Category Archives: Regional Weather Outlook for Year 2020

December 24, 2020

Subseasonal Weather Outlook (28 December 2020 – 10 January 2021)

Issued 24 December 2020
First forecast week: 28 December – 3 January
Second forecast week: 4 January – 10 January

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the next fortnight (28 December 2020 – 10 January 2021), an increased chance of wetter conditions is predicted over parts of northern ASEAN region, in particular the Philippines, northern Borneo, southern Viet Nam, Cambodia, southern Thailand and Peninsular Malaysia. A lower increase in likelihood of wetter conditions is also predicted around the southeastern part of the Maritime Continent in the second week (4 – 10 January 2021).

An increased chance of cooler conditions is predicted over most of Mainland Southeast Asia in the next fortnight (28 December 2020 – 10 January 2021).

The Madden-Julian Oscillation (MJO) signal is becoming indiscernible over the Western Pacific (Phase 6). Some dynamical models predict the MJO to re-emerge over the Indian Ocean in early January 2021, propagating eastwards towards the Maritime Continent in the second week.

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.

December 11, 2020

Subseasonal Weather Outlook (14 – 27 December 2020)

Issued 11 December 2020
First forecast week: 14 December – 20 December
Second forecast week: 21 December – 27 December

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the next fortnight (14 – 27 December), an increased chance of wetter conditions is predicted over the Philippines, parts of central and southern Viet Nam, southern Thailand and southern Myanmar. An increased chance of wetter conditions is also predicted around the southeastern part of the Maritime Continent in the first week (14 – 20 December). Drier conditions are predicted over parts of the equatorial region, in particular Borneo and central Sumatra for the next fortnight (14 – 27 December).

There is an increased chance of cooler conditions over southern parts of Indonesia in the first week (14 – 20 December), easing in the second week (21 – 27 December).

A weak Madden-Julian Oscillation (MJO) signal is present over the eastern Maritime Continent (Phase 5). Most models predict this MJO to continue propagating slowly eastwards over the Pacific, although weakening due in part to the La Niña conditions.

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.

November 27, 2020

Subseasonal Weather Outlook (30 November – 13 December 2020)

Issued 27 November 2020
First forecast week: 30 November – 6 December
Second forecast week: 7 December – 13 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

An increased chance of wetter conditions is predicted over parts of northern ASEAN region in the next fortnight (30 November – 13 December), in particular central and southern Viet Nam, southern Thailand and northern Philippines. A higher likelihood of wetter conditions is also predicted around the southeastern part of the Maritime Continent. Drier conditions are predicted over parts of the equatorial region in the first week (30 November – 6 December).

Cooler temperatures than usual are predicted over parts of eastern Mainland Southeast Asia in the next fortnight (30 November – 13 December), with a higher confidence in the first week (30 November – 6 December). An increased chance of warmer conditions is predicted over parts of central Sumatra and Borneo in the first week (30 November – 6 December).

Current MJO signal is weak. The dynamical models are inconsistent regarding the MJO development in the forecast period.

November 13, 2020

Subseasonal Weather Outlook (16 – 29 November 2020)

Issued 13 November 2020
First forecast week: 16 November – 22 November
Second forecast week: 23 November – 29 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over parts of Sumatra, Malay Peninsula and western Borneo in the first week (16 – 22 November).

Warmer conditions are predicted over much of Mainland Southeast Asia during the next two weeks (16 – 29 November). Warmer conditions are also predicted over parts of Java, southern Borneo and southern Sulawesi in the first week (16 – 22 November), with conditions easing by the second week (23 – 29 November).

An MJO signal is present over the Western Hemisphere and Africa (Phase 8). Most models predict the MJO to continue propagating eastwards, weakening over the Indian Ocean (Phases 2 and 3).

October 30, 2020

Subseasonal Weather Outlook (2 – 15 November 2020)

Issued 30 October 2020
First forecast week: 2 November – 8 November
Second forecast week: 9 November – 15 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Drier conditions are predicted over the western Maritime Continent and southern Mainland Southeast Asia next week (2 – 8 November), easing in the second week (9 – 15 November). Parts of this region may however, experience near-normal rainfall, particularly along eastern coasts of Sumatra and the Malay Peninsula.

Wetter conditions are predicted over northern Myanmar in the first week (2 – 8 November). Wetter conditions are also predicted over northern Philippines during this first week, possibly extending to the west in the second week (9 – 15 November), although the location and extent of these wetter conditions will depend on tropical cyclone development.

No significant regional temperatures anomalies are expected in Southeast Asia in the next fortnight (2 – 15 November).

