Tropical Depression

By: HadesGodWyvern , 2:40 AM GMT on March 01, 2012

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Northwest Pacific Ocean
=========================

Area of Responsibility
==============================
RSMC: Japan Meteorological Agency

Storm archives (Active Storms in Color)
======================================

March
T201201.Pakhar - 998 hPa

April
Tropical Depression "90C" - 1004 hPa
Tropical Depression - 1008 hPa


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North Indian Ocean
=========================

Area of Responsibility
==============================
RSMC: India Meteorological Department


Storm archives (Active Storms in Color)
======================================


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=======================
Southeastern Pacific Ocean
=======================

Area of Responsibility
==============================
RSMC: Nadi Meteorological Services

Storm archives (Active Storms in Color)
======================================

March
14F.NONAME - 1005 hPa
15F.NONAME - 1005 hPa
16F.NONAME - 1003 hPa
17F.NONAME - 999 hPa
18F.NONAME - 1004 hPa
19F.Daphne - 985 hPa

April
20F.NONAME - 1009 hPa

------------------------------------------------- --

==========================
Southwestern Pacific Ocean
==========================

Area of Responsibility
==============================
RSMC: Bureau of Meteorology

Storm archives (Active Storms in Color)
======================================

March
17U.NONAME - 991 hPa


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==========================
Southeastern Indian Ocean
==========================

Area of Responsibility
==============================
RSMC: Bureau of Meteorology

Perth Tropical Cyclone Warning Center
---------------------------------------------

Storm archives (Active Storms in Color)
======================================

March
15U.Koji - 993 hPa (moved west of 90E)
16U.LUA - 932 hPa

------------------------------------------------- -----

==========================
Southwestern Indian Ocean
==========================

Area of Responsibility
==============================
RSMC: Mauritius Meteorological Services
Seychelles Meteorological Services

Storm archives (Active Storms in Color)
======================================

March
11R.Irina - 979 hPa
12R.NONAME - 996 hPa
13R.Joni - 980 hPa (Entered from TCWC Perth - TC Koji)


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Perth Tropical Cyclone Warning Center
Tropical Cyclone Outlook
FORECAST WESTERN AUSTRALIA REGION BETWEEN 90E-125E SOUTH OF 10S
12:47 PM WST March 9 2012
=========================

A low is developing south southwest of Bali in the vicinity of 13S 112E. It is possible that it will develop into a tropical cyclone as early as Sunday but it is more likely to reach tropical cyclone intensity during next week. This low is expected to move generally southwards and may be located off the Pilbara coast for much of next week. The risk of a coastal impact increases during the week. Pilbara and Kimberley coastal communities are advised to keep up to date with weather forecasts over the coming days.

Tropical Cyclone Formation Potential
=======================

Saturday: Low
Sunday: Moderate
Monday: High
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #4
FORTE TEMPETE TROPICALE JONI (13-20112012)
10:00 AM RET March 9 2012
=====================================

At 6:00 AM UTC, Severe Tropical Storm Joni (980 hPa) located at 17.1S 86.3E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving west southwest at 10 knots.

Storm Force Winds
============
25 NM radius from the center

Gale Force Winds
==========
50 NM radius from the center, extending up to 70 NM in the northwestern quadrant, up to 100 NM in the southwestern quadrant, and up to 150 NM in the southeastern quadrant

Near Gale Force Winds
=============
70 NM radius from the center , extending up to 100 NM in the northwestern quadrant, up to 260 NM in the southeastern quadrant, and up to 270 NM in the southwestern quadrant

Dvorak Intensity: T4.0/4.0/D1.0/24 HRS

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

12 HRS: 18.0S 83.5E - 55 knots (Forte Tempête Tropicale)
24 HRS: 19.2S 81.1E - 55 knots (Forte Tempête Tropicale)
48 HRS: 21.6S 78.8E - 60 knots (Forte Tempête Tropicale)
72 HRS: 25.6S 78.8E - 50 knots (Forte Tempête Tropicale)

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

SSMIS pass of 0203 AM UTC show always an eye pattern in the mid level but not vertically in phase with the low level center (displaced to the northeast of the mid level eye)

The track forecast philosophy has not changed much within the next three days: Koji-Joni is expected to keep on tracking globally west southwestwards on the northern edge of the subtropical mid-level ridge. This feature is expected to gradually weaken tomorrow with a weakness located along 80.0E. On this track, easterly wind shear is expected to keep on existing aloft but is expected to gradually relax Saturday and allow some little strengthening.

Saturday and Sunday, the system is expected to recurve southwards in the weakness and towards a transiting mid-latitude trough. Late Saturday, environmental conditions should be at their best for the system as it should lie along the upper level ridge ... However some northerly shear is likely to maintain a bit by that time. Sea surface temperature and oceanic heat contain are favorable up to around 22.0S.

Sunday and beyond, the system will move over cooler waters and undergo an increase in northerly shear ..so a weakening trend is expected bu that time. By the end of the forecast period, latest ECMWF output show now a continuing southwards track without a clear westwards turn. Given the rather high spread amongst the guidance by that time, the current forecast is close to the mean solution.

The next tropical cyclone advisory on TC Joni from Mauritius Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #3
FORTE TEMPETE TROPICALE JONI (13-20112012)
4:00 AM RET March 9 2012
=====================================

At 0:00 AM UTC, Severe Tropical Storm Joni (980 hPa) located at 17.0S 87.3E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving west southwest at 10 knots.

Storm Force Winds
============
25 NM radius from the center

Gale Force Winds
==========
50 NM radius from the center, extending up to 70 NM in the northwestern quadrant, up to 100 NM in the southwestern quadrant, and up to 150 NM in the southeastern quadrant

Near Gale Force Winds
=============
70 NM radius from the center , extending up to 100 NM in the northwestern quadrant, up to 260 NM in the southeastern quadrant, and up to 270 NM in the southwestern quadrant

Dvorak Intensity: T4.0/4.0/D0.5/6 HRS

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

12 HRS: 17.6S 84.7E - 55 knots (Forte Tempête Tropicale)
24 HRS: 18.2S 82.6E - 60 knots (Forte Tempête Tropicale)
48 HRS: 20.1S 79.6E - 55 knots (Forte Tempête Tropicale)
72 HRS: 23.2S 78.5E - 40 knots (Tempête Tropicale Modérée)

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

T=4.0- and CI=4.0-

Satellite presentation has improved overnight. TRMM pass of 2054 PM UTC show an eye pattern in the mid level but not vertically in phase with the low level center (displaced to the northeast of the mid level eye)

The track forecast philosophy has not changed much within the next three days: Koji-Joni is expected to keep on tracking globally west-south-westwards on the northern edge of the subtropical mid-level ridge. This feature is expected to gradually weaken tomorrow with a weakness located along 80.0E. On this track, easterly wind shear is expected to keep on existing aloft but is expected to gradually relax and allow some strengthening.

Saturday and Sunday, the system is expected to recurve southwards in the weakness and towards a transiting mid-latitude trough. Late Saturday, environmental conditions should be at their best for the system as it should lie along the upper level ridge ... However some northerly shear is likely to maintain a bit by that time. sea surface temperature and oceanic heat contain are favorable up to around 22s.

Sunday and beyond, the system will move over cooler waters and undergo an increase in northerly shear ... So a weakening trend is expected bu that time. By the end of the forecast period, latest ECMWF output show now a continuing southwards track without a clear westwards turn. Given the rather high spread amongst the guidance by that time, the current forecast is close to the mean solution.

The next tropical cyclone advisory on TC Joni from Mauritius Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #43
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 9 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (996 hPa) located at 29.3S 38.8E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The cyclone is reported as moving west at 7 knots.

Gale Force Winds
==========
20 NM in the northeastern quadrant, up to 65 NM in the southeastern quadrant, and up to 75 NM in the southwestern quadrant

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 55 NM in the northwestern quadrant, up to 85 NM in the southeastern quadrant, and up to 105 NM in the southwestern quadrant

Dvorak Intensity:

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

12 HRS: 29.2S 37.9E - 30 knots (Depression Tropicale)
24 HRS: 28.9S 37.0E - 30 knots (Depression Tropicale)
48 HRS: 26.3S 35.8E - 25 knots (Perturbation Tropicale)
72 HRS: 22.1S 34.5E - Depression sur Terre

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

Latest ASCAT data confirms current intensity at 1800 PM UTC. Since that time, the cloud pattern has continued to deteriorate on satellite imagery.

The system still drifts slowly westwards ... Or west northwestwards according to latest fix. It is expected to keep on shifting slowly globally west northwestwards until Saturday morning on the northern edge of a weak mid level ridge. Beyond, high pressures located over South Africa will steer the system north northwestwards.

Throughout the forecast period, sea surface temperature remain marginal (25 to 26C). The wind shear is still rather low but is expected to strengthen this afternoon and maintain the current weakening trend.

Irina should be a filling up low by the time it will make landfall near Inhambane. Consequently Irina should not be considered anymore as a threat for Mozambique.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #42
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 8 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (991 hPa) located at 29.7S 39.8E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west southwest at 3 knots.

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

Near Gale Force Winds
=============
90 NM radius from the center

Dvorak Intensity:

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

12 HRS: 29.6S 38.8E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 29.4S 37.7E - 35 knots (Tempête Tropicale Modérée)
48 HRS: 28.3S 36.3E - 30 knots (Depression Tropicale)
72 HRS: 24.3S 35.1E - Depression sur Terre

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

Irina briefly shows a simile eye feature on infrared imagery this evening. Microwave imagery shows a beterioration of the convective pattern. System still drift slowly westward and is expected to keep on shifting slowly globally west northwestward until Saturday morning. On the northern edge of a weak mid level ridge (slower timing in regard of previous forecast).

Beyond, high pressures located over South Africa will steer the system north northwestwards. Throughout the forecast period, sea surface temperature remain marginal 25-26C) wind shear should be rather low, as the system would lie under an upper level anticyclone, until Friday afternoon. However, very slow motion on weak oceanic heat content do not allow any increase in intensity. Northerly then northwesterly vertical wind shear is expected to increase again Friday night and the system is therefore expected to weaken slightly before its landfall that is forecast on Sunday over the Inhambane area. Irina should be a filling up low by that time and likely not be considered as a threat anymore for Mozambique.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #2
FORTE TEMPETE TROPICALE JONI (13-20112012)
22:00 PM RET March 8 2012
=====================================

At 18:00 PM UTC, Severe Tropical Storm Joni (984 hPa) located at 16.5S 88.2E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving west at 12 knots.

