Category Archives: Fortnightly Weather Outlook

Subseasonal Weather Outlook (16 – 31 May 2020)

Issued 15 May 2020
Valid for weeks 3 and 4: 16 – 31 May 2020

For the second fortnight of May 2020, drier conditions are expected over western Mainland Southeast Asia (parts of Myanmar and Thailand), easing over Thailand and southern Myanmar in Week 4.

For most of the southern parts of Southeast Asia, there is an increased chance of wetter conditions, particularly in Week 3.

Warmer conditions are expected over most of Mainland Southeast Asia. Much of the Maritime Continent also has an increased chance of warmer conditions, except for parts of Peninsular Malaysia, Borneo and northern Philippines.

There was no clear Madden-Julian Oscillation (MJO) signal in the second week of May. While models predict an MJO to emerge over the Indian Ocean in Week 3, most models suggest the signal will be short-lived.

 
The outlook is assessed for the region in general, where conditions are relative to the average conditions for the corresponding time of year. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (1 – 15 May 2020)

Issued 29 April 2020
Valid for weeks 1 and 2: 1 – 15 May 2020

 
For the first fortnight of May 2020, drier conditions are expected to persist over most of northern Southeast Asia. However, for Myanmar, drier conditions are expected only in Week 2.

There is an increased chance of wetter conditions over the western Maritime Continent and southern parts of the eastern Maritime Continent associated with the Madden-Julian Oscillation (MJO) activity. The wetter conditions in the western Maritime Continent are expected to ease by Week 2.

For most of Southeast Asia, warmer conditions are expected throughout the first two weeks of May, with the warmest anomalies over parts of Cambodia, Laos and Viet Nam. Colder conditions are likely over northern and western Myanmar in Week 1.

An MJO is currently present over the eastern Indian Ocean. Some models predict the MJO to decay in Week 1 as it enters the Maritime Continent, while other models indicate the MJO may continue propagating through the region. If the MJO continues to propagate, this would increase the probability of wetter conditions in the eastern Maritime Continent.
 
The outlook is assessed for the region in general, where conditions are relative to the average conditions for the corresponding time of year. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (16 – 30 April 2020)

Issued 14 April 2020
Valid for weeks 3 and 4: 16 – 30 April 2020

For the second fortnight of April 2020, drier conditions are expected to persist over Thailand, Cambodia, southern parts of Laos, southern parts of Viet Nam, southern parts of Myanmar, and most parts of the Philippines. Drier conditions are also forecasted to persist over northern Borneo, although these conditions may ease in Week 4 tied to the Madden-Julian Oscillation (MJO) activity.

There is an increased chance of wetter conditions over western parts of the Maritime Continent in Week 4 (northern Sumatra, Peninsular Malaysia, and eastern Borneo), associated with the same MJO signal.

For temperature in Week 3, warmer conditions are expected over most of Southeast Asia, apart from northern Myanmar and northern Viet Nam. These warmer conditions are expected to persist in Week 4, although the warmer conditions may ease in the equatorial part of the region.

An MJO is currently present over Africa and is expected to propagate eastward through the Indian Ocean during Week 3 and Week 4. However, a few models forecast the signal to weaken towards the end of April.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (1 – 15 April 2020)

Issued 30 March 2020
Valid for weeks 1 and 2: 1 – 15 April 2020

 
For the first fortnight of April 2020, drier conditions are expected to persist over northern Sumatra, Peninsular Malaysia, southern parts of Mainland Southeast Asia, northern Borneo and most parts of the Philippines.

There is an increased chance of wetter conditions over some parts of the southeastern Maritime Continent in Week 1. For some parts of the southern Maritime Continent (Java), wetter conditions could redevelop in Week 2.

For temperature, warmer conditions are expected over most of Southeast Asia for the second fortnight of April 2020. Models predict a high chance of way-above average temperatures (exceeding 90%-tile) for some parts of Myanmar, especially in Week 1.