A Madden-Julian Oscillation (MJO) signal is present over the Pacific (Phase 6). Most models predict the MJO to continue propagating eastwards, potentially strengthening over the Western Hemisphere and Africa (Phases 8 and 1) in the second week.

October 16, 2020

Subseasonal Weather Outlook (19 October – 1 November 2020)

Issued 16 October 2020
First forecast week: 19 October – 25 October
Second forecast week: 26 October – 1 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over eastern Mainland Southeast Asia and the Philippines for the next two weeks (19 October – 1 November), although the location and intensity of these wetter conditions will depend on tropical cyclone evolution. Wetter conditions are also predicted over parts of Java and southern Sumatra next week (19 – 25 October).

In general, drier conditions are predicted over the western Maritime Continent next week (19 – 25 October), gradually easing in the second week (26 October – 1 November). Parts of this region may however, experience near-normal conditions, particularly along eastern coasts of Sumatra and the Malay Peninsula.

Warmer temperatures are predicted over much of the equatorial region and northern Myanmar in the next fortnight (19 October – 1 November). Cooler temperatures than usual for this time of year are predicted over parts of Mainland Southeast Asia (Viet Nam, Lao PDR, northern Thailand and Cambodia).

A moderate Madden-Julian Oscillation (MJO) signal appears to be developing over the eastern Maritime Continent. Most models predict the MJO to propagate eastwards over the Pacific, although weakening slightly due in part to the La Niña conditions present.

October 2, 2020

Subseasonal Weather Outlook (5 – 18 October 2020)

Issued 2 October 2020
First forecast week: 5 – 11 October
Second forecast week: 12 – 18 October

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over the eastern half of Southeast Asia for the next two weeks (5 – 18 October). During this time, models are also predicting wetter conditions for eastern Mainland Southeast Asia (Cambodia, Lao PDR, Viet Nam, and parts of Thailand), although the location of these wetter conditions will depend on tropical cyclone evolution. Wetter conditions are also expected over northern Sumatra in week 1 (5 – 11 October).

Warmer temperatures are predicted for the central and northern parts of Myanmar for the next two weeks. Warmer temperatures are also predicted to develop over the western Maritime Continent in week 2 (12 – 18 October).

A weak Madden-Julian Oscillation (MJO) signal was present over the Maritime Continent at the beginning of October (Phase 5). However, none of the models predict a coherent MJO signal to develop in the next two weeks.

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.

September 21, 2020

Subseasonal Weather Outlook (21 September – 4 October 2020)

Issued 21 September 2020
First forecast week: 21 September – 27 September
Second forecast week: 28 September – 4 October

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over the equatorial region in the first week (21 – 27 September), easing in most places except Papua in the second week (28 September – 4 October).

Warmer conditions are expected during the fortnight over most of Mainland Southeast Asia (except northern Myanmar), the Philippines and southern parts of Southeast Asia, with closer to normal temperatures in the equatorial region (corresponding to the wetter conditions in the rainfall outlook).

The previous Madden-Julian Oscillation (MJO) signal weakened after entering the Maritime Continent (Phase 4), just before the start of the forecast period. Most models predict this weak MJO signal to continue propagating across the Maritime Continent and over the Western Pacific.

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.

September 7, 2020

Subseasonal Weather Outlook (7 – 20 September 2020)

Issued 7 September 2020
First forecast week: 7 September – 13 September
Second forecast week: 14 September – 20 September

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the northern part of Southeast Asia, drier conditions are predicted to persist for the first week (7 – 13 September), before returning to normal in the second week (14 – 20 September). For the equatorial region, wetter conditions are predicted in the first week, gradually easing in most places the following week, except for southern Thailand, northern Borneo and northern Sulawesi.

Warmer conditions are expected during the fortnight over northern and southern parts of Southeast Asia, with closer to normal temperatures in the equatorial region (corresponding to the wetter conditions in the rainfall outlook).

At the start of September, a Madden-Julian Oscillation (MJO) signal was present in the Indian Ocean (Phase 3). Most models predict this MJO to decay by the start of the first week of the forecast.

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.

August 21, 2020

Subseasonal Weather Outlook (24 August – 6 September 2020)

Issued 21 August 2020
First forecast week: 24 August – 30 August
Second forecast week: 31 August – 6 September

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the first week (24 – 30 August), wetter conditions are predicted around the equatorial region. The wetter conditions are expected to spread further southwards in the second week (31 August – 6 September). For the northern part of Southeast Asia, drier conditions are predicted for the fortnight, with higher likelihood in the first week.

Warmer conditions are expected during the fortnight over most parts of Southeast Asia except for the western Maritime Continent (parts of Peninsular Malaysia, