Low-pressure circulation east-southeast of Diego-Garcia :

At present, the 0422UTC ASCAT swath locates a closed circulation towards 9°S/78.8°E (whose

low-level vortex is visible on the satellite animations) with maximum winds of around 20kt. The

associated convective activity is located in the western part of the circulation, due to strong shear in

this area. Although the shear is much less pronounced to the south, the circulation should not be

able to reach this more favorable environment, and is therefore unlikely to persist or intensify over

the next few days.

Suspect area north of the Mascarene Islands:

Recent ASCAT swath still do not allow us to define a circulation in this area, with the exception of a

large low-pressure zone around 7°S between 58°E and 66°E. With continued convective activity

over this zone, vorticity should take hold over the next 2-3 days, defining a real potential for

cyclogenesis north of the Mascarene Islands. Deterministic and probabilistic models are in

agreement in proposing the formation of a low-pressure minimum over the northern Mascarene

Islands by Thursday to Friday, gradually intensifying. With favorable environmental conditions

(low shear, moisture in the monsoon trough, sufficient low-level convergence), this minimum could

deepen rapidly and reach the stage of a moderate tropical storm over the coming weekend. The

timing of this deepening remains to be determined, as there are currently discrepancies between

models, but the risk of moderate tropical storm formation is now moderate for Saturday and high

for Sunday. The new forecasts confirm the trend for a track towards the Mascarene Islands,

although the tendency is for the storm to move further and further to the east of Réunion Island.

The risk of a moderate tropical storm is low on Friday, becoming high from Sunday over the

northern Mascarene Islands.

Forecast description

Tropical Low 03U

Potential tropical cyclone west of Darwin this weekend.

A monsoon trough develops across the Top End and adjacent waters later this week.

A tropical low (03U) is likely to develop within this trough near the Joseph Bonaparte Gulf, west of Darwin.

The tropical low is likely to be slow moving but with high uncertainty on its direction in the longer term, possibly moving east and over the NT or moving southwest and near the WA coast.

If the low remains over water conditions are favourable for development into a tropical cyclone.

Regardless of the development of 03U, the monsoon is expected to bring an increase in rainfall to parts of northern Australia.

Last updated

6 hours ago, 07:38 pm AEST

Tropical Low 04U

Potential tropical low early next week in the Indian Ocean.

A tropical low (04U) may develop in the Indian Ocean from this weekend.

At this stage it is not expected to develop into a tropical cyclone although the chance increases slightly next week.

The low is expected to be slow moving. It may move west of the Australian region next week.

Should it move close to Cocos Islands it may lead to an increase in showers or storm activity.

Last updated

6 hours ago, 07:36 pm AEST

Tropical Low 05U

Monsoon in the Gulf of Carpentaria may lead to cyclone development

A tropical low could develop within the monsoon trough over the Gulf of Carpentaria this weekend

Potential for it to develop into a tropical cyclone increases marginally on the weekend

If 03U moves further east then it is less likely that 05U will develop.

Last updated

6 hours ago, 07:47 pm AEST

Weak low level clockwise circulation east of Diego-Garcia:

A weak low is observed on imagery around 7.5°S / 78.8°E. Its low level center is set back to the

east of the main convection. This is due to strong easterly upper windshear, which is unlikely to

weaken over the next few days. What's more, low-level convergence will struggle to feed warm air

into the center of this vortex.

As a result, this minimum is unlikely to persist or even intensify over the next 5 days.

Suspect area north of the Mascarene Islands:

Analysis of CIMSS products (low level vorticity + MIMIC TPW) and animation of the latest visible

images show the beginnings of a weak surface low-pressure circulation north of the Mascarene

Islands, towards 11°S / 64°E. The partial pass of HY-2C from 0530Z (on the edge of the swath)

does not yet show a closed circulation, but a fairly elongated structure marked by mean surface

winds of around 10 to 15kt maximum, with a fairly cold band of clouds, far from the center in the

eastern semicircle.

In the short term, with convective activity continuing over this area, the precursor should gradually

symmetrize and begin its intensification phase, over particularly warm surface waters and a

particularly moist middle troposphere. From Friday onwards, low-level convergence should

improve, particularly over the eastern semicircle of the vortex. In addition, there will be a strong

upper-level divergence, with an evacuation channel developed on the polar side. Under these

conditions, the system should end its initial cyclogenesis phase and begin a process of

intensification, defining a more or less direct threat to inhabited land.

