH SEAS WITHIN 50 NM RADIUS
FROM THE CENTER.
NEAR GALE FORCE WINDS AND ROUGH TO VERY ROUGH SEAS WITHIN 80 NM FROM THE
CENTER, EXTENDING LOCALLY UP TO 140 NM IN THE SOUTHEASTERN SECTOR.
SRONG GUSTS UNDER SQUALLS.

FORECAST POSITION AND INTENSITY:
12H, VALID 2007/04/12 AT 12 UTC:
37.1S / 45.4E, MAX WIND = 40 KT, EXTRATROPICAL.
24H, VALID 2007/04/13 AT 00 UTC:
42.3S / 51.9E, MAX WIND = 40 KT, EXTRATROPICAL.

OTHER INFORMATIONS:
THIS SYSTEM IS NOW LOCATED OVER COOL SST (NEAR 22°C) AND IS EVACUATING
RAPIDLY SOUTHEASTWARDS, WHERE THE ENVIRONMENT IS STRONGLY NORTHWESTERLY
WINDSHEARED. IN THOSE CONDITIONS, THE ACTUAL EXTRATROPICAL TRANSITION
WILL SOON BE COMPLETED.

THE LOW LEVEL CLOCKWISE CIRCULATION IS ASYMMETRICAL AND THE STRONG WIND
EXTENSION IS MORE IMPORTANT IN THE SOUTHEASTERN DUE TO THE GRADIENT WITH
HIGH PRESSURES. THE SYSTEM IS EXPECTED TO EVACUATE RAPIDLY SOUTHEASTWARDS.

[HURAKAN]

214
WTIO30 FMEE 111207

RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)

0.A WARNING NUMBER : 1/15/20062007
1.A SUBTROPICAL DEPRESSION 15

2.A POSITION 2007/04/11 AT 1200 UTC :
WITHIN 20 NM RADIUS OF POINT 29.6S / 39.6E
(TWENTY NINE DECIMAL SIX DEGREES SOUTH AND THIRTY NINE DECIMAL SIX
DEGREES EAST)

3.A DVORAK ANALYSIS : /
4.A CENTRAL PRESSURE : 998 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 45 KT

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 220 SE: 440 SO: 270 NO: 160

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1010 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: MEDIUM

1.B FORECASTS:
12H: 2007/04/12 00 UTC: 32.3S/41.3E, MAX WIND=045KT, SUBTROPICAL.
24H: 2007/04/12 12 UTC: 35.5S/43.7E, MAX WIND=040KT, BECOMING
EXTRATROPICAL.
36H: 2007/04/13 00 UTC: 38.9S/47.9E, MAX WIND=040KT, EXTRATROPICAL.
48H: 2007/04/13 12 UTC: 42.3S/53.8E, MAX WIND=040KT, EXTRATROPICAL.


2.B OTHER INFORMATIONS:
TAKING BENEFIT OF A SLIGHT DECREASE OF THE VERTICAL WIND SHEAR, THE
SYSTEM IS NOW ORGANIZED AS A SUBTROPICAL DEPRESSION. AS DEPICTED BY
THE
QUIKSCAT DATA, THE LOW LEVEL CLOCKWISE CIRCULATION IS NOT SYMMETRICAL
AND
THE STRONG WINDS EXTENSION IS RATHER WIDE, ESPECIALLY IN THE
SOUTHERN
SEMI-CIRCLE. THE
ASSOCIATED CONVECTIVE ACTIVITY IS WEAK (SST REACHES HARDLY 25
DEGREES)
AND SHOWS AN VERY ASYMMETRICAL PATTERN.
THE SYSTEM IS EXPECTED TO KEEP ON TRACKING SOUTHWARDS AND THEN
SOUTHEASTWARDS, AND TO FOLLOW SHORTLY AN EXTRA-TROPICAL TRANSITION
DUE TO
TYE INCREASING VERTICAL WIND SHEAR.

NEXT WARNING : APRIL 12 AT 0000Z.

[Chacor]

What I don't get is them issuing advisories when they forecast for it to become extratropical so quickly. And this looks like ex-Jaya.

[Chacor]

Oh, and a little clarification: a "subtropical depression" refers to any subtropical cyclone in this basin. The term "subtropical storm" is not used. Its current intensity, at 40 kt, means that if this was fully-tropical, it would be named.

[senorpepr]

Oh, and a little clarification: a "subtropical depression" refers to any subtropical cyclone in this basin. The term "subtropical storm" is not used. Its current intensity, at 40 kt, means that if this was fully-tropical, it would be named.

Thanks for pointing that out!

[Chacor]

By the way, this system is not related to the former Intense TC Jaya. I emailed MF to ask, and it's a different low.

[Chacor]

Extratropical now.

WTIO24 FMEE 120616
SECURITE
GALE WARNING FOR METAREA VII
ISSUED BY METEO-FRANCE/TROPICAL CYCLONE CENTRE/LA REUNION 12/04/2007 AT
0600 UTC.
WARNING NUMBER: 003/15 (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).

GALE WARNING
BEGINNING OF VALIDITY: THURSDAY 12/04/2007 AT 0600 UTC.

PHENOMENON: EXTRATROPICAL DEPRESSION 15 1000 HPA
POSITION: 34.0S / 43.5E
(THIRTY FOUR DECIMAL ZERO DEGREES SOUTH AND FORTY THREE DECIMAL FIVE
DEGREES EAST) AT 0600 UTC
MOVEMENT: SOUTH-EAST 20 KT

THREAT AREAS:
SQUALLY WEATHER EXISTS LOCALLY WITHIN 150 NM RADIUS OF THE CENTER,
EXTENDING UP TO 500 NM IN THE SOUTHEASTERN SEMI-CIRCLE.

GALE FORCE WINDS 35/40 KT AND VERY ROUGH TO HIGH SEAS WITHIN 50 NM RADIUS
FROM THE CENTER.
NEAR GALE FORCE WINDS AND ROUGH TO VERY ROUGH SEAS WITHIN 80 NM FROM THE
CENTER, EXTENDING LOCALLY UP TO 300 NM IN THE SOUTHEASTERN SECTOR.
SRONG GUSTS UNDER SQUALLS.

FORECAST POSITION AND INTENSITY:
12H, VALID 2007/04/12 AT 18 UTC:
38.5S / 49.0E, MAX WIND = 40 KT, EXTRATROPICAL.
24H, VALID 2007/04/13 AT 06 UTC:
43.5S / 57.0E, MAX WIND = 40 KT, EXTRATROPICAL.

OTHER INFORMATIONS:
THIS SYSTEM TRACKS QUICKLY SOUTHEASTWARDS THANKS TO A TRANSIENT TROUGH IN
THE SOUTH, WITHIN A STRONGLY NORTHWESTERLY WINDSHEAR ENVIRONMENT.
THE LOW LEVEL CLOCKWISE CIRCULATION IS ASYMMETRICAL AND STRONG WINDS
EXTEND FAR IN THE SOUTH-EST DUE TO THE GRADIENT WITH THE SUBTROPICAL HIGH
PRESSURES. EXTENSION WINDS IS MEASURED THANKS TO RECENT SATELITE DATA.

[P.K.]

Well that answers the question on if they warn on subtropical systems or not then. Note this is listed as a tropical depression before turning subtropical. http://www.meteo.fr/temps/domtom/La_Reunion/TGPR/saison/15_table.html