An Madden-Julian Oscillation (MJO) is currently present over the Indian Ocean and is expected to propagate eastward towards the Maritime Continent by Week 1. There is uncertainty across different models whether the MJO will continue to propagate to the western Pacific Ocean beyond Week 1.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (16 – 31 March 2020)

Issued 13 March 2020
Valid for weeks 3 and 4: 16 – 31 March 2020

For the second fortnight of March 2020, there is an increased chance of wetter conditions over some parts of the southern Maritime Continent in Week 3, easing in Week 4.

Drier conditions are expected to persist over northern Sumatra, Peninsular Malaysia, southern parts of Mainland Southeast Asia, northern Borneo and the Philippines throughout the fortnight.

For temperature, warmer conditions are expected over most parts of Mainland Southeast Asia for the second fortnight of March 2020. Warmer conditions are also expected over the southern-most parts of the Maritime Continent in Week 4.

A weak Madden-Julian Oscillation (MJO) is currently present in the eastern Maritime Continent. While most models predict the MJO to weaken at the start of the forecast period, there is a possibility of the MJO re-emerging over the Indian Ocean towards the end of Week 3.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (1 – 15 March 2020)

Issued 28 February 2020
Valid for weeks 1 and 2: 1 – 15 March 2020

For the first fortnight of March 2020, there is an increased chance of wetter conditions over northern Viet Nam and most parts of the southern Maritime Continent. These conditions are expected to ease gradually in Week 2. Drier conditions are expected over northern Sumatra, Peninsular Malaysia, southern parts of Thailand and the Philippines throughout the fortnight.

For temperature, warmer conditions are expected over most parts of Southeast Asia.

Some models predict a weak Madden-Julian Oscillation (MJO) emerging over the Maritime Continent in the first week of March. This development may contribute to the wetter conditions in the southern Maritime Continent predicted by the models.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (16- 29 February 2020)

Issued 14 February 2020
Valid for weeks 3 and 4: 16 – 29 February 2020

For the second fortnight of February 2020, there is an increased chance of wetter conditions over most of the southern Maritime Continent. These conditions are expected to ease gradually in Week 4.

Drier conditions are expected over northern Sumatra and western coastal Peninsular Malaysia. Drier conditions are also expected over northern parts of Borneo and southern parts of the Philippines.

For temperature, warmer conditions are expected over much of the Maritime Continent and parts of Mainland Southeast Asia in Week 4. Colder conditions may occur in Week 3 over northeastern parts of Mainland Southeast Asia.

There are signs of an Madden-Julian Oscillation (MJO) emerging in Maritime Continent in the second week of February. However most models predict this MJO to weaken during the start of the forecast period.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (1 – 15 February 2020)

Issued 31 January 2020
Valid for weeks 1 and 2: 1 – 15 February 2020

In the first fortnight of February 2020, drier conditions are expected over a broad region covering Sumatra, Peninsular Malaysia, northern parts of Borneo, and the Philippines. The drier conditions are expected to ease in the west in Week 2. There is an increased chance of wetter conditions over the southeastern part of the Maritime Continent. However, there is less confidence in the spatial extent and intensity of the wetter conditions.

For temperature, warmer conditions are expected over much of the Maritime Continent in the first fortnight. Colder conditions may occur in Week 1 over northeastern parts of the northern ASEAN region.

The Madden-Julian Oscillation (MJO) was in Phase 7 towards the end of January 2020 and has dissipated. There is no consistent signal in the dynamical models for an MJO to develop in the forecast period.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.

Subseasonal Weather Outlook (16 – 31 January 2020)

Issued 16 January 2020
Valid for weeks 3 and 4: 16 – 31 January 2020

In the second fortnight of January 2020, most areas in the ASEAN region, north of the Equator can expect drier-than-usual conditions, except for the western half of the Mekong sub-region where near average rainfall conditions may be expected. The drier conditions could partly be due to the propagation of the Madden-Julian Oscillation (MJO) during the fortnight from phase 6 to phases 7 – 8. These MJO phases typically bring drier conditions over the Southeast Asia region.

During the fortnight, most parts of the ASEAN region along and north of the Equator can expect warmer-than-usual conditions. For areas south of the Equator, warmer conditions may develop in Week 4 over southern Sumatra, Java and Lesser Sunda Islands.

The outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.