Storm Force Winds
============
25 NM radius from the center

Gale Force Winds
==========
50 NM radius from the center, extending up to 60 NM in the northwestern quadrant, up to 105 NM in the southwestern quadrant, and up to 140 NM in the southeastern quadrant

Near Gale Force Winds
=============
70 NM radius from the center, extending up to 80 NM in the northwestern quadrant, up to 260 NM in the southeastern quadrant, and up to 270 NM in the southwestern quadrant

Dvorak Intensity: T3.5/3.5/S0.0/6 HRS

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

12 HRS: 16.8S 86.1E - 50 knots (Forte Tempête Tropicale)
24 HRS: 17.4S 84.0E - 55 knots (Forte Tempête Tropicale)
48 HRS: 19.5S 80.8E - 60 knots (Forte Tempête Tropicale)
72 HRS: 22.2S 79.5E - 50 knots (Forte Tempête Tropicale)

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

Tropical Cyclone Koji has been renamed after crossing 90E (thus leaving the area of responsibility of TCWC Perth)

T=3.5 AND CI=3.5

Koji-Joni shows a very cold convective cloud mass (cloud top below -90C on MET7 infrared imagery). Some easterly shear s still present with restricted outflow on the eastern border of the convective mass. It is expected to keep on tracking globally west southwestward on the northern edge of the subtropical mid-level ridge. This feature is expected to gradually weaken tomorrow with a weakness located along 80E.

Over this forecast track, easterly wind shear is expected to keep on existing aloft and intensity variations are expected from Saturday, system is expected to recurve southward in the weakness and towards a transiting mid-latitude trough and after a temporarily sheared relax, is expected within Sunday to undergo a new north northwesterly vertical wind shear constraint. System should therefore clearly weaken and its remnants should then been steered westward by trade winds flow.

The next tropical cyclone advisory on TC Joni from Mauritius Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #1
FORTE TEMPETE TROPICALE KOJI-JONI (13-20112012)
16:00 PM RET March 8 2012
=====================================

At 12:00 PM UTC, Severe Tropical Storm Joni (984 hPa) located at 16.6S 89.6E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving west southwest at 13 knots.

Storm Force Winds
============
20-25 NM radius from the center

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

Near Gale Force Winds
=============
80 NM radius from the center extending up to 100 NM in the southern semi-circle

Dvorak Intensity: T3.5/3.5/D1.0/24 HRS

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

12 HRS: 17.4S 87.3E - 50 knots (Forte Tempête Tropicale)
24 HRS: 18.0S 84.9E - 50 knots (Forte Tempête Tropicale)
48 HRS: 20.2S 81.1E - 50 knots (Forte Tempête Tropicale)
72 HRS: 22.9S 79.9E - 40 knots (Tempête Tropicale Modérée)

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

Tropical storm Koji has been renamed Koji-Joni after crossing longitude 90°E (thus leaving the area of responsibility of TCWC Perth to enter the area of responsibility of RSMC Reunion). This is a consequence of a new procedure adopted in 2010 for the southwest Indian Ocean basin. While the principle of moving towards not renaming named storms coming from the southeast Indian Ocean has been agreed upon, as an interim phase it has been decided to append a hyphenated name from the southwest Indian Ocean naming list to the existing name of the system moving from the southeast Indian Ocean.

System has progressively organize within the last 24 hours hours. It is expected to keep on tracking globally west southwestwards on the northern edge of the subtropical high pressures belt. Over this forecast track, easterly wind shear is expected to keep on existing aloft and intensity variations are expected. From Saturday, system is expected to recurve southwards towards a transiting mid-latitude trough and after a temporarily sheared relax, is expected within Sunday to undergo a new north northwesterly vertical wind shear constraint. System should therefore clearly weaken and its remnants should then been steered westwards by trade winds flow.

The next tropical cyclone advisory on TC Joni from Mauritius Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #41
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 8 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (991 hPa) located at 29.5S 40.0E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west southwest at 3 knots.

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

Near Gale Force Winds
=============
90 NM radius from the center

Dvorak Intensity:

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

12 HRS: 29.7S 39.1E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 29.7S 38.0E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 29.2S 36.8E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 25.8S 35.6E - 25 knots (Perturbation Tropicale)

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

System drifts slowly westwards and is expected to keep on shifting slowly globally west northwestwards then westwards until Saturday morning on the northern edge of a weak mid level ridge (slower timing in regard of previous forecast). Beyond, high pressures located over South Africa will steer the system north northwestwards. Throughout the forecast period, sea surface temperature remain marginal (25 to 26C). Wind-shear should weaken, as system would lie under an upper level anticyclone, and might remain very weak until Friday afternoon. However, very slow motion on weak oceanic heat content might limit system intensity at the moderate tropical storm stage. Northerly then northwesterly vertical wind shear is expected to increase again Friday night and system is therefore expected to weaken slightly before its landfall that is forecast on Sunday between Maputo and Inhambane.

Inhabitants of the potential landfall area should closely monitor the evolution of Irina within the next few days.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #40
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 7 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (991 hPa) located at 29.2S 40.2E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west northwest at 2 knots.

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

Near Gale Force Winds
=============
90 NM radius from the center

Dvorak Intensity:

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

12 HRS: 28.9S 39.4E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 28.7S 38.1E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 28.6S 36.2E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 25.9S 35.7E - 35 knots (Tempête Tropicale Modérée)

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

Irina keeps pn undergoing a westerly wind shear well depicted on SSMIS F17 08MAR 0303 AM UTC and low level circulation center (29.3S 40.3E on 37ghz) is located westward of the upper level one (29.3 40.6E on 85ghz). System drifts slowly west northwestward and is expected to keep on shifting slowly globally west northwestward then westward until Saturday morning on the northern edge of a weak mid level ridge (slower timing in regard on previous forecast). Beyond high pressure located over South Africa will steer the system north northwestward. Throughout the forecast period, sea surface temperature marginal (25-26C). Wind shear should weaken, as system would lie under an upper level anticyclone, and might remain very weak until Friday afternoon. However, very slow motion on weak oceanic heat content might limit system intensity at the moderate tropical storm stage. Northerly then northwesterly wind shear is expected to increase again Friday night and system is therefore expected to weaken slightly before its landfall that is forecast on Sunday between Maputo and Inhambane.

Inhabitants of the potential landfall area should closely monitor the evolution of Irina within the next few days.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL CYCLONE KOJI, CATEGORY ONE (15U)
3:00 PM WST March 8 2012
=============================

At 2:00 PM WST, Tropical Cyclone Koji, Category One (993 hPa) located at 15.9S 90.8E has 10 minute sustained winds of 40 knots with gusts of 55 knots. The low is reported as moving west southwest at 12 knots.

Gale Force Winds
===========
60 NM from the center in northeastern quadrant
90 NM from the center in southeastern quadrant
90 NM from the center in southwestern quadrant
60 NM from the center in the northwestern quadrant

Dvorak Intensity: T3.0/3.0/D0.5/24 HRS

Forecast and Intensity
=======================
12 HRS: 16.4S 88.6E - 40 knots (CAT 1)
24 HRS: 16.8S 86.7E - 45 knots (CAT 1)
48 HRS: 18.4S 82.8E - 45 knots (CAT 2)
72 HRS: 20.4S 81.0E - 35 knots (CAT 1)

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

Curvature has increased in the last three hours and a wrap of 0.7 can be obtained on recent visible imagery. DT of 3.0 is assigned and agrees with MET and PAT. FT and CI are set to 3.0. This is in fairly good agreement with SATCON which assigns 49 knots 1-min mean at 0300 AM UTC. The partial ASCAT pass at 0400 AM UTC does not indicate wind speeds greater than 40 knots. Final intensity estimate is set at 40 knots 10-min mean.

The SSMIS pass at 0214 provided an anchor point for recent fixes and increases the confidence in the analysis position.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast due to an approaching upper trough.

The next warning will be issued by RSMC Reunion at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Outlook
FORECAST WESTERN AUSTRALIA REGION BETWEEN 90E-125E SOUTH OF 10S
11:45 PM WST March 8 2012
=========================

A low is developing south southwest of Bali in the vicinity of 13S 113E. This low is expected to gradually become better defined over the next three days. It is possible that it will develop into a tropical cyclone as early as Sunday but it is more likely to reach tropical cyclone intensity during next week. This low is expected to be located off the Pilbara coast for much of next week with the risk of a coastal impact increasing during the week. Pilbara and Kimberley coastal communities are advised to keep up to date with weather forecasts over the coming week.

Tropical Cyclone Formation Potential
=========================

Friday: Low
Saturday: Low
Sunday: Moderate
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #39
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 7 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (988 hPa) located at 29.3S 40.2E 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
==========
60 NM radius from the center

Near Gale Force Winds
=============
90 NM radius from the center

Dvorak Intensity:

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

12 HRS: 29.3S 39.7E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 29.1S 39.2E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 28.9S 37.4E - 40 knots (Tempête Tropicale Modérée)
72 HRS: 27.4S 35.3E - 35 knots (Tempête Tropicale Modérée)

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

The cloud pattern of Irina has a little deteriorated since 1800z. 1822 PM UTC TRMM 85 ghz microwave shows that system still undergoes a westerly vertical wind shear (CIMSS data 10/12 kt). On the other hand, system is moving very slowly (likely oceanic heat content weakening by cooling of superficial ocean). Without recent ASCAT swath (evening pass no centered) and no pertinent Dvorak analysis, system intensity is difficult to estimate. However, current intensity has been downgraded.

Irina might keep on a westward track by very slowly accelerating until Saturday morning on the northern edge of a weak mid level ridge (slower timing in regard of previous forecast). Beyond that time, high pressures located over South Africa might will steer the system north-northwestward.

throughout the forecast period, sea surface temperature remain marginal (25 to 26C). Wind-shear should weaken, as system would lie under an upper level anticyclone, and might remain very weak until Friday afternoon. However, very slow motion on weak oceanic heat content might limit system intensity at the moderate tropical storm stage. Upper level northerly wind-shear is expected to increase again Friday night and a little weaken the system before its landfall that is forecast on Sunday between Maputo and Inhambane.

inhabitants of the potential landfall area should closely monitor the evolution of Irina within the next few days.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL CYCLONE KOJI, CATEGORY ONE (15U)
9:00 AM WST March 8 2012
=============================

At 8:00 AM WST, Tropical Cyclone Koji, Category One (995 hPa) located at 15.6S 92.2E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The low is reported as moving west southwest at 13 knots.

Gale Force Winds
===========
45 NM from the center in northeastern quadrant
90 NM from the center in southeastern quadrant
90 NM from the center in southwestern quadrant
45 NM from the center in the northwestern quadrant

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

Forecast and Intensity
=======================
12 HRS: 16.3S 89.9E - 35 knots (CAT 1)
24 HRS: 16.7S 87.8E - 40 knots (CAT 1)
48 HRS: 18.0S 83.9E - 50 knots (CAT 2)
72 HRS: 19.9S 81.3E - 40 knots (CAT 1)

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

Locating the system center by enhanced infrared imagery is difficult and there have been very few useful microwave passes overnight so the fix location is uncertain. The ASCAT pass at 1500 PM UTC indicated gales had wrapped a little over halfway around the system center. CIMSS shear analysis indicates around 12 knots of northeasterly shear over the system.

