Madagascar: OVERLAND DEPRESSION ex. IVAN (TC 18S)

[KWT]

Yeah thought that was the case, loads of dry air no wonder its getting well entrained into the circulation. If thats the case then the system will probably start to weaken again, maybe alot if that dry air continues to get into the circulation...

What direction is Ivan moving by the way?

[P.K.]

WTIO30 FMEE 111232

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

0.A WARNING NUMBER : 18/11/20072008
1.A TROPICAL CYCLONE 11 (IVAN)

2.A POSITION 2008/02/11 AT 1200 UTC :
14.3S / 65.0E
(FOURTEEN DECIMAL THREE DEGREES SOUTH AND SIXTY FIVE DECIMAL ZERO
DEGREES
EAST)

3.A DVORAK ANALYSIS : 4.5/4.5 /D
4.A CENTRAL PRESSURE : 970 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 65 KT

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 300 SE: 250 SO: 250 NO: 200
50 KT NE: 050 SE: 050 SO: 050 NO: 050

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1004 HPA / 1100
KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2008/02/12 00 UTC: 14.2S/65.4E, MAX WIND=070KT , TROPICAL
CYCLONE.
24H: 2008/02/12 12 UTC: 14.1S/65.1E, MAX WIND=075KT , TROPICAL
CYCLONE.
36H: 2008/02/13 00 UTC: 14.1S/64.6E, MAX WIND=080KT , TROPICAL
CYCLONE.
48H: 2008/02/13 12 UTC: 14.2S/63.8E, MAX WIND=085KT , TROPICAL
CYCLONE.
60H: 2008/02/14 00 UTC: 14.4S/62.2E, MAX WIND=090KT , INTENSE TROP.
CYCL.
.
72H: 2008/02/14 12 UTC: 14.7S/60.7E, MAX WIND=095KT , INTENSE TROP.
CYCL.
.

2.B OTHER INFORMATIONS:
T AND CI=4.5-

THE SYSTEM IS INTESIFYING PROGRESSIVELY, AN EYE IS NOW CONSOLIDATING
ON
SATELLITE IMAGERY.
IVAN IS EXPECTED TO GOING ON TRACK VERY SLOWLY GGLOBALLY
NORTHEASTWARDS
DURING THE NEXT 12 HOURS, THEN MORE WESTWARDS ALWAYS SLOWLY.

IVAN IS UNDERGOING TWO COMPETING STEERING FLOWS; SUBTROPICAL HIGH
PRESSURES REBUILDING IN THE SOUTH AND EQUATORIAL UPPER LEVEL RIGDE
THAT
REMAINS THE DOMMINANT STEERING FLOW FOR THE FIRST 12 HOURS.

IT SHOULD THEN INTENSIFY GRADUALLY WITHIN A FAVORABLE ENVIRONMENT.
GOOD
LOW LEVEL INFLOW (FOR THE BOTH SIDES) AND ALSO A FAVORABLE UPPER
LEVEL
SITUATION UNDER THE UPPER LEVEL RIDGE, WITH A GOOD EQUATORIAL
OUTFLOW.=

[Pedro Fernández]

I don't know why IVAN is still called officially 'severe tropical storm' when it is a category 1 (Saffir Simpson) cyclone tropical... In the last JTWC warning (06 UTC) is said it is showing an eye...

NRL is giving 959 mb and 85 KT... Almost a category 2 (SS) tropical cyclone

Meteo France, like all other worldwide agencies (except the Incompetent Met Deparment) use a 10-minute wind average in their warnings. Only the U.S. use a 1-minute sustained method, which makes winds appear stronger.

I understand... I will be careful with this difference. Thanks, Chacor

[HURAKAN]

That's why I have always called for a Joint Resolution to have a unified scale that can be used by all the meteorological agencies.

This would end problems like when there's a category 5 cyclone in the Australian scale being confused with a category 5 hurricane in the SS scale by the American media.

[Chacor]

This would end problems like when there's a category 5 cyclone in the Australian scale being confused with a category 5 hurricane in the SS scale by the American media.

For the most part though an Australian Category 5 is still usually a major hurricane equivalent in terms of 1-minute winds. And it's also prudent to remember that in its official bulletins (e.g. ICAO advisory, technical summary etc.) a 10-minute wind average is given first before the 3-sec wind gust.