For the time being, however, major differences persist between the main deterministic models, not

only in terms of timing but also in terms of movement. The French model Arome suggests a

transition to a moderate tropical storm (TTM) on Friday evening, or even overnight. The American

GFS model suggests a TTM stage on Saturday morning, with the meteor circulating to the east of

Mauritius, while the European IFS model takes longer to set up, but digs in as a severe tropical

storm to the north of the Mascarene Islands on Sunday morning, passing as close as possible

between Mauritius and La Réunion late Monday.

The ensemblist guidance systems are fairly close to their respective determinists, with a more

parabolic track for EPS, and a meridian one for GEFS.

As a result of these latest elements, which are still subject to uncertainties, the risk of a

moderate tropical storm forming is considered to be low on Thursday, moderate on Friday

and then high from Saturday, over the northern Mascarene Islands.

Forecast description

Tropical Low 03U

Potential for tropical cyclone in the southern Joseph Bonaparte Gulf on the weekend.

A monsoon trough is developing across the Top End and adjacent waters with increased rain areas and thunderstorm activity.

A tropical low (03U) may form along the trough, near southern Joseph Bonaparte Gulf, southwest of Darwin on Thursday or Friday.

03U could be slow moving over the weekend, remaining over water and possibly strengthening into a tropical cyclone. There is a low possibility that it may continue moving south or south-eastwards as well, in which case it could be located over land.

By Monday, 03U is likely to be over land in the Northern Territory or the Kimberley in Western Australia. The system is unlikely to remain as a tropical cyclone but could bring widespread heavy rainfall.

There is uncertainty regarding 03U's movement beyond Monday. The most likely scenario is that it may remain over inland NT or northern WA until late Wednesday 17 January.

Last updated

5 hours ago, 07:32 pm AEST

Tropical Low 04U

Potential tropical low early next week north of Cocos Islands.

A tropical low (04U) may form North of Cocos Islands from early next week.

There is a small chance of it reaching tropical cyclone strength from late Monday next week, particularly if the system moves further south

The low is expected to be slow moving. It may move west of the Australian region next week.

If it moves close to Cocos Islands it may lead to an increase in showers or storm activity.

Last updated

5 hours ago, 07:23 pm AEST

Tropical Low 05U

Monsoon trough in the Gulf of Carpentaria could lead to the formation of a tropical low

There is a chance Tropical Low 05U forms in the monsoon trough over the Gulf of Carpentaria from as early as Friday.

From Sunday there is a Low chance of 05U strengthening into a tropical cyclone. It would need to remain over water for this to occur.

Over the weekend and next week, it could move east or south taking it over land or across Cape York Peninsula and into the Coral Sea.

If Tropical Low 03U moves east, then it is less likely 05U will form or strengthen.

Last updated

5 hours ago, 07:23 pm AEST

Zone of Disturbed Weather 02-20232024 : 

Information at 0930UTC

Location : 10.1S / 60.1E

Motion : S 6kt

Max average winds (10min) : 20kt

MSLP : 1006 hPa

For further information, please refer to warnings WTIO20 and WTIO30 to be issued at 12Z. 

Clockwise circulation east of Diego-Garcia :

The weak circulation monitored over the last few days continues to lose definition. A residual 

vortex is still visible on satellite images. According to the latest observations, winds are reaching 

20kt in the northern semicircle. It should disappear definitively within the next 24 hours.

East of 90E : 

A broad cyclonic circulation is currently present in the Indonesian area. It is currently being 

monitored by the BOM, which predicts a low risk (10-15%) of it developing into a tropical storm 

east of 90E. For the short range, the environment seems unfavorable to its development (weak 

surface convergence, shear). However, these conditions could improve early next week, leading to a

phase of intensification near our area of responsibility. For the time being, only GFS and a few 

members of ensemble forecasters are suggesting that a storm will arrive in our basin only after next 

Wednesday.

Currently, there is no risk of a moderate tropical storm entering our area of responsability 

from the east, for the next five days (up to Tuesday 16)

Near the north of Madagascar : 

Early next week, the Monsoon flow surge could favor the formation of a low north of the 

Mozambique Channel. This minimum could move eastwards, crossing northern Madagascar before 

moving over the Indian Ocean. Initially, the environment seems to be unfavorable for significant 

development, due to the lack of convergence on the southern side in the channel and the presence of

Madagascar landmass. From mid-week onwards, conditions could be more favorable east of 

Madagascar.