Dvorak DT analysis can only be done with a shear pattern which yields a DT of 3.5 which is inconsistent with the MET of 2.5 and the AMSU/ADT/SATCON estimates. Final Dvorak is based on MET and final intensity is set at 35 knots. The system is named based on the evidence from ASCAT that the gales are wrapping more than half way around the center.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast due to an approaching upper trough.

The next tropical cyclone bulletin from Perth Tropical Cyclone Warning Center on Tropical Cyclone Koji will be issued at 7:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL LOW 15U
3:00 AM WST March 8 2012
=============================

At 2:00 AM WST, Tropical Low (997 hPa) located at 14.8S 93.9E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The low is reported as moving west at 14 knots.

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

Forecast and Intensity
=======================
12 HRS: 15.3S 91.8E - 40 knots (CAT 1)
24 HRS: 15.5S 89.7E - 45 knots (CAT 1)
48 HRS: 16.4S 86.0E - 60 knots (CAT 2)
72 HRS: 18.1S 83.4E - 60 knots (CAT 2)

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

Locating the system center by enhanced infrared imagery is difficult. It seems likely the low level circulation is still located to the east of the convection. CIMSS has around 12 knots of northeasterly shear over the system. The system has shown a developing trend over the last 24 hours. Final Dvorak is now 2.5.

Conditions appear favorable for the system to continue to develop and it is forecast to reach cyclone intensity in 6 to 12 hours time. It should continue to develop over the next 60 hours and then weaken as the system comes under increased shear.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast.

The next tropical cyclone bulletin from Perth Tropical Cyclone Warning Center on Tropical Low 15U will be issued at 1:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #38
FORTE TEMPETE TROPICALE IRINA (11-20112012)
22:00 PM RET March 7 2012
=====================================

At 18:00 PM UTC, Severe Tropical Storm Irina (985 hPa) located at 29.5S 40.4E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving west at 3 knots.

Storm Force Winds
============
30 NM from the center

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

Near Gale Force Winds
=============
100 NM radius from the center, extending up to 120 NM in the western semi-circle

Dvorak Intensity:

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

12 HRS: 29.4S 39.6E - 50 knots (Forte Tempête Tropicale)
24 HRS: 29.2S 38.7E - 50 knots (Forte Tempête Tropicale)
48 HRS: 29.4S 36.2E - 40 knots (Tempête Tropicale Modérée)
72 HRS: 28.1S 34.9E - 35 knots (Tempête Tropicale Modérée)

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

The cloud pattern of Irina has little evolved for the next 6 hours. Last cc satellite imagery showed a 0.7/0.8 curved band, but 1538 PM UTC SSMIS F16 microwave indicates that this band is not continuous. Since yesterday, Dvorak analysis is little pertinent on this system and current intensity is maintained at 50 kt (ASCAT data of this morning). System still seems to undergo a little constraint confirmed by CIMSS data (southwesterly wind shear at 8-9 knots).

Irina is very slowly moving westward and might keep on this track (by a little accelerating) until Saturday morning on the northern edge of a weak mid level ridge. Beyond that time, high pressures located over South Africa might will steer the system north northwestward.

Throughout the forecast period, sea surface temperature remain marginal (25 to 26C. Wind-shear should weaken tomorrow, as system would lie under an upper level anticyclone, and might remain very weak until Friday afternoon. Consequently, current intensity is expected to maintain, maybe even slightly increase, but might remain limited by the weak oceanic heat content. Upper level northerly wind-shear is expected to increase again Friday night and weaken the system before its landfall that is forecast on Sunday between Maputo and Inhambane.

There is still some uncertainty about the final intensity of Irina as it will approach the Mozambican coasts on Sunday. The shear could lessen again Saturday night or Sunday morning and be associated with a slight intensification of the system just before landfall.

Consequently, inhabitants of the potential landfall area should closely monitor the evolution of Irina within the next few days.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL LOW 15U
9:00 PM WST March 7 2012
=============================

At 8:00 PM WST, Tropical Low (997 hPa) located at 14.6S 95.6E has 10 minute sustained winds of 35 knots with gusts of 50 knots. The low is reported as moving west southwest at 12 knots.

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

Forecast and Intensity
=======================
12 HRS: 15.4S 92.8E - 35 knots (CAT 1)
24 HRS: 15.9S 90.2E - 45 knots (CAT 1)
48 HRS: 16.6S 86.4E - 60 knots (CAT 2)
72 HRS: 18.2S 83.3E - 60 knots (CAT 2)

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

With no recent microwave imagery locating the system center by enhanced infrared imagery has proved difficult. It seems likely the low level circulation center is still located to the east of the convection. The system has shown a developing trend over the last 24 hours. Final Dvorak number is now 2.5.

Conditions appear favorable for the system to continue to develop and it is forecast to reach cyclone intensity in 12 to 18 hours time. It should continue to develop over the next 72 hours and then weaken as the system comes under increased shear.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast.

The next tropical cyclone bulletin from Perth Tropical Cyclone Warning Center on Tropical Low 15U will be issued at 19:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #37
FORTE TEMPETE TROPICALE IRINA (11-20112012)
16:00 PM RET March 7 2012
=====================================

At 12:00 PM UTC, Severe Tropical Storm Irina (985 hPa) located at 29.3S 40.7E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving west at 3 knots.

Storm Force Winds
============
30 NM in the southern semi-circle and the northwestern quadrant

Gale Force Winds
==========
65 NM radius from the center, extending up to 70 NM in the south

Near Gale Force Winds
=============
100 NM radius from the center, extending up t0 130 NM in the southwestern quadrant, and up to 140 NM in the northwestern quadrant

Dvorak Intensity:

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

12 HRS: 29.2S 40.0E - 50 knots (Forte Tempête Tropicale)
24 HRS: 29.1S 39.2E - 55 knots (Forte Tempête Tropicale)
48 HRS: 29.3S 36.7E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 28.9S 35.2E - 35 knots (Tempête Tropicale Modérée)

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

The cloud pattern of Irina is improving this afternoon with 0.6 curved band on n19 visible imagery of 1129 AM UTC. A warm spot is seen on latest visible geostationnary imagery. Dvorak estimation still seems to underestimate the real intensity (PGTW and KNES give a CI at 2.5 at 1130z AM UTC associated with 30-35 kt max 10 min winds) and is not used for the intensity assessment. It is based on extrapolation of ASCAT data of this morning.

Irina has begun its westwards turn that should occur at a rather low motion until Saturday morning on the northern edge of a weak mid level ridge. Beyond that time, high pressures located over South Africa might will steer the system north northwestwards.

Throughout the forecast period sea surface temperature remain marginal (25 to 26C). Currently, the wind shear is from the southwest at .It should release from tomorrow to around Friday midday, as system would lie temporarily under an upper level anticyclone. Consequently, additional strengthening is still possible within this time-frame but should remain limited by the weak oceanic heat content. The upper level northerly wind shear should increase Friday night and weaken the system before its landfall that is forecast on Sunday between Maputo and Inhambane.

There is still some uncertainty about the final intensity of Irina as it will approach the Mozambican coasts on Sunday. The shear could lessen again Saturday night or Sunday morning and be associated with some strengthening just before landfall.

Consequently, inhabitants of the potential landfall area should closely monitor the progress of Irina within the next few days.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #36
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 7 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (992 hPa) located at 29.5S 40.8E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving north at 2 knots.

Gale Force Winds
==========
50 NM radius from the center, extending up to 100 NM in the northwestern quadrant and up to 160 NM in the southwestern quadrant

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 80 NM in the northeastern quadrant, up to 160 NM in the northwestern quadrant, and up to 200 NM in the southwestern quadrant

Dvorak Intensity:

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

12 HRS: 29.1S 40.4E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 28.9S 39.6E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 29.1S 37.3E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 29.4S 34.7E - 40 knots (Tempête Tropicale Modérée)

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

Irina still show some tropical characteristics with a well defined warm core seen on AMSU profiles sustained by intermittent burst of deep convection close to the center. On first visible imagery, Irina show a pretty well defined partly exposed low level vortex on the northwestern side of main convection. Current intensity assessment is based on ASCAT data of last night.

The subtropical mid-level anticyclone cell should strengthen somewhat to the south tomorrow. So Irina is expected to resume a westward track by that time. On and after Saturday, high pressures situated over South Africa might steer the system north-northeastward.

Throughout the forecast period sea surface temperature remain marginal (25 to 26C). Upper level environmental conditions are actually rather unfavorable with a 15 knots southwesterly shear, but it should release more clearly tomorrow, as system would lie temporarily under an upper level anticyclone. Consequently, an intensification is likely but should remain limited by the weak oceanic heat content. The upper level northerly wind shear should increase Friday night or Saturday and weaken the system before its landfall that is forecast on Sunday between Maputo and Inhambane.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL LOW 15U
3:00 PM WST March 7 2012
=============================

At 2:00 PM WST, Tropical Low (1000 hPa) located at 14.3S 96.8E has 10 minute sustained winds of 25 knots with gusts of 45 knots. The low is reported as moving west southwest at 11 knots.

Dvorak Intensity: T2.0/2.0/D0.5/24 HRS

Forecast and Intensity
=======================
12 HRS: 15.1S 94.4E - 30 knots (Tropical Low)
24 HRS: 15.8S 91.7E - 40 knots (CAT 1)
48 HRS: 16.5S 87.5E - 55 knots (CAT 2)
72 HRS: 17.9S 84.1E - 65 knots (CAT 3)

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

With no recent microwave imagery locating the system center by visible imagery has proved difficult. It seems likely the low level circulation center is still located to the east of the convection even though shear analyses indicate shear is now below 20 knots from the east. The system has shown a developing trend over the last 24 hours. Final Dvorak has remained at 2.0 during the day.

Conditions appear favorable for the system to continue to develop and it is forecast to reach cyclone intensity in 18 to 24 hours time. It should continue to develop over the next 72 hours and then weaken as the system comes under increased shear.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast.

The next tropical cyclone bulletin from Perth Tropical Cyclone Warning Center on Tropical Low 15U will be issued at 13:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Outlook
FORECAST WESTERN AUSTRALIA REGION BETWEEN 90E-125E SOUTH OF 10S
12:27 PM WST March 7 2012
=========================

A tropical low (15U) was located near 14S 98E at 9am WST Wednesday, about 225 km to the south southeast of Cocos Island and moving steadily west southwest at 19 kilometres per hour. It is likely to develop into a tropical cyclone during Thursday or Friday. On Friday this system is likely to cross 90E and move away from the Western Region. The system is not expected to affect the Cocos Islands.

System #2
-----------

Thunderstorm activity is continuing to increase in tropical maritime parts of the Western Region near the monsoon trough, which currently extends from 14S 98E to 12S 110E to a weak low near 16S 118E. The risk of this low becoming a tropical cyclone increases over the weekend when it is likely to be located in the general vicinity of 15S 115E.