If anything, it should be the American scale changed to a 10-minute scale, but that would create mass confusion.

[Squarethecircle]

The eyewall is still kind of open on microwave, but the storm overall looks okay on convective.

[Crostorm]

[HURAKAN]

[HURAKAN]

Doesn't look great.

[Pedro Fernández]

I recover last data from JTWC:

ZCZC 599
WTIO30 FMEE 111852
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 19/11/20072008
1.A TROPICAL CYCLONE 11 (IVAN)
2.A POSITION 2008/02/11 AT 1800 UTC :
14.2S / 64.9E
(FOURTEEN DECIMAL TWO DEGREES SOUTH AND SIXTY FOUR DECIMAL NINE
DEGREES
EAST)
3.A DVORAK ANALYSIS : 4.5/4.5 /D 0.5/12 H
4.A CENTRAL PRESSURE : 970 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 65 KT
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 300 SE: 250 SO: 250 NO: 200
50 KT NE: 050 SE: 050 SO: 050 NO: 050
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1004 HPA / 1100
KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS:
12H: 2008/02/12 06 UTC: 14.0S/64.8E, MAX WIND=070KT, TROPICAL
CYCLONE.
24H: 2008/02/12 18 UTC: 14.0S/64.5E, MAX WIND=075KT, TROPICAL
CYCLONE.
36H: 2008/02/13 06 UTC: 14.0S/63.8E, MAX WIND=080KT, TROPICAL
CYCLONE.
48H: 2008/02/13 18 UTC: 14.2S/62.6E, MAX WIND=085KT, TROPICAL
CYCLONE.
60H: 2008/02/14 06 UTC: 14.4S/61.1E, MAX WIND=090KT, INTENSE TROP.
CYCL..
72H: 2008/02/14 18 UTC: 15.2S/60.2E, MAX WIND=095KT, INTENSE TROP.
CYCL..
2.B OTHER INFORMATIONS:
T AND CI=4.5-
IVAN REMAINS UNEDR INFLUENCE OF TWO COMPETING STEERING FLOWS;
SUBTROPICAL
HIGH PRESSURES REBUILDING IN THE SOUTH AND EQUATORIAL UPPER LEVEL
RIGDE.
ENVIRONMENT REMAINS FAVOURABLE FOR INTENSIFICATION UNDER THE UPPER
LEVEL
RIDGE BUT AS THE SYSTEM IS QUASI-STATIONNARY SINCE SUNDAY EVENING ,
ITS
ENERGETIC POTENTIAL WEAKS DUE TO SEA WATER MIXED.
LAST MICROWAVE IMAGERY (1352Z SSMI AND 1600Z SSMIS) REVALS A LOW
LEVEL
CENTER (37V) SLIGHT DEPHASED SOUTHWARDS COMPARE TO THE UPPER LEVEL
OBVIOUS ONE (85H).
THIS VERTICAL WINDSHEAR IS NOT EXPECTED TO CONTINUE AND THE SYSTEM IS
EXPECTED TO RECURVE SLOWLY WESTWARDS.
BEYOND 24 HOURS, IVAN IS FORECASTED TO ACCELERATE ON THIS WESTWARDS
TRACK
IL COULD THEREFORE INTENSIFYING PROGRESSIVELY.=
NNNN

[HURAKAN]

Completely open.

[Crostorm]

[Crostorm]

