TD Mahasen - Northeastern India // TC Alvin - Manzanillo, Mexico

Seychelles Meteorological Services
Tropical Cyclone Advisory #6
ZONE PERTURBEE, FORMER IRINA (11-20112012)
16:00 PM RET February 28 2012
=====================================

At 12:00 PM UTC, Area Of Disturbed Weather, Former Irina (997 hPa) located at 16.3S 44.0E has 10 minute sustained winds of 20 knots with gusts of 35 knots. The cyclone is reported as moving west southwest at 5 knots.

Dvorak Intensity: 1.5/1.5/S0.0/0 HRS

Forecast and Intensity
========================

12 HRS: 16.3S 43.5E - 25 knots (Perturbation Tropicale)
24 HRS: 16.4S 43.1E - 35 knots (Tempête Tropicale Modérée)
48 HRS: 17.9S 42.2E - 55 knots (Forte Tempête Tropicale)
72 HRS: 21.3S 40.3E - 60 knots (Forte Tempête Tropicale)

Additional Information
=======================

Low level circulation has come back over seas yesterday, then has tracked along the northwestern coast of madagascar. Low level circulation center remains very difficult to localize. Current position is estimated thanks to 0900z and 1200 PM UTC Malagasy observations (Belasampy and Majunga) and Juan de Nova.The clockwise circulation is expected to go far from the coast in the next hours, coming back over a complete overseas environment.

Most of available numerical weather prediction models are in good agreement. System is expected to track globally west on the northern edge of subtropical ridge existing in the south for the next 24 hours, then southwestwards. The moderate easterly wind shear, is always limiting system intensification, but it is forecast to weaken.

Easterly wind shear should limit potential for regeneration but this shear is expected to weaken. On wednesday and thursday, the very good equatorward upper level outflow is expected to combine to a strong poleward one, environmental conditions should progressively improve and become favorable for significative further re-intensification. An oversea track in the middle of the channel within this favourable environment should allow ex-Irina to reach tropical cyclone stage on wednesday. Beyond an easterly upper level constraint should weaken it on Saturday.

Numerical weather prediction available forecast tracks invite the inhabitants of the Mozambique coastline to the greatest caution. It's currently not possible to precisely target the potential threatened areas. The all long Mozambique coastline from 18.0s to 27.0s should be influences directly or indirectly by this system.

Current intensity does not justify issuance of regular warning. It remains however closely monitored in relationship with its potential for intensification.

For further information about this system when no tropical cyclone forecast advisory (WTIO30) is issued, refer to bulletin AWIO20 for cyclonic activity and significant tropical weather in the southwest Indian ocean issued by the RSMC daily at 1200 PM UTC.

RSMC Reunion
Tropical Cyclone Outlook
15:00 PM RET February 28 2012
==========================

Area of Disturbed Weather (IRINA)
======================

refer to current tropical cyclone advisory issued at 12:00 PM UTC..

More eastern of disturbance NR 11
========================

a low estimated at 1001 hPa, is approximately centered near 11.8S 69.5E, with winds about 15-20 knots.
In addition to a moderate southeasterly wind shear, the both zonal westerly and easterly flows not efficient are an hindrance for rapid cyclogenesis.

On and after Wednesday, monsoon inflow becomes more direct, poleward low level inflow also improves (phased with a rebuilding high pressures in the south) and vertical wind shear is expected
to weaken, the low should then deepen significantly. Numerical weather prediction models strongly divergent until yesterday, seem to be quite agree with a globally southwards track.

For the next 24 hours, the potential for development of a tropical depression is fair to good with the zone of disturbed weather nr11 (Irina).

Seychelles Meteorological Services
Tropical Cyclone Advisory #7
DEPRESSION TROPICALE, FORMER IRINA (11-20112012)
4:00 AM RET February 29 2012
=====================================

At 0:00 AM UTC, Tropical Depression, Former Irina (994 hPa) located at 16.3S 43.4E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The cyclone is reported as moving west at 4 knots.

Near Gale Force Winds
=============
30 NM radius from the center extending up to 45 NM in the northwestern quadrant

Dvorak Intensity: T2.5/2.5/S0.0/0 HRS

Forecast and Intensity
========================

12 HRS: 16.7S 42.9E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 17.3S 42.6E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 20.3S 41.2E - 60 knots (Forte Tempête Tropicale)
72 HRS: 22.4S 38.0E - 80 knots (Cyclone Tropical)

Additional Information
=======================

Low level circulation center remains very difficult to precisely localize. Deep convective activity enforces and organizes in a curved band pattern in the west of the estimated center. Most of available numerical weather prediction models are in good agreement. System is expected to track globally southwest on the northwestern edge of the subtropical ridge. Vertical wind shear keeps on weakening aloft as previously forecast allowing the system to intensify. On Wednesday and Thursday, the very good equatorward upper level outflow is expected to combine to a strong poleward one, environmental conditions should progressively improve and become favorable for significant further re-intensification. An oversea track in the middle of the channel within this favorable environment should allow the system to reach tropical cyclone stage on Friday.