Tropical Cyclone Formation Potential
=======================

Thursday: Low
Friday: Moderate
Saturday: Moderate
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Perth Tropical Cyclone Warning Center
Tropical Cyclone Bulletin
TROPICAL LOW 15U
9:00 AM WST March 7 2012
=============================

At 8:00 AM WST, Tropical Low (1000 hPa) located at 13.9S 97.9E has 10 minute sustained winds of 25 knots with gusts of 45 knots. The low is reported as moving southwest at 10 knots.

Dvorak Intensity: T2.0/2.0/D1.0/24 HRS

Forecast and Intensity
=======================
12 HRS: 14.7S 95.9E - 30 knots (Tropical Low)
24 HRS: 15.5S 93.2E - 35 knots (CAT 1)
48 HRS: 16.2S 88.6E - 55 knots (CAT 2)
72 HRS: 17.4S 85.1E - 65 knots (CAT 3)

Additional Information
=====================
The system has continued to develop overnight with a clear low level center to the east of cold convection. DT is fluctuating as the distance from the low level circulation center to the convection increases and decreases but MET=PAT=FT=2.0.

Conditions appear favourable for the system to continue to develop and it is forecast to reach cyclone intensity in 24 hours time. It should continue to develop over the next 72 hours and then weaken as the system comes under increased shear.

The system is being steered by a mid-level ridge and a general southwestwards movement is expected to continue through until Saturday when a more southerly track is forecast.

The next tropical cyclone bulletin from Perth Tropical Cyclone Warning Center on Tropical Low 15U will be issued at 7:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #35
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 7 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (990 hPa) located at 29.8S 40.8E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving northeast at 7 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 60 NM in the northeastern quadrant, and up to 150 NM in the western semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 100 NM in the northeastern quadrant, and up to 200 NM in the western semi-circle

Dvorak Intensity:

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

12 HRS: 29.3S 40.5E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 29.1S 39.9E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 28.8S 37.6E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 28.9S 34.9E - 40 knots (Tempête Tropicale Modérée)

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

ASCAT data at 06MAR/1937 PM UTC confirm that gale force winds exist in the western semi-circle of the low level circulation which remains asymmetrical. System has now hybrid tropical/subtropical characteristics suggested by available observation data (AMSU cross sections from CIMMS / ASCAT and micro-wave TRMM at 06MAR/1819 PM UTC). For now, the moderate tropical storm stage is maintained.

Within the next 12 hours, the subtropical mid-level anticyclone cell rebuilding southeastward might dictate a westward track to the system up to friday to saturday night. On and after saturday, high pressures situated over south africa might steer the system north-northeastward.

Throughout the forecast period sea surface temperature remain marginal (25 to 26C). Upper level environmental conditions are actually neutral, but a the upper level constraint should release more clearly by tau 24, as system would lie temporarily under an upper level anticyclone. Consequently, system intensity should little fluctuate around the actual intensity within the next 24 hours, and should consolidate on Thursday, but remain limited by the weak oceanic heat content. The upper level northerly wind-shear should increase on Friday and weaken the system before its landfall that is now forecast on Sunday in the bay of Maputo.

Numerical weather prediction models are in rather good agreement for the forecast track.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #34
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 6 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 29.7S 40.3E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving north northeast at 9 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 60 NM in the northeastern quadrant and up to 110 NM in the western semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 100 NM in the northeastern quadrant, up to to 200 NM in the western semi-circle

Dvorak Intensity:

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

12 HRS: 28.9S 40.3E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 28.5S 39.6E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 28.2S 37.8E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 28.7S 35.7E - 40 knots (Tempête Tropicale Modérée)

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

Convection has temporarily reorganized above the low level circulation center during the past 6 hours (cf. SSMIS at 15.51 PM UTC), but remains fluctuating.

Within the next 12 hours, the subtropical mid-level anticyclone cell situated in the west is going to steer the system globally northward. Beyond, rebuilding east southeastward high pressures might dictate a westward track up to Friday to Saturday night. On Saturday and after, high pressures situated over south Africa might steer the system northward.

Upper level environmental conditions seem to improve slightly for tonight (weakening of relative vertical wind shear), but a the upper level constraint should release more clearly by 18 to 24 hours. However sea surface temperature remain marginal (25 to 26C). Consequently, within these neutral actual conditions, becoming slightly more favorable on Wednesday evening, system intensity should little fluctuate around the actual intensity within the next 24 hours, and should consolidate during Wednesday night, up to Friday. On and after, Saturday system should weaken with strengthening northerly wind-shear.

Numerical weather prediction models are in good agreement for the forecast track (now including ECMWF for the track at the end of forecast period). However, ECMWF is the only one that deepens the system during its northward track. Now, is not the option chosen by RSMC.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #33
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 6 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 30.3S 39.3E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving east northeast at 8 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 60 NM in the southeastern quadrant, and up to 160 NM in the western semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 80 NM in the southeastern quadrant, up to 250 NM in the southwestern quadrant, and up to 280 NM in the northwestern quadrant

Dvorak Intensity:

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

12 HRS: 29.5S 40.0E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 28.7S 40.3E - 35 knots (Tempête Tropicale Modérée)
48 HRS: 27.9S 38.5E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 28.5S 36.0E - 40 knots (Tempête Tropicale Modérée)

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

The low level center is totally exposed with a very well vortex. Convection is weak and very fluctuating in the southern part of the system. 0615 AM UTC ASCAT swath shows winds exceeding 45 knots in the western semi-circle. Dvorak analysis is not pertinent for this system, but no element indicates subtropical or extratropical characteristics (phasis diagrams and CIMSS AMSU-A cross sections). So, moderate tropical storm classification is maintained.

Within the next 24 hours, the subtropical mid-level anticyclone cell situated in the west is going to steer the system toward the northeast. Beyond, rebuilding east-southeastward high pressures might dictate a westward track up to Friday or Saturday. Intensity forecast is rather problematic during the same time. Tomorrow, upper level environmental conditions might improve (weakening vertical wind shear), but sea surface temperature remain marginal (25 to 26C). After a temporary weakening tonight and tomorrow, system should slightly re-intensify up to Friday.

From Saturday, high pressures situated over south Africa might steer the system northward. It is expected that system will weaken again with strengthening northerly wind-shear.

Numerical weather prediction models are in good agreement for the forecast track (now including ECMWF for the track at the end of forecast period). However, ECMWF is the only one that deepens the system during its northward track. Now, is not the option chosen by RSMC.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Tropical Cyclone Warning Center Perth
Tropical Cyclone Outlook
1:39 PM WST March 6 2012
=========================

A tropical low was located near 12S 101E at 9am WST Tuesday, about 450 km to the east of Cocos Island and moving steadily westwards. The low is expected to continue moving in a generally west to southwest direction over the next few days and is expected to move south of Cocos Island during Wednesday. At this stage it is not expected to affect the Cocos Islands. It may develop into a tropical cyclone late on Wednesday or more likely on Thursday or Friday. By Friday this system is likely to be near 90E.

Tropical Cyclone Formation Potential
=======================

Wednesday: Moderate
Thursday: High
Friday: High

System #2
-----------

Thunderstorm activity is continuing to increase in tropical maritime parts of the Western Region near the monsoon trough, currently approximately located along latitude 12S. A low is likely to develop between longitudes 110E and 120E on Thursday or Friday. The risk of this system becoming a tropical cyclone increases over the weekend.

Tropical Cyclone Formation Potential
=======================

Wednesday: Low
Thursday: Low
Friday: Moderate
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #31
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 6 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (992 hPa) located at 30.4S 37.9E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving east at 8 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 160 NM in the western semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 280 NM in the northwestern sector and up to 250 NM in the southwestern sector

Dvorak Intensity: T2.5/3.0/W0.5/24 HRS

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

12 HRS: 30.0S 39.0E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 28.9S 39.7E - 30 knots (Depression Tropicale)
48 HRS: 28.2S 38.8E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 28.6S 37.0E - 45 knots (Tempête Tropicale Modérée)

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

System is undergoing a westerly vertical wind shear and cool sea surface temperature (about 25.5 to 26C). Wind field is very disymetrique due to the strong gradient in the western semi-circle with the subtropical highs in the southwestern of the system (ASCAT at 1859 PM UTC). Since the last 12 hours, the track is eastwards in relation with the subtropical anticyclone cell growing in the southwest of the system. Within the next 5 days, system should make a complete loop in the anti-clockwise way and track again eastwards at the end of the forecast range. Indeed it should remain north of the subtropical high pressures, and remain out of the influence of the mid-latitudes trough transiting in its south at the end of the week. The present forecast track is a consensus of the available numerical weather prediction models. On this track, on Thursday and Friday, system should encounter more favorable upper level environmental conditions (weakening vertical wind shear). However sea surface temperature should remain marginal, throughout the forecasting period.

The forecast trend is a weakening of the intensity within the next 36 hours, and then a possible slow regeneration on and after Thursday.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #30
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 5 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 30.4S 37.0E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving east at 9 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 50 NM in the western semi-circle

Near Gale Force Winds
=============
70 NM radius from the center, extending up to 130 NM in the northwestern sector and up to 180 NM in the southwestern sector

Dvorak Intensity: T3.0/3.0/W0.5/24 HRS

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

12 HRS: 29.9S 37.9E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 29.3S 38.3E - 30 knots (Depression Tropicale)
48 HRS: 28.3S 37.7E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 29.0S 35.5E - 45 knots (Tempête Tropicale Modérée)

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

The center of the low level circulation is always located near the northern edge of the residual convection. System is struggling against the upper level northwesterly vertical wind shear and cool sea surface temperature (about 25.5C according to ECMWF analysis).

Since the last 12 hours, the track has turned southeastward to east in relation with the subtropical anticyclone cell growing in the southwest of the system. Within the next 5 days, system should make a complete loop in the anti-clockwise way and track again eastwards at the end of the forecast range. Indeed it should remain north of the subtropical high pressures, and remain out of the influence of the mid-latitudes trough transiting in its south at the end of the week.

The present forecast track is a consensus of the available numerical weather prediction models.

On this track, on and after Thursday, system should encounter more favorable upper level environmental conditions (weakening vertical wind shear). However sea surface temperature should remain marginal, throughout the forecasting period. The forecast trend is a weakening of the intensity within the next 36 hours, and then a possible slow regeneration on and after Wednesday afternoon.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #29
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 5 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 30.5S 35.6E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving southeast at 6 knots.

Gale Force Winds
==========
40 NM radius from the center, extending up to 50 NM in the western semi-circle

Near Gale Force Winds
=============
70 NM radius from the center, extending up to 130 NM in the northwestern sector and up to 180 NM in the southwestern sector

Dvorak Intensity: T3.0/3.0/W0.5/12 HRS

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

12 HRS: 30.4S 36.8E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 29.7S 37.6E - 30 knots (Depression Tropicale)
48 HRS: 28.2S 37.5E - 30 knots (Depression Tropicale)
72 HRS: 28.7S 35.8E - 40 knots (Tempête Tropicale Modérée)

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

The low level circulation is now partially exposed northwest from the residual convection. System is struggling against the upper level northwesterly vertical wind shear and cool sea surface temperature (about 25C according to ECMWF analysis). Since the last 12 hours, the track has turned southeastward in relation with the subtropical anticyclone cell growing in the southwest of the system. Within the next 5 days, system should make a complete loop in the anti-clockwise way and track again eastward at the end of the forecast range. Indeed it should remain north of the subtropical high pressures, and remain out of the influence of the mid-latitudes trough transiting in its south at the end of the week.