ZCZC 642
WTIO30 FMEE 120046 CCA
*************** CORRECTIVE **************
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 20/11/20072008
1.A TROPICAL CYCLONE 11 (IVAN)
2.A POSITION 2008/02/12 AT 0000 UTC :
WITHIN 30 NM RADIUS OF POINT 14.1S / 64.6E
(FOURTEEN DECIMAL ONE DEGREES SOUTH AND SIXTY FOUR DECIMAL SIX
DEGREES
EAST)
3.A DVORAK ANALYSIS : 4.0/4.5 /W 0.5/12 H
4.A CENTRAL PRESSURE : 970 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 65 KT
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 300 SE: 250 SO: 250 NO: 200
50 KT NE: 050 SE: 050 SO: 050 NO: 050
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1004 HPA / 800 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS:
12H: 2008/02/12 12 UTC: 14.0S/64.0E, MAX WIND=070KT, TROPICAL
CYCLONE.
24H: 2008/02/13 00 UTC: 14.1S/63.2E, MAX WIND=070KT, TROPICAL
CYCLONE.
36H: 2008/02/13 12 UTC: 14.1S/61.9E, MAX WIND=080KT, TROPICAL
CYCLONE.
48H: 2008/02/14 00 UTC: 14.1S/60.9E, MAX WIND=085KT, TROPICAL
CYCLONE.
60H: 2008/02/14 12 UTC: 15.0S/59.3E, MAX WIND=090KT, INTENSE TROP.
CYCL..
72H: 2008/02/15 00 UTC: 15.7S/57.8E, MAX WIND=095KT, INTENSE TROP.
CYCL..
2.B OTHER INFORMATIONS:
T=4.0 AND CI=4.5-
IVAN REMAINS UNDER INFLUENCE OF TWO COMPETING STEERING FLOWS;
SUBTROPICAL
HIGH PRESSURES REBUILDING IN THE SOUTH AND EQUATORIAL UPPER LEVEL
RIGDE.
ENVIRONMENT REMAINS FAVOURABLE FOR INTENSIFICATION UNDER THE UPPER
LEVEL
RIDGE BUT AS THE SYSTEM IS QUASI-STATIONNARY SINCE SUNDAY EVENING ,
ITS
ENERGETIC POTENTIAL WEAKS DUE TO MIXED SEA WATER.
SINCE 6 HOURS, SYSTEM KEEPS ON TRACKING HOWEVER SLOWLY
WEST-NORTHWESTWARDS.
IT IS EXPECTED TO KEEPS ON TRACKING GLOBALLY WESTWARDS, SLOWLY WITHIN
THE
NEXT 24 HOURS AND ACCELERATING BEYOND. IT COULD THEREFORE
INTENSIFYING
PROGRESSIVELY.
BEYOND 48 HOURS, IVAN IS FORECASTED TO RECURVE PROGRESSIVELY
SOUTHWESTWARDS.
TRMM 2237Z MICROWAVE IMAGERY DON'T PERMIT TO CONFIRM SOUTHERLY
VERTICAL
WINDSHEAR REVEALED BY 1352Z SSMI AND 1600Z SSMIS MICROWAVE IMAGERY.=
NNNN

[wyq614]

Pressure increased for some 5hPa, it has downgraded to severe tropical storm.

But anyway Reunion is still optimistic towards the system.

[Crostorm]

ZCZC 403
WTIO30 FMEE 120622 RRA
RSMC / TROPICAL CYCLONE CENTRE / LA REUNION
TROPICAL CYCLONE FORECAST WARNING (SOUTH-WEST INDIAN OCEAN)
0.A WARNING NUMBER : 21/11/20072008
1.A SEVERE TROPICAL STORM 11 (IVAN)
2.A POSITION 2008/02/12 AT 0600 UTC :
14.1S / 64.6E
(FOURTEEN DECIMAL ONE DEGREES SOUTH AND SIXTY FOUR DECIMAL SIX
DEGREES
EAST)
3.A DVORAK ANALYSIS : 4.0/4.0 /W 0.5/12 H
4.A CENTRAL PRESSURE : 975 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 60 KT
6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 300 SE: 250 SO: 250 NO: 250
50 KT NE: 050 SE: 050 SO: 050 NO: 050
7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1005 HPA / 1000
KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP
1.B FORECASTS:
12H: 2008/02/12 18 UTC: 14.0S/63.7E, MAX WIND=060KT, SEVERE TROP.
STORM.
24H: 2008/02/13 06 UTC: 14.0S/62.6E, MAX WIND=070KT, TROPICAL
CYCLONE.
36H: 2008/02/13 18 UTC: 14.0S/61.3E, MAX WIND=075KT, TROPICAL
CYCLONE.
48H: 2008/02/14 06 UTC: 14.4S/59.9E, MAX WIND=080KT, TROPICAL
CYCLONE.
60H: 2008/02/14 18 UTC: 15.2S/58.4E, MAX WIND=085KT, TROPICAL
CYCLONE.
72H: 2008/02/15 06 UTC: 16.1S/56.9E, MAX WIND=090KT, INTENSE TROP.
CYCL..
2.B OTHER INFORMATIONS:
T=4.0- AND CI=4.5+
NNNN

[Chacor]

WTIO30 FMEE 121217

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

0.A WARNING NUMBER : 22/11/20072008
1.A SEVERE TROPICAL STORM 11 (IVAN)

2.A POSITION 2008/02/12 AT 1200 UTC :
WITHIN 20 NM RADIUS OF POINT 14.0S / 64.2E
(FOURTEEN DECIMAL ZERO DEGREES SOUTH AND SIXTY FOUR DECIMAL TWO DEGREES
EAST)

3.A DVORAK ANALYSIS : 3.0/3.5 /W 1.0/24 H
4.A CENTRAL PRESSURE : 985 HPA
5.A MAX AVERAGE WIND SPEED (10 MN) : 50 KT

6.A EXTENSION OF WINDS BY QUADRANTS (KM):
30 KT NE: 150 SE: 200 SO: 250 NO: 250
50 KT NE: 030 SE: 030 SO: 030 NO: 030

7.A FIRST CLOSED ISOBARE (PRESSURE / AVERAGE DIAM): 1005 HPA / 1000 KM
8.A VERTICAL EXTENSION OF CYCLONE CIRCULATION: DEEP

1.B FORECASTS:
12H: 2008/02/13 00 UTC: 14.1S/63.2E, MAX WIND=050KT, SEVERE TROP. STORM.
24H: 2008/02/13 12 UTC: 14.1S/61.9E, MAX WIND=040KT, MODERATE TROP. STORM
.
36H: 2008/02/14 00 UTC: 14.3S/60.5E, MAX WIND=040KT, MODERATE TROP. STORM
.
48H: 2008/02/14 12 UTC: 14.9S/59.2E, MAX WIND=060KT, SEVERE TROP. STORM.
60H: 2008/02/15 00 UTC: 15.8S/57.6E, MAX WIND=070KT, TROPICAL CYCLONE.
72H: 2008/02/15 12 UTC: 16.7S/56.0E, MAX WIND=080KT, TROPICAL CYCLONE.

2.B OTHER INFORMATIONS:
T=3.0 AND CI=3.5
DEEP CONVECTION ASSOCIATED TO THE SYSTEM BARELY CONSOLIDATES IN THE
SOUTHERN PART AS SHOWED ON THE MICROWAVE IMAGERY (TRMM 11/2237Z, F14
12/0018Z, F16 12/0311Z) ; BEING QUASISTATIONARY OVER THE LAST 36 HOURS,
THE OCEANIC HEAT POTENTIAL HAS WEAKENED.
IVAN REMAINS UNDER THE INFLUENCE OF TWO COMPETING STEERING FLOWS;
SUBTROPICAL HIGH PRESSURES REBUILDING IN THE SOUTH AND EQUATORIAL UPPER
LEVEL RIGDE.
THE SYSTEM SEEMS HOWEVER TO TRACK SLOWLY WESTWARDS OVER THE LAST HOURS.
IT SHOULD THEN SPEED UP BEYOND 24 HOURS ALONG THE NORTHERN EDGE OF THE
SUBTROPICAL RIDGE BECOMING THE PRIMARY STEERING FLOW, AND THEN REGULARLY
INTENSIFY BEYOND 36 HOURS WITHIN A FAVORABLE ENVIRONEMENT, UNDER THE
UPPER LEVEL RID
GE AND FAR FROM THE AREA OF LOWER OCEAN HEAT CONTENT.
BEYOND 48 HOURS, IVAN IS FORECASTED TO RECURVE GRADUALLY SOUTHWESTWARDS
AS THIS SUBTROPICAL RIDGE WEAKENS.

[HURAKAN]

Looking really bad.

[Squarethecircle]

Hehe... I'm not entirely sure that this is a 65 knot storm.

[Crostorm]

Looks very bad

[Squarethecircle]

Completely utterly destroyed. I would not call it a significant tropical cyclone.