Available numerical weather prediction forecast tracks are in good agreement to a landfall on the Mozambique coastline. The potential threatened areas remains difficult at this range to be precisely targeted but runs after runs concentrates in a region between Beira and Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..

Mauritius Meteorological Services
Tropical Cyclone Advisory #1
PERTURBATION TROPICALE 12-20112012
4:00 AM RET February 29 2012
==============================

At 0:00 AM UTC, Tropical Disturbance 12 (999 hPa) located at 12.5S 69.2E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving south at 3 knots.

Dvorak Intensity: T2.0/2.0/D0.5/12 HRS

Forecast and Intensity
==============

12 HRS: 13.3S 69.1E - 30 knots (Depression Tropicale)
24 HRS: 14.5S 68.2E - 30 knots (Depression Tropicale)
48 HRS: 16.6S 67.7E - 30 knots (Depression Tropicale)
72 HRS: 19.0S 68.8E - 35 knots (Tempête Tropicale Modérée)

Additional Information
================

Since 1800 PM UTC, deep convective activity has consolidated near the center and organized on a curved band pattern. SSMI F15 2310 PM UTC confirms this better feature. Low level inflow improves on the both sides and easterly vertical wind shear has temporarily weakened but is forecast to enforce back today late and tomorrow Thursday. Numerical weather prediction models are now in good agreement to forecast a globally southwards motion. Over this expected track, environmental conditions should become favorable on Friday under the upper level ridge but a new northerly vertical wind shear constraint should established on and after Saturday. Potential for intensification is therefore limited at short or medium range.

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 6:30 AM UTC..

Mauritius Meteorological Services
Tropical Cyclone Advisory #2
DEPRESSION TROPICALE 12-20112012
10:00 AM RET February 29 2012
==============================

At 6:00 AM UTC, Tropical Depression 12 (997 hPa) located at 12.6S 68.4E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west southwest at 6 knots.

Near Gale Force Winds
==============
40 NM radius from the center extending up to 60 NM in the southern semi-circle

Dvorak Intensity: T2.5/2.5/D1.0/24 HRS

Forecast and Intensity
==============

12 HRS: 13.3S 67.5E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 14.3S 66.1E - 35 knots (Tempête Tropicale Modérée)
48 HRS: 16.7S 64.0E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 18.7S 64.5E - 45 knots (Tempête Tropicale Modérée)

Additional Information
================

The cloud pattern is now a cold clouds top central dense overcast. Latest burst of convection has started at 0300 AM UTC. Microwave imagery reveal a rather small core system and it is possible that the system may have already reached the moderate tropical storm level.

Low level inflow improves on the both sides. The upper level trough located yesterday closed to the southwest of the system is now moving away allowing an improvement of the upper level divergence as seen with the impressive outflow pattern (more limited in the eastern sector however).

The system should be to the north of the upper level ridge until Thursday night and experiencing some easterly shear. So intensification should be rather limited until that time. Friday, environmental conditions should become favorable under the upper level ridge but a new northerly vertical wind shear constraint should established on and after Saturday. Overall, the potential of intensification appears rather low ... However given the small size of the inner core, some stronger variations in intensity than presently indicated could be observed.

The track forecast is significantly adjusted to the west based on first 0000 AM UTC guidance output. The system should round the subtropical highs located to its east and should be Friday night ahead of a new upper to mid level trough. The track could take by that time a southeastwards motion. At the end of the forecast, a weakening system should track westwards within a low level steering flow.

Inhabitants of Rodriguez island should start to monitor the progress of this system.

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 12:30 PM UTC..

Seychelles Meteorological Services
Tropical Cyclone Advisory #8
DEPRESSION TROPICALE, FORMER IRINA (11-20112012)
10:00 AM RET February 29 2012
=====================================

At 6:00 AM UTC, Tropical Depression, Former Irina (993 hPa) located at 16.6S 43.9E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The cyclone is reported as moving south southwest at 2 knots.