The present forecast track is a consensus of the available numerical weather prediction models.

On this track, on and after Thursday, system should encounter more favorable upper level environmental conditions (weakening vertical wind shear). However sea surface temperature should remain marginal, throughout the forecasting period. The forecast trend is a weakening of the intensity within the next 48 to 60 hours, and then a possible regeneration on and after Thursday.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Tropical Cyclone Warning Center Perth
Tropical Cyclone Outlook
2:00 PM WST March 5 2012
=========================

Thunderstorm activity is continuing to increase in tropical maritime parts of the Western Region near the monsoon trough, currently located along 11-12S. A weak low lies near 13S 106E and while not likely to develop during Tuesday, the low will move slowly west with computer models indicating that the low will develop as it moves west, possibly reaching tropical cyclone strength near 14S 94E late Wednesday or Thursday.

Tropical Cyclone Formation Potential
========================

Tuesday: Moderate
Wednesday: High
Thursday: High
Member Since: May 24, 2006 Posts: 51 Comments: 45581
re-edit post.

At 6:00 AM UTC, Moderate Tropical Storm Irina (986 hPa) located at 30.2S 35.3E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving east southeast at 11 knots.
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #28
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 5 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (986 hPa) located at 30.2S 35.3E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving east southeast at 11 knots.

Gale Force Winds
==========
55 NM radius from the center, extending up to 85 NM in the western semi-circle

Near Gale Force Winds
=============
80 NM radius from the center, extending up to 150 NM in the western semi-circle

Dvorak Intensity: T3.0/3.5/W0.5/12 HRS

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

12 HRS: 29.8S 36.5E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 29.3S 37.5E - 35 knots (Tempête Tropicale Modérée)
48 HRS: 27.5S 38.0E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 27.6S 36.6E - 50 knots (Forte Tempête Tropicale)

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

Irina began a turn eastward (cf. F16 at 03.36 AM UTC). Clouds tops are warming. System is interacting with the mid latitudes trough. It is struggling with the upper level northwesterly vertical wind shear and cool sea surface temperature (of the order of 25.5S according to ECMWF analysis).

The track has turn eastward in relation with the subtropical anticyclone cell growing in its southwest. System should make a complete loop in the anti-clockwise way under the influence of the aforementioned anticyclonic subtropical cell. At the end of the forecast range, it should track southwestward again in direction of a mid-latitudes trough. The present forecast track is a consensus of the available numerical weather prediction models which are in rather good agreement and do not forecast any more the landfall on the African coasts. As it would track northward, on and after Wednesday, system should encounter more favorable upper level environmental conditions (weakening vertical wind shear). However sea surface temperature should remain marginal, at least by the end of the forecast range. The forecast trend is a weakening of the intensity within the next 36 hours, and then a possible regeneration on and after Wednesday.

All inhabitants along African coastline between 25.0S and 30.0S are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #27
FORTE TEMPETE TROPICALE IRINA (11-20112012)
4:00 AM RET March 5 2012
=====================================

At 0:00 AM UTC, Severe Tropical Storm Irina (979 hPa) located at 29.8S 34.7E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving south southeast at 11 knots.

Storm Force Winds
================
15 NM radius from the center

Gale Force Winds
==========
30 NM radius from the center, extending up to 70 NM in the southwestern quadrant, and up to 90 NM in the southeastern quadrant

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 110 NM in the southwestern quadrant, and up to 150 NM in the southeastern quadrant

Dvorak Intensity: T35/3.5/D1.0/12 HRS

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

12 HRS: 30.2S 35.5E - 50 knots (Forte Tempête Tropicale)
24 HRS: 29.2S 36.6E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 27.2S 37.1E - 30 knots (Depression Tropicale)
72 HRS: 26.0S 35.2E - 50 knots (Forte Tempête Tropicale)

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

Irina has accelerated south southeastwards over the past 18 hours. Relative northerly wind shear is therefore weakening aloft and despite a weakened oceanic heat content, system organization has rapidly improve from 1200z to 1800z (refer to SSMI F15 04MAR/1402 PM UTC and SSMIS F16 04MAR/1617 PM UTC). Meteosat7 and msg2 infrared imagery shows an eye between 1630 PM and 1700 PM UTC. Convection organizes now in curved band pattern and between 1800 PM and 0000 AM UTC, intensity keeps on stabilizing (refer to TRMM 1930 PM UTC). In relationship with the large extension of the strongest winds southward, a 3 meters to 5 meters cyclonic swell is always battering the African coastlines from 26.0S to 34.0S within the next 24 hours. Within the next 48 hours, system is expected to progressively undergo the steering influence of the high subtropical pressures rebuilding in the southwest and is therefore expected to recurve left-hand. Despite its expected northeastwards motion, it keeps on shifting over marginal oceanic content and trend is therefore to a regular weakening intensity. From Wednesday 07, environment should progressively improve (rising sea surface temperature and upper level divergence, weak wind shear) and system is expected to continue its left-hand loop motion to finally adopt a globally westwards motion, therefore intensifying. This track will bring Irina back closer to the African coastline.

A landfall on Thursday 08 or Friday 09 remains however hypothetical as a new weakness in the subtropical belt should steer Irina southwards again (refer to ECMWF 0000 AM and 1200 PM UTC runs).

All inhabitants along African coastline between 23.0S and 30.0S are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #26
FORTE TEMPETE TROPICALE IRINA (11-20112012)
22:00 PM RET March 4 2012
=====================================

At 18:00 PM UTC, Severe Tropical Storm Irina (979 hPa) located at 28.5S 34.5E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving south southeast at 12 knots.

Storm Force Winds
================
15 NM radius from the center

Gale Force Winds
==========
25 NM radius from the center, extending up to 30 NM to 40 NM in the southern semi-circle

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 80 NM in the southwestern quadrant, and up to 150 NM in the southeastern quadrant

Dvorak Intensity: T3.5/3.5/D0.5/12 HRS

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

12 HRS: 29.9S 35.0E - 50 knots (Forte Tempête Tropicale)
24 HRS: 29.6S 36.3E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 27.4S 37.9E - 30 knots (Depression Tropicale)
72 HRS: 25.9S 37.2E - 50 knots (Forte Tempête Tropicale)

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

Irina has accelerated southwards over the past 12 hours. Relative northerly wind shear is therefore weakening aloft and despite a weakened oceanic heat content, deep convective activity has clearly strengthened.

System organization has rapidly improve (refer to SSMI f15 04/1402z) and Meteosat7 and msg2 infrared imagery shows a warm point since 1630 PM UTC. At 1700 PM UTC, instantaneous Dvorak analysis has reached up to 5.0 but current fix intensity is an average over the last 06 hours. In relationship with the large extension of the strongest winds southward, a 3 meters to 4 meters cyclonic swell is always battering the African coastlines from 26s to 33s within the next 24 hours. Within the next 48 hours, system is expected to progressively undergo the steering influence of the high subtropical pressures rebuilding in the southwest and is therefore expected to continue its left-hand loop motion. Despite its expected northern motion, it keeps on shifting over marginal oceanic content and trend is therefore to a regular weakening intensity. From Wednesday 07, environment should progressively improve (rising sea surface temperature and upper level divergence, weak wind shear) and system is expected to continue its left-hand loop motion to finally adopt a globally westwards motion, therefore intensifying. This track will bring Irina back closer to the African coastline. A landfall Friday 09 remains however hypothetical as a new weakness in the subtropical belt should steer Irina southwards again.

All inhabitants along African coastline between 23s and 30s are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #25
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 4 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 27.2S 34.1E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving south at 8 knots.

Gale Force Winds
==========
25 NM radius from the center extending up to 30 NM to 40 NM in the southern semi-circle

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 80 NM in the southwestern quadrant and up to 150 NM in the southeastern quadrant

Dvorak Intensity: T2.5/3.0/W1.0/18 HRS

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

12 HRS: 29.0S 34.2E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 29.4S 35.2E - 30 knots (Depression Tropicale)
48 HRS: 27.3S 36.5E - 30 knots (Depression Tropicale)
72 HRS: 25.6S 35.8E - 35 knots (Tempête Tropicale Modérée)

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

Associated convection suffer from the combined effects of marginal sea surface temperature and upper level northerly constraint. Convection over the center remains weak and a curved band try to rebuilt in the southern semi-circle. The system is expected to go on weakening.

The system is now tracking southwards accelerating. All guidance are now in agreement to make Irina shift southwards on the western edge of the the subtropical high pressures located south of Madagascar.

Monday, the system is expected to gradually recurve southeastwards towards a polar trough transiting between the two subtropical high pressures areas.The one located to the east is moving eastwards away and a new one is rebuilding to the southwest of Irina. Tuesday and after, Irina could track northwards then northwestwards under the steering influence of this rebuilding subtropical highs.

Along Irina's southwards motion, environmental conditions are neutral to less favorable( northerly upper level constraint then westerly until Wednesday, marginal sea surface temperature) and the system is therefore expected to go on weakening.

On and after Wednesday 07, as system recurves northwestwards, environmental conditions could become back favorable for a slight intensification. There is a strong uncertainty on this aspect of the forecast and an alternate scenario that may become the main one later on, could be that the system will not recovered from the expected deterioration of environmental conditions on Monday and Tuesday and could then track northwestwards as a weakening system.

All inhabitants along African coastline between 23.0s and 30.0s are still invited to closely monitor the progress of Irina.


The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #24
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 4 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (987 hPa) located at 26.3S 33.9E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving west southwest at 5 knots.

Gale Force Winds
==========
30 NM radius from the center, extending up to 60 NM to 80 NM in the southern semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 150 NM in the southwestern quadrant, and up to 350 NM in the southeastern quadrant

Dvorak Intensity: T3.0/3.4/W0.5/12 HRS

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

12 HRS: 27.8S 34.0E - 45 knots (Tempête Tropicale Modérée)
24 HRS: 29.2S 34.4E - 45 knots (Tempête Tropicale Modérée)
48 HRS: 28.4S 35.8E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 26.8S 35.4E - 35 knots (Tempête Tropicale Modérée)

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

The microwave imagery SSMI of 0134 AM UTC shows a southwards tilt, confirmed by SSMIS of 0358. The system has recurved southwestwards slowing down. All guidance are now in agreement to make Irina shift southwards later today on the western edge of the the subtropical high pressures located south of Madagascar.

Associated with the large fetch in the southern semi-circle, a 4 meters to 6 meters cyclonic swell is battering the African coastlines from 24.0s to 33.0s and should persist today.

