Category Archives: Fortnightly Weather Outlook

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.

Subseasonal Weather Outlook (16 – 31 December 2019)

Issued 16 December 2019
Valid for weeks 1 and 2: 16 – 31 December 2019

For the second half of December 2019, drier conditions are expected in some parts of the region, including northern Philippines, southern Viet Nam and southern Thailand. In Java, wetter conditions are expected in the last week of the month.

Most parts of the Mekong sub-region are expected to experience warmer conditions during the coming fortnight. Warmer conditions are also predicted for the areas surrounding the Java Sea, but are expected to ease in the second week of the fortnight.

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 December 2019)

Issued 3 December 2019
Valid for weeks 1 and 2: 1 – 15 December 2019

In the first fortnight of December 2019, wetter conditions are expected over the western Maritime Continent, including central Sumatra, Peninsular Malaysia, Singapore and parts of western Borneo.

In Week 1, wetter conditions are forecast for the Philippines as Typhoon Kammuri continues its track northwest during the period.

Over the other parts of the ASEAN region including most parts of the Mekong sub-region and the eastern Indonesian Archipelago, it is forecast to be dry.

With a surge of cool air from the northern Asian landmass expected to blow toward the Equatorial Southeast Asia region, the Mekong sub-region, South China Sea and the surrounding areas, including Peninsular Malaysia and parts of Sumatra can expect cooler temperatures during the outlook period. In contrast, warm conditions are forecast over the Indonesian Archipelago around the Java Sea region. These conditions are expected to ease slightly in Week 2.

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 – 30 November 2019)

Issued 15 November 2019
Valid for weeks 3 and 4: 16 November – 30 November

The positive Indian Ocean Dipole (IOD) is expected to persist into the second fortnight of November 2019 and contribute to the drier-than-average weather over areas south of the Equator. Drier-than-average conditions can also be expected in the southern parts of Thailand and Cambodia in the first week of the fortnight.

In contrast, wetter-than-average weather is expected over northern Philippines. The Madden-Julian Oscillation (MJO) is expected to continue to propagate eastwards from Phase 8, contributing to the wetter-than-average conditions over northern Sumatra and Peninsular Malaysia in Week 4.

Warmer-than-average conditions can be expected over many parts of the Mekong sub-region, and over areas around the Java Sea, including southern Sumatra and Kalimantan, and Java.

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.