Near Gale Force Winds
=============
30 NM radius from the center extending up to 45 NM in the northwestern quadrant

Dvorak Intensity: T 2.5/2.5/S0.0/6 HRS

Forecast and Intensity
========================

12 HRS: 17.5S 43.6E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 18.6S 43.2E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 22.3S 40.7E - 60 knots (Forte Tempête Tropicale)
72 HRS: 23.9S 36.9E - 80 knots (Cyclone Tropical)

Additional Information
=======================

It is still difficult to locate accurately the low level circulation center, but it is probably very close from the coast (cf. Mean sea level pressure 993hpa at Besalampy at 0300 AM UTC). According to the last microwave imagery (F17 at 0301 AM UTC) cloud pattern remains poorly organized. Last animated METEOSAT pictures depict fluctuating deep convection close to the estimated center.

Most of available numerical weather prediction models are in good agreement. System is expected to track globally southwestward on the northwestern edge of the subtropical ridge. Vertical wind shear keeps on weakening aloft. Upper divergence is rather favorable and is expected to improve poleward through 72 hours.

Within this favorable environment, and as the low level circulation center is removing progressively from the Malagasy coast, system is forecast to intensify and should reach tropical cyclone stage on Friday. Available numerical weather prediction forecast tracks are in good agreement for a landfall on the Mozambique coastline. The potential threatened areas remains difficult at this range to be precisely targeted but runs after runs concentrates in a region between Beira and Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..

Mauritius Meteorological Services
Tropical Cyclone Advisory #3
DEPRESSION TROPICALE 12-20112012
16:00 PM RET February 29 2012
==============================

At 12:00 PM UTC, Tropical Depression 12 (997 hPa) located at 13.5S 67.8E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving southwest at 9 knots.

Near Gale Force Winds
==============
40 NM radius from the center extending up to 120 NM in the southeastern quadrant and up to 150 NM in the southwestern quadrant

Dvorak Intensity: T2.5/2.5/D1.0/24 HRS

Forecast and Intensity
==============

12 HRS: 14.2S 66.9E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 15.2S 65.9E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 17.7S 65.4E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 20.9S 66.7E - 35 knots (Tempête Tropicale Modérée)

Additional Information
================

The cloud pattern has not significantly improved during the last 6 hours. It is still an irregular central dense overcast less than 90 NM in diameter on visible 0924 AM UTC N19 imagery. Some significant fluctuation in size and shape of this central dense overcast appear associated to the occurrence of convective burst. The system remains a small size inner-core system.

Low level inflow improves on the both sides. The upper level divergence remains impressive and seems to improve over the eastern side according to latest satellite pics.

The system tracks now southwestwards and is getting closer of the upper level ridge. Although some easterly shear could remain tomorrow, it appears likely that the system will gain a little bit of strength. Friday, environmental conditions should be at its best under the upper level ridge ... Present intensity forecast is rather low given that few or none of the guidance strengthen significantly the system until Friday ... However given the small size of the inner core, one could note that some stronger variations in intensity than presently indicated could be observed.

From Saturday to the end of the forecast period, a new northerly vertical wind shear constraint should established. However most of the guidance deepen the system by that time. Further analysis show that this intensification may come from baroclinic process ... Consequently, en extratropical transition may begin Sunday.

The system should round the subtropical highs located to its east and should be Friday night ahead of a new upper to mid level trough. The track could take by that time a south eastwards motion between the trough located to its southwest and the subtropical ridge to its northeast . After that, the predicted scenario is westwards turn on the northern side of the subtropical ridge. ECMWF ensemble forecast show some significant spread around this "s" track.

If the present track forecast a lower threat for Rodriguez, inhabitants of Rodrigues island should monitor the progress of this system, as a more serious threat could not be ruled out during the next few days ...

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 18:30 PM UTC..

Seychelles Meteorological Services
Tropical Cyclone Advisory #9
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET February 29 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (991 hPa) located at 16.0S 43.4E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 2 knots.

Gale Force Winds
==========
in northern semi-circle

Near Gale Force Winds
=============
50 NM radius from the center extending up to 80 NM in the northern semi-circle

Dvorak Intensity: T2.5/2.5/D1.0/24 HRS

Forecast and Intensity
========================

12 HRS: 16.8S 43.2E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 18.4S 42.9E - 50 knots (Forte Tempête Tropicale)
48 HRS: 22.7S 40.1E - 65 knots (Cyclone Tropical)
72 HRS: 23.7S 36.3E - 85 knots (Cyclone Tropical)

Additional Information
=======================

The low level circulation center has moved generally westward over the past 6 hours. 0600z AM UTC fix is relocated near 16.2S 43.8E.

Convection wraps of 0,5 around the low level circulation center Upper level divergence is improving westward (cf. water vapor channel).