Monday, the system is expected to gradually recurve southeastwards towards a polar trough transiting between the two subtropical high pressures areas.The one located to the east is moving eastwards away and a new one is rebuilding to the southwest of Irina.

Tuesday and after, Irina could track northwards then westwards under the steering influence of this rebuilding subtropical highs.

Along Irina's southwards motion, environmental conditions are neutral to less favorable( northerly upper level constraint, marginal sea surface temperature but improving upper level divergence to the south) and the system is therefore not expected to intensify or even waken slightly.

Tuesday 06, upper level conditions should deteriorate with an increase in westerly shear.

On and after Wednesday 07, as system recurves northwestwards then westwards, environmental conditions could become back favorable for intensification. There is a strong uncertainty on this aspect of the forecast and an alternate scenario that may become the main one later on, could be that the system will not recovered from the expected deterioration of environmental conditions on Tuesday and could then track northwestwards as a weakening system.

All inhabitants along African coastline between 23.0s and 30.0s are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #23
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 4 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (985 hPa) located at 25.7S 34.3E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving west at 3 knots.

Gale Force Winds
==========
30 NM radius from the center, extending up to 60 NM to 70 NM in the southern semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 220 NM in the southwestern quadrant, and up to 350 NM in the southeastern quadrant

Dvorak Intensity: T3.0/3.5/D0.5/24 HRS

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

12 HRS: 27.5S 34.4E - 45 knots (Tempête Tropicale Modérée)
24 HRS: 29.3S 35.1E - 45 knots (Tempête Tropicale Modérée)
48 HRS: 29.7S 37.1E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 27.6S 37.5E - 35 knots (Tempête Tropicale Modérée)

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

The eye feature seen on 85-91 ghz microwave imagery is not consolidating. AMSUB METOP imagery show this feature located to the south of the estimated center given by the ASCAT winds. The system is still on its westwards motion and continue to slow down. All guidance are now in agreement to make Irina shift southwards later today on the western edge of the the subtropical high pressures located south of Madagascar. If Irina maintain its current motion, it could make landfall near Maputo later today. This possibility, suggested by none of the guidance, appears as a very low probability event.

Associated with the large fetch in the southern semi-circle, a 4 meters to 6 meters cyclonic swell is battering the African coastlines from 24.0s to 33.0s and should persist today.

Monday, the system is expected to gradually recurve southeastwards towards a polar trough transiting between the two subtropical high pressures areas.The one located to the east is moving eastwards away and a new one is rebuilding to the southwest of Irina.

Tuesday and after, Irina could track northwards then westwards under the steering influence of this rebuilding subtropical highs.

Along Irina's southwards motion, environmental conditions are neutral (improving upper level divergence to the south, marginal ea surface temperature) and the system is therefore not expected to intensify significantly.

Tuesday, upper level conditions should deteriorate with an increase in westerly shear.

On and after Wednesday, as system recurves northwestwards then westwards, environmental conditions could become back favorable for intensification. There is a strong uncertainty on this aspect of the forecast and an alternate scenario that may become the main one later on, could be that the system will not recovered from the expected deterioration of environmental conditions on Tuesday and could then track northwestwards as a weakening system.

All inhabitants along African coastline between 23.0s and 30.0s are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #22
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 3 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (983 hPa) located at 25.7S 34.6E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving west at 6 knots.

Gale Force Winds
==========
30 NM radius from the center extending up to 50 NM in the northwestern quadrant, and up to 70 NM in the southern semi-circle

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 60 NM in the northwestern quadrant, up to 220 NM in the southwestern quadrant, and up to 320 NM in the southeastern quadrant

Dvorak Intensity: T3.5/3.5/D 0.5/6 HRS

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

12 HRS: 26.3S 34.4E - 50 knots (Forte Tempête Tropicale)
24 HRS: 28.4S 34.7E - 45 knots (Tempête Tropicale Modérée)
48 HRS: 30.2S 36.7E - 40 knots (Tempête Tropicale Modérée)
72 HRS: 28.1S 38.1E - 40 knots (Tempête Tropicale Modérée)

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

Irina is strengthening a bit as seen on mw imagery early this evening with now an eye feature seen on 85 GHZ channel. However latest SSMIS of 1630 PM UTC show that this feature has not improved yet. The system is still on its westwards motion but has significantly slow down. Tomorrow, Irina is expected to shift southwards on the western edge of the the subtropical high pressures located south of Madagascar.

The northern edge of Irina's inner core has begun to affect the Mozambican coasts near Chidenguele since this evening. An active spiral band is also affecting coastal areas between Xai-Xai (Mozambique) northward to northern vicinity of Richard's Bay southward (extreme northeastern coasts of South Africa) including capital of Mozambique Maputo.Those heavy rains accompanied with strong gusts should persist persist tonight and also spread over portions of eastern Swaziland. Associated with the large fetch in the southern semi-circle, a 4 meters to 6 meters cyclonic swell is battering the African coastlines from 24.0s to 33.0s and should persist tomorrow.

Monday, the system is expected to gradually recurve southeastwards towards a polar trough transiting between the two subtropical high pressures areas.The one located to the east is moving eastwards away and a new one is rebuilding to the southwest of Irina.

Tuesday and after, Irina could track northwards then westwards under the steering influence of this rebuilding subtropical highs.

Along Irina's southwards motion, environmental conditions are neutral (lack of low level inflow, marginal sea surface temperature) and temporarily unfavorable (westerly wind shear constraint is expected on Monday the 05th and Tuesday the 06th), system is therefore not expected to intensify and should temporarily weaken.
On and after Wednesday the 07th, as system recurves northwestwards then westwards, environmental conditions become back favorable for intensification.

RSMC official forecast consider this scenario as the most likely (shown by ECMWF, ARPEGE, and NOGAPS numerical weather prediction models). Latest numerical weather prediction outputs suggest that the alternative possibility of a landfall later tonight or tomorrow is less likely ... But cannot not be ruled out at this time!!

Consequently, all inhabitants along African coastline between 23.0s and 30.0s are still invited to closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
RSMC Reunion
Tropical Cyclone Outlook
16:00 PM UTC March 3 2012
======================

Tropical disturbance 12R (12-20112012) centred at 0600 AM UTC near 16.0S 64.0E has been now considered to be dissipated.

No warning related to the system nr12 will be issued unless regeneration
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #21
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 3 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (986 hPa) located at 25.8S 35.5E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving southwest at 8 knots.

Gale Force Winds
==========
30 NM radius from the center, extending up to 45 NM in the northwestern quadrant, and up to 70 NM in the southern semi-circle

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 60 NM in the northwestern quadrant, up to 220 NM in the southwestern quadrant, and up to 320 NM in the southeastern quadrant

Dvorak Intensity: T3.0/3.0/D0.5/6 HRS

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

12 HRS: 26.5S 34.6E - 50 knots (Forte Tempête Tropicale)
24 HRS: 28.4S 34.2E - 50 knots (Forte Tempête Tropicale)
48 HRS: 30.5S 36.0E - 50 knots (Forte Tempête Tropicale)
72 HRS: 29.0S 38.2E - 50 knots (Forte Tempête Tropicale)

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

Both convective and winds field structures remains asymmetric with strongest winds extending far away in the southern semi-circle due to the gradient effect with subtropical high pressures. Winds extension has been recalibrated thanks to 0716 AM UTC ASCAT swath. Within the next 24 hours, Irina is expected to shift southwestwards then southwards on the western edge of the the subtropical high pressures transiting south of Madagascar. In relationship with the large fetch in the southern semi-circle, a 4 meters to 6 meters cyclonic swell is expected to threaten African coastlines from 24.0s to 33.0s within the next 24 hours. From 24-48 hours, system is expected to progressively recurve southeastwards towards a polar trough transiting between the two subtropical high pressures areas.

The first aforementioned one is moving eastwards away and a new one is rebuilding in the southwest. Beyond 48 hours, Irina is expected to make a loop left-hand northwards then westwards under the steering influence of this rebuilding subtropical highs. Within the southwards motion, environmental conditions are neutral (lack of low level inflow, marginal sea surface temperature) and temporarily unfavorable (westerly wind shear constraint is expected on Monday 5th and Tuesday 6th), system is therefore not expected to intensify and should temporarily weaken. On and after Wednesday 7th, as system recurves northwestwards then westwards, environmental conditions become back favorable for intensification. RSMC official forecast consider this scenario as the most likely (purposed by ECMWF, ARPEGE and NOGAPS numerical weather prediction models).

An alternative scenario exists however to forecast a globally westwards track towards the Mozambique coastline and therefore an expected landfall next night or Sunday (GFS, ALADIN and GFDN numerical weather prediction models option). A rather strong uncertainty keeps on existing related to the official forecast. A landfall over Mozambique coastline at short or medium range can not be excluded.

Despite current forecast, all inhabitants along African coastline between 23.0s and 30.0s are invited to closely monitor the evolution of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #20
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 3 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (990 hPa) located at 24.9S 36.7E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west at 10 knots.

Gale Force Winds
==========
30 NM radius from the center, extending up to 120 NM in the southern semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 220 NM in the southwestern quadrant, and up to 250 NM in the southeastern quadrant

Dvorak Intensity: T2.5/3.0/S0.0/12 HRS

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

12 HRS: 25.2S 34.8E - 35 knots (Tempête Tropicale Modérée)
24 HRS: 26.4S 34.7E - 30 knots (Depression Tropicale)
48 HRS: 29.8S 35.7E - 50 knots (Forte Tempête Tropicale)
72 HRS: 28.4S 37.1E - 60 knots (Forte Tempête Tropicale)

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

Both convective and winds field structure remains asymmetric with strongest winds extending far away in the southern semi-circle due to gradient effect with subtropical high pressures.

Within the next 12 hours, the subtropical high pressures located in the south are going to steer the system on a westward track.

Two divergent scenario are then purpose by available numerical weather prediction models.

- first one the following numerical weather prediction models , GFS, ALADIN and GFDN keep on forecasting a globally westwards track towards the Mozambique coastline and therefore an expected landfall late Saturday or early Sunday.
- second one , other numerical weather prediction models, ARPEGE, CEP, NOGAPS and ukmo diverge on the forecast system track with a deceleration and southwards recurve motion in relationship with a transiting trough in the south and a new barometric col situation then from Monday or Tuesday system should take a northward track with high pressures going away eastward and a westward rebuilding ridge. Spread of ECMWF ensemble members is very large at these range.

RSMC official forecast is close to this second scenario, but uncertainty is very important. Intensity forecast is also not obvious on this track. During southward track period, moderate wind shear persists, sea surface temperature are more and more cool but good poleward outflow should develop. Within northward track period, wind shear decreases and sea surface temperature increase. It is possible that system will re-intensify during this last phase.

There is an important uncertainty for this scenario proposed by our RSMC. A landfall remains not excluded within next night and then a weakening over Mozambique.