Currently, there is no risk of for the development of a moderate tropical storm next to the 

north of Madagascar for the next five days (up to Tuesday 16).

Forecast description

Tropical Low 03U

Tropical low in the Joseph Bonaparte Gulf a Low chance of developing into a tropical cyclone.

An active monsoon trough lies across the Joseph Bonaparte Gulf and the Top End with increased rain areas and thunderstorm activity.

A tropical low (03U) is developing in the trough over the southern Joseph Bonaparte Gulf.

Once formed, 03U is expected to slowly move southwards during the weekend. There is a low chance that it may have sufficient time over southern Joseph Bonaparte Gulf waters to develop into a tropical cyclone by Sunday, before it moves over land by Monday.

From Monday onwards and into next week, there is increasing confidence that 03U is likely to remain over inland Northern Territory.

Although 03U is unlikely to develop into a tropical cyclone, it is likely to bring widespread rainfall and thunderstorms and possibly monsoonal gales over the Top End and Kimberley region.

Last updated

6 hours ago, 07:36 pm AEST

Tropical Low 05U

Tropical low may form in the Gulf of Carpentaria and move into the Coral Sea early next week.

Tropical low 05U may form along the monsoon trough over the southern Gulf of Carpentaria from as early as Friday.

05U may remain slow moving in the Gulf of Carpentaria until early next week, when it may move to the east, across the Cape York Peninsula and into the northern Coral Sea.

If it forms, there is a low risk of 05U developing into a tropical cyclone in the Gulf of Carpentaria from Sunday onward, or in the Coral Sea early to mid-next week.

Last updated

6 hours ago, 07:52 pm AEST

Tropical Depression 02-20232024 :

Information at 10UTC

Location : 13.2S / 56.7E

Motion : SW 9kt

Max average winds (10min) : 30kt

Estimated central pressure : 1000 hPa

For more information, please refer to warnings WTIO22 and WTIO30 issued at 12Z and following.

East of 90E :

A broad cyclonic circulation is currently present in the Indonesian area. It is currently being

monitored by the BOM, which forecasts a moderate risk (25%) of it developing into a tropical

storm east of 90E. In the short term, the environment seems quite unfavorable for development

(weak surface convergence, wind shear). However, these conditions could improve early next week,

leading to a phase of intensification near our area of responsibility. Only GFS and a few members of

the ensemble forecasts suggest that a storm will arrive in our basin from next Wednesday.

There is a very low risk of a new tropical storm entering from the east of the basin from

Wednesday 17th.

Near northwestern Madagascar :

Early next week, a monsoon flow surge could favor the formation of a small low over the northern

Mozambique Channel, which could move near the Malagasy coast off Majunga or Cape Saint

André. However, the environment seems rather unfavorable for significant development, due to lack

of convergence on the southern side of the channel and due to Malagasy landmass proximity.

Nevertheless, some ensemble scenarios continue to suggest a low probability of development from

Wednesday onwards as conditions become a little more favorable.

There is a very low risk of another tropical storm forming near northwestern Madagascar

from Wednesday 17th.

Forecast description

Tropical Low 03U

Monsoon over the Top End.

The monsoon trough is over the Top End and adjacent waters producing widespread rain and thunderstorms.

A tropical low is expected to develop in the trough over the western Top End and be slow moving.

There is a small possibility that it moves over the Joseph Bonaparte Gulf where it could develop into a tropical cyclone.

Last updated

5 hours ago, 10:29 am AEST

Tropical Low 05U

Monsoon extending over Cape York Peninsula.

A tropical low may develop this weekend within the monsoon trough over the eastern Gulf of Carpentaria.

It is likely to remain weak and slowly move east across the Cape York Peninsula during the weekend and then continue through the Coral Sea and away from the Queensland coast next week.

It is not expected to strengthen into a tropical cyclone.

Last updated

5 hours ago, 10:55 am AEST

Forecast description

Tropical Low 05U

Monsoon extending over Cape York Peninsula and into Coral Sea.

A tropical low is expected to develop within the monsoon trough in the Coral Sea early in the week.

It is likely to remain weak as it moves east through the Coral Sea and away from the Queensland coast.

Later in the week it could begin to strengthen while well offshore of the Queensland coast.

Last updated

36 minutes ago, 07:42 pm AEST