System is undergoing two competing zonal steering flows in the mid-troposphere, with the near-equatorial ridge and the subtropical ridge. Tomorrow (Thursday) , system should accelerate south-south-westward towards a barometric col. On Friday, the track should curve west southwestward with the rebuilding of the subtropical high pressure.

System is actually almost under the axis of the upper tropospheric ridge, axed near 17s. Upper vertical wind shear is weak. A good outflow channel exists equatorward. It is forecast to be replaced by tomorrow by a good outflow channel poleward.

Environmental conditions remain also favorable for intensification of the system that should reach the stage of mature tropical cyclone for the forecast landfall on Saturday afternoon or Sunday morning north of Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..

Mauritius Meteorological Services
Tropical Cyclone Advisory #4
DEPRESSION TROPICALE 12-20112012
22:00 PM RET February 29 2012
==============================

At 18:00 PM UTC, Tropical Depression 12 (996 hPa) located at 13.9S 67.6E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving south at 7 knots.

Near Gale Force Winds
==============
40 NM radius from the center extending up to 120 NM in the southeastern quadrant and up to 150 NM in the southwestern quadrant

Dvorak Intensity: T2.5/2.5/D0.5/24 HRS

Forecast and Intensity
==============

12 HRS: 14.8S 66.5E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 15.7S 65.2E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 17.6S 64.3E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 20.4S 66.5E - 35 knots (Tempête Tropicale Modérée)

Additional Information
================

The cloud pattern is still an irregular central dense overcast. Some significant fluctuations in size and shape of this central dense overcast appear associated to the occurrence of convective burst, and seems undergoing a little easterly upper level constraint . The system remains a small size inner-core system.

Low level inflow improves on the both sides. The upper level divergence remains impressive but always quite limited over the eastern side.

The system tracks now south southwestwards and is getting closer of the upper level ridge. Although some easterly shear could remain tomorrow, it appears likely that the system will gain a little bit of strength. Friday, environmental conditions should be at its best under the upper level ridge ... Present intensity forecast is rather low given that few or none of the guidance strengthen significantly the system until Friday ... However given the small size of the inner core, one could note that some stronger variations in intensity than presently indicated could be observed.

From Saturday to the end of the forecast period, a new northerly vertical wind shear constraint should established. However most of the guidance deepen the system by that time. Further analysis show that this intensification may come from baroclinic process ... Consequently, en extratropical transition may begin Sunday.

The system should round the subtropical highs located to its east and should be Friday night ahead of a new upper to mid level trough. The track could take by that time a southeastwards motion between the trough located to its southwest and the subtropical ridge to its northeast . After that, the predicted scenario is westwards turn on the northern side of the subtropical ridge. ECMWF ensemble forecast show some significant spread around this "s" track.

Inhabitants of Rodriguez Island should monitor the progress of this system, as a more serious threat could not be ruled out during the next few days ...

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 0:30 AM UTC..

Seychelles Meteorological Services
Tropical Cyclone Advisory #10
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET February 29 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (985 hPa) located at 16.6S 43.5E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving west at 2 knots.

Gale Force Winds
==========
35 NM radius from the center

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 100 NM in the northern semi-circle

Dvorak Intensity: T3.5/3.5/D1.5/24 HRS

Forecast and Intensity
========================

12 HRS: 17.6S 43.1E - 55 knots (Forte Tempête Tropicale)
24 HRS: 19.2S 42.7E - 60 knots (Forte Tempête Tropicale)
48 HRS: 22.6S 40.1E - 70 knots (Cyclone Tropical)
72 HRS: 23.5S 36.4E - 85 knots (Cyclone Tropical)

Additional Information
=======================

Low level circulation center has tracked slowly westwards during the next 6 hours. Deep convective activity enforces and organizes in a curved band pattern, as the system is deepening.

The very good equatorward upper level outflow has combined today's to a strong poleward one, allowed a rapid intensification of the system during the next hours. On and beyond tomorrow Thursday, only the polar one is forecast to remain.

System is undergoing two opposite steering influences, in medium troposphere. The first one associated with an equatorial ridge located northward and the other one associated with the subtropical ridge located southward. Tomorrow Thursday, the system should accelerate south south-eastwards towards a col. On Friday as the subtropical highs rebuild the track should recurved west southwestwards.

This favorable environment should allow the system to reach tropical cyclone stage on Friday. Available numerical weather prediction forecast tracks are in good agreement to a landfall on the Mozambique coastline Saturday afternoon or on Sunday morning.The potential threatened areas remains difficult at this range to be precisely targeted but runs after runs concentrates in a region between Beira and Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..