Despite current forecast, all inhabitants along the Mozambican coasts between Maputo and Inhambane should closely monitor the evolution of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #11
PERTURBATION TROPICALE 12-20112012
10:00 AM RET March 3 2012
==============================

At 6:00 AM UTC, Tropical Disturbance 12 (1000 hPa) located at 16.0S 64.0E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving east northeast at 5 knots.

Dvorak Intensity: T2.0/2.0/D0.5/18 HRS

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

12 HRS: 18.5S 65.1E - 30 knots (Depression Tropicale)
24 HRS: 21.2S 66.4E - 35 knots (Depression Extratropicale)
48 HRS: 22.7S 61.6E - 35 knots (Depression Extratropicale)
72 HRS: 24.6S 57.0E - 30 knots (Depression Extratropicale)

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

Partially covered 0531 AM UTC ASCAT swath show an elongated low level circulation and a low level circulation center difficult to localize. Water vapor imagery show that an upper level trough is digging and getting closer to the south. Ahead of the northwesterly jet associated with the trough, upper level divergence is better and enhanced a strong thunderstorm activity in the southeastern quadrant. Given the current poor organization and the fact that the shear should increase today ; significant strengthening (up to the moderate tropical storm level) seems to be a low probability event. According to the latest guidance, a deepening of this system is expected within next few days night but associated with baroclinic process (interaction with the upper level trough, intrusion of dry air by the western and northern sectors). An hybrid or extratropical structure is likely by that time.

Sunday, the system should sharply curved westwards on the northern side of the subtropical ridge. A weakening trend is anticipated by that time within an unfavourable environment (strong northerly shear, less baroclinic forcing).

Rodrigues island is currently located more than 200 km to the south west of an heavy rainfall area associated with the disorganised convective mass of this system. These precipitations do not get closer of the island at this time. On the forecast track, heavy rains should pass to the east and southeast of the island. However a small variation in track could bring this heavy rains over the island ... consequently inhabitants in rodrigues island should continue to monitor the progress of weather conditions according to their national weather services.

Current intensity does not justify issuance of regular numbered warnings.
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #19
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
4:00 AM RET March 3 2012
=====================================

At 0:00 AM UTC, Moderate Tropical Storm Irina (990 hPa) located at 25.4S 37.6E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west southwest at 13 knots.

Gale Force Winds
==========
30 NM radius from the center extending up to 120 NM in the southern semi-circle

Near Gale Force Winds
=============
60 NM radius from the center, extending up to 220 NM in the southwestern quadrant, and up to 250 NM in the southeastern quadrant

Dvorak Intensity: T2.5/3.0/S0.0/12 HRS

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

12 HRS: 25.3S 35.9E - 45 knots (Tempête Tropicale Modérée)
24 HRS: 25.6S 35.0E - 40 knots (Tempête Tropicale Modérée)
48 HRS: 28.6S 35.0E - 40 knots (Tempête Tropicale Modérée)
72 HRS: 30.2S 37.4E - 40 knots (Tempête Tropicale Modérée)

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

On latest ir satellite imagery, system shows a curved band wrapping on 0.5 lap. 1800 PM UTC CIMSS data suggest that wind shear has very slightly decrease. Winds field is still asymmetric with strongest winds extending far away in the southern semi-circle due to gradient effect with subtropical high pressures.

Within the next 12-18 hours, the subtropical high pressures situated in the south are going to steer the system on a westward track. A slight intensification is possible with weakening wind shear.

From Saturday evening, numerical weather prediction models diverge on the forecast system track. American models confirm a westward track with a landfall over Mozambique on Sunday. ECMWF and ARPEGE forecast a deceleration and southward recurve with a trough transiting in the south and a new barometric col situation.

Up to Monday, ECMWF suggests a southward then southeastward track towards the low-mid level trough and with the steering influence of high pressures situated in the east. Beyond, system should take a northward track with high pressures going away eastward and a westward rebuilding ridge. ECMWF ensemble runs are very dispersed at these tau. RSMC official forecast is close to deterministic ECMWF, but uncertainty is very important.

Intensity forecast is not evident on this track. During southward track period, moderate wind shear persists, sea surface temperature are more and more cool but good poleward outflow should develop. Within northward track period, wind shear decreases and sea surface temperature increase. It is possible that system will re-intensify during this last phase.

There is an important uncertainty for this scenario proposed by ECMWF. A definitive landfall is still possible on Sunday and then a rapid weakening inland over Mozambique.

Despite current forecast, all interest along the Mozambican coasts between Maputo and Inhambane should closely monitor the evolution of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #18
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 2 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 24.8S 38.9E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving west southwest at 12 knots.

Gale Force Winds
==========
20 NM radius from the center, extending up to 30 NM in the northeastern quadrant and up to 120 NM in the southern semi-circle

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 75 NM in the northeastern quadrant, up to 200 NM in the southwestern quadrant, and up to 250 NM in the southeastern quadrant

Dvorak Intensity: T2.5/3.0/W0.5/12 HRS

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

12 HRS: 24.9S 36.4E - 45 knots (Tempête Tropicale Modérée)
24 HRS: 24.9S 35.2E - 45 knots (Tempête Tropicale Modérée)
48 HRS: 25.6S 34.4E - 50 knots (Forte Tempête Tropicale)
72 HRS: 25.8S 33.9E - 50 knots (Forte Tempête Tropicale)

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

System has little evolved for the next 6 hours. 1509 PM UTC SSMIS F17 shows a low level circulation center located north of the convection existing in the southern part of the system. Irina still undergoes a moderate northerly to north-westerly wind shear.

Within the next 24 hours, the subtropical high pressures situated in the south are going to steer the system on a west southwestward then westward track.

On Sunday, with a trough transiting in the south and a new barometric col situation, system should temporary track southward. This tendency is now according to latest ECMWF deterministic and ensemble outputs.

Now, environmental conditions are not very good. Sea surface temperature favorable and established poleward outflow, but persistent moderate northerly to northwesterly constraint. This constraint should abate tomorrow. So,Irina is expected to intensify and could make a landfall or pass very close to the Mozambique coastline at a stronger intensity on Saturday night, south of Inhambane.

On Sunday, it should move away from the coast and stay a bit longer expected over seas. Irina could a little strengthen and make a come back towards the coast Tuesday as the subtropical ridge should rebuild to its south.

A great uncertainty exists for this scenario proposed by ECMWF runs. A definitive landfall is possible on Sunday and then a rapid weakening inland over the Mozambique.

All interest along the Mozambican coasts between Maputo and Inhambane should closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #10
PERTURBATION TROPICALE 12-20112012
16:00 PM RET March 2 2012
==============================

At 12:00 PM UTC, Tropical Disturbance 12 (1002 hPa) located at 16.5S 63.1E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving south southwest at 6 knots.

Dvorak Intensity: T1.5/1.5/W0.5/24 HRS

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

12 HRS: 17.3S 63.4E - 25 knots (Perturbation Tropicale)
24 HRS: 18.7S 64.2E - 25 knots (Perturbation Tropicale)
48 HRS: 22.0S 65.1E - 40 knots (Tempête Tropicale Modérée)
72 HRS: 23.0S 61.3E - Depression se Comblant

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

The system show an ill-defined organization with a low level center very difficult to localize to the north of the main convective activity.

Water vapor imagery show that an upper level trough is digging and getting closer to the south. Ahead of the northwesterly jet associated with the trough, upper level divergence is better and enhanced a strong thunderstorm activity in the southeastern quadrant. Given the current poor organization and the fact that the shear should increase as soon as tomorrow; significant strengthening (up to the moderate tropical storm level) seems to be a low probability event.

According to the latest guidance, a deepening of this system is expected Saturday night but associated with baroclinic process (interaction with the upper level trough, intrusion of dry air by the western and northern sectors). An hybrid or extratropical structure is likely by that time.

Sunday night or Monday, the system should sharply curved westwards on the northern side of the subtropical ridge. A weakening trend is anticipated by that time within an unfavorable environment (strong northerly shear, less baroclinic forcing).

Rodrigues Island is currently located about 110 km to the south west of an heavy rainfall area associated with the disorganized convective mass of this system. These precipitations do not get closer of the island at this time. On the forecast track, heavy rains should pass to the east and southeast of the island. However a small variation in track could bring this heavy rains over the island ... Consequently interest in Rodrigues island should continue to monitor the progress of weather conditions according to their national weather services.

Last advisory unless re-intensification about this system. It is closely monitored for sign of re-intensification.
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #17
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 2 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (990 hPa) located at 24.4S 40.0E has 10 minute sustained winds of 40 knots with gusts of 60 knots. The cyclone is reported as moving southwest at 15 knots.

Gale Force Winds
==========
20 NM radius from the center, extending up to 30 NM in the northeastern quadrant, up to 90 NM in the southeastern quadrant, and up to 140 NM in the southwestern quadrant

Near Gale Force Winds
=============
40 NM radius from the center extending up to 75 NM in the northeastern quadrant, up to 125 NM in the southeastern quadrant, and up to 250 NM in the southwestern quadrant

Dvorak Intensity: T3.0/3.5/S0.0/24 HRS

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

12 HRS: 24.9S 37.8E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 24.9S 35.6E - 50 knots (Forte Tempête Tropicale)
48 HRS: 25.2S 34.6E - 50 knots (Forte Tempête Tropicale)
72 HRS: 26.2S 34.1E - 60 knots (Forte Tempête Tropicale)

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

Convective activity strongly diminished along the day with now an exposed center on the northwestern edge of the cloud mass.

The system is suffering from a northerly to northwesterly shear constraint that appears weaker than this morning according to latest CIMSS analysis.

As expected, the track is gradually headed towards the west southwest with the rebuilding of the subtropical high pressures from the west. On Sunday, with a trough transiting in its south and a new barometric col situation, the system should temporarily track more southwards. This tendency is more pronounced now according to latest ECMWF deterministic and ensemble outputs.

Environmental conditions are not so good at this time : sea surface temperature favorable and established poleward outflow but persisting moderate northerly constraint. This constraint should abate tomorrow.

Tomorrow, intensification is expected and Irina could make a landfall or pass very close to the Mozambique coastline at a stronger intensity on Saturday afternoon or Saturday night, south of Inhambane.

On Sunday, it should move away from the coast and stay a bit longer than previously expected over seas. Irina could strengthen and make a come back towards the coast Tuesday as the subtropical ridge should rebuild to its south.

All interest along the Mozambican coasts between Maputo and Inhambane should closely monitor the progress of Irina.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #16
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
10:00 AM RET March 2 2012
=====================================

At 6:00 AM UTC, Moderate Tropical Storm Irina (987 hPa) located at 23.1S 41.0E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving west southwest at 15 knots.

Gale Force Winds
==========
20 NM radius from the center, extending up to 30 NM in the northeastern quadrant, up to 90 NM in the southeastern quadrant, and up to 140 NM in the southwestern quadrant

Near Gale Force Winds
=============
40 NM radius from the center extending up to 75 NM in the northeastern quadrant, up to 125 NM in the southeastern quadrant, and up to 250 NM in the southwestern quadrant

Dvorak Intensity: T3.0/3.5/S0.0/24 HRS

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

12 HRS: 24.3S 39.0E - 40 knots (Tempête Tropicale Modérée)
24 HRS: 24.6S 36.5E - 50 knots (Forte Tempête Tropicale)
48 HRS: 24.7S 34.2E - 40 knots (Depression sur Terre)
72 HRS: 25.5S 33.5E - 40 knots (Tempête Tropicale Modérée)

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

He system is suffering from a northerly to northwesterly shear constraint as seen in microwave imagery of last night and this morning. Latest ASCAT pass confirms current intensity and show a highly dissimetric wind structure.

As expected, the track is recurving progressively west southwestward with the rebuilding of the subtropical high pressures from the west. On Sunday, with a trough transiting in its south and a new barometric col situation, the system should temporarily track more southwards.

Environmental conditions are not so good : sea surface temperature favorable and established poleward outflow but persisting moderate northerly constraint. This constraint should abate tomorrow.

Irina will pass to the south of Europa later today but the island is not the "good" side with no major deterioration of weather conditions expected.

Beyond, intensification is expected and Irina could make a landfall or pass very close to the Mozambique coastline at the stage of tropical cyclone on Saturday afternoon or Saturday night, south of Inhambane.

On Sunday, it should temporarily come back over water in the bay of maputo and could make a new landfall Monday between Xai-Xai and Maputo.

All interest along the Mozambican coasts between Maputo and Inhambane should closely monitor the progress of Irina.


The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 12:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #15
FORTE TEMPETE TROPICALE IRINA (11-20112012)
4:00 AM RET March 2 2012
=====================================

At 0:00 AM UTC, Severe Tropical Storm Irina (981 hPa) located at 21.7S 42.3E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The cyclone is reported as moving southwest at 10 knots.

Storm Force Winds
=============
15 NM radius from the center

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

Near Gale Force Winds
=============
60 NM radius from the center extending up to 70 NM in the southern semi-circle

Dvorak Intensity: T3.5/3.5/D1.0/24 HRS

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

12 HRS: 23.3S 40.2E - 60 knots (Forte Tempête Tropicale)
24 HRS: 23.9S 37.8E - 70 knots (Cyclone Tropical)
48 HRS: 24.1S 34.4E - 45 knots (Tempête Tropicale Modérée)
72 HRS: 25.1S 32.4E - 30 knots (Depression sur Terre)

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

Cloud pattern has clearly improved within the past 6 hours and last infrared imagery displays convection wrapping 1 on log 10 spiral.

System is tracking southwestward towards a weakness in the mid-tropospheric subtropical high pressure.

Through 48 hours, the track is expected to recurve progressively west southwestward with the rebuilding of the subtropical high pressures from the west. On Sunday, with a trough transiting in its south, the system should temporarily track more southwestward.

Environmental conditions are good : sea surface temperature favorable, weak upper level wind shear under upper level high pressures and established poleward outflow through 36 hours.

Irina is also expected to keep on deepening. It should approach at 120 to 150 km south of Europa this morning, probably at the stage of severe tropical storm. Beyond, as it should keep on deepening, it should make a landfall at the stage of mature tropical cyclone on Saturday afternoon, on the Mozambique coastline, probably between Pomene and Maputo. On Sunday, it should temporarily come back over water in the bay of Maputo. Numerical weather prediction models are in good agreement for inland dissipation at the beginning of next week.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 6:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #9
PERTURBATION TROPICALE 12-20112012
4:00 AM RET March 2 2012
==============================

At 0:00 AM UTC, Tropical Disturbance 12 (1002 hPa) located at 15.2S 63.2E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving west southwest at 6 knots.

Dvorak Intensity: T2.0/2.0/S0.0/24 HRS

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

12 HRS: 15.9S 62.8E - 25 knots (Perturbation Tropicale)
24 HRS: 17.2S 63.1E - 30 knots (Depression Tropicale)
48 HRS: 20.2S 64.3E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 22.2S 62.1E - 35 knots (Depression Extratropicale)

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

Convection has rebuilt above the low level clockwise circulation since 01MAR/1500 PM UTC. The low level circulation is still very difficult to localize accuratly. ASCAT data at 01MAR/1704 PM UTC depicts a 15/20 kt clockwise low level circulation, reaching locally 25 knots in the southern semi-circle.

System tracks rather slowly west-south-westward north of the subtropical high pressure belt. Monsoon feeding is weak but a better poleward. System is still undergoing a east southeasterly moderate vertical wind shear, on the eastern edge of an upper level ridge.

The track should recurve towards the south southeast during through 48- 60 hours, under the steering influence of a near-equatorial ridge in the mid-troposphere in its northeast and of a weakness in the subtropical high pressure belt. On Sunday, with the rebuilding of the high pressure belt, it should recurve again westward.

Environmental conditions should not change significantly for the next 24 hours. On Saturday, monsoon inflow should improve and upper level wind shear should weaken slightly and system should strengthen a little. On and after Sunday, upper level wind shear should strengthen sharply ahead an upper level trough. However numerical weather prediction models deepen more significantly the system on and after Sunday. Baroclinic mechanisms should be responsible of this deepening. Consequently, system should begin its extratropical transition phase on and after Sunday.

Current intensity does not justify issuance of regular warnings
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #14
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
22:00 PM RET March 1 2012
=====================================

At 18:00 PM UTC, Moderate Tropical Storm Irina (985 hPa) located at 20.8S 43.3E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving south southwest at 12 knots.

Gale Force Winds
==========
30 NM radius from the center extending up to 50 NM in the southwestern quadrant and up to 60 NM in the northwestern quadrant

Near Gale Force Winds
=============
40 NM radius from the center, extending up to 80 NM in the western semi-circle

Dvorak Intensity: T3.5/3.5/D1.0/12 HRS

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

12 HRS: 22.9S 41.6E - 55 knots (Forte Tempête Tropicale)
24 HRS: 23.9S 39.2E - 70 knots (Cyclone Tropical)
48 HRS: 24.2S 35.4E - 80 knots (Cyclone Tropical)
72 HRS: 25.1S 33.0E - 40 knots (Depression sur Terre)

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

Deep convection has strengthen above the low level center since 1700 PM UTC. F17 microwave picture at 1522 PM UTC shows rather well organized convection structure.

System is keeping on south southwestward track and rapidly moves towards a barometric col. Within the next 24 hours, it is expected to recurve progressively southwestward and then west southwestward with the rebuilding of subtropical high pressures from the west. Overnight, energetic conditions improve oversea and environmental conditions remain good (no wind shear under upper level high pressures and growing of a poleward outflow).

Environmental conditions are also favorable for further intensification. System should track south of Europa Island tomorrow morning, at a distance of the order of 150 km, at the stage of severe tropical storm. System might be a mature tropical cyclone at its landfall on the Mozambique coastline expected Saturday evening, probably between Pomene and vicinity of Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Mauritius Meteorological Services
Tropical Cyclone Advisory #8
PERTURBATION TROPICALE 12-20112012
22:00 PM RET March 1 2012
==============================

At 18:00 PM UTC, Tropical Disturbance 12 (1000 hPa) located at 15.1S 63.7E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving west southwest at 6 knots.

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

Dvorak Intensity: T2.0/2.0/W0.5/24 HRS

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

12 HRS: 15.6S 62.8E - 25 knots (Perturbation Tropicale)
24 HRS: 16.3S 62.3E - 30 knots (Depression Tropicale)
48 HRS: 19.3S 65.1E - 35 knots (Tempête Tropicale Modérée)
72 HRS: 23.2S 63.5E - 35 knots (Depression Extratropicale)

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

Convection is very fluctuating above the low level clockwise circulation that is very difficult to localize. ASCAT data at 1704 PM UTC depicts a 15-20 kt clockwise low level circulation , reaching locally 25kt in the southern semi-circle.

System tracks rather slowly west southwestward north of the subtropical high pressure belt. Monsoon feeding is weak but a better poleward. System is still undergoing a east southeasterly moderate vertical wind shear, on the eastern edge of an upper level ridge.

System should keep on tracking west-south-westward during the next 24 hours. Beyond, it should recurve southeastward under the steering influence of a near-equatorial ridge in the mid-troposphere in its north-east and of a weakness in the subtropical high pressure belt. On Sunday, with the rebuilding of the high pressure belt, it should recurve again westward.

Environmental conditions should not change significantly for the next 24 hours. On Saturday, monsoon inflow should improve and upper level wind shear should weaken slightly and system should strengthen a little. On and after Sunday, upper level wind shear should strengthen sharply ahead an upper level trough. However numerical weather prediction models deepen more significantly the system on and after Sunday. Baroclinic mechanisms should be responsible of this deepening. Consequently, system should begin its extratropical transition phase on and after Sunday.

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 0:30 AM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581
Seychelles Meteorological Services
Tropical Cyclone Advisory #13
TEMPETE TROPICALE MODEREE IRINA (11-20112012)
16:00 PM RET March 1 2012
=====================================

At 12:00 PM UTC, Moderate Tropical Storm Irina (985 hPa) located at 19.8S 43.6E has 10 minute sustained winds of 45 knots with gusts of 65 knots. The cyclone is reported as moving south southwest at 12 knots.

Gale Force Winds
==========
40 NM radius from the center extending up to 50 NM in the southwestern quadrant and up to 80 NM in the northwestern quadrant

Near Gale Force Winds
=============
60 NM radius from the center extending up to 110 NM in the southwestern quadrant and up to 120 NM in the northwestern quadrant

Dvorak Intensity: T3.0/3.5/S0.0/12 HRS

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

12 HRS: 21.8S 42.1E - 50 knots (Forte Tempête Tropicale)
24 HRS: 23.3S 40.0E - 65 knots (Cyclone Tropical)
48 HRS: 24.2S 36.2E - 75 knots (Cyclone Tropical)
72 HRS: 24.8S 33.7E - 40 knots (Depression sur Terre)

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

System is rapidly moving southward and evolves again oversea. General pattern has not changed for the last hours, even if cloud tops are warmer.

Within the next 12 hours, system might keep on south southwestward track and rapidly move towards a barometric col. From Friday, it is expected that system progressively takes a west-southwestward track with rebuilding of subtropical high pressures from the west. Oversea, energetic conditions improve and environmental conditions remain good (no wind shear under upper level high pressures and establishment of a poleward outflow).

In agreement with last ECMWF run, chronology is faster in regard of previous forecast.

So, system might be a mature tropical cyclone during its landfall on the Mozambique coastline expected Saturday evening. As it is expected that system might make its landfall earlier and rather rapidly weaken inland, it does not undergo the influence of subtropical high pressures going far away eastward and mid-tropospheric trough coming from the west that should go again it oversea southward.

Potential threatened is situated on the coast between Pomene and vicinity of Maputo.

The next tropical cyclone advisory on TC Irina from Seychelles Meteorological Services will be issued at 18:30 PM UTC..
Member Since: May 24, 2006 Posts: 51 Comments: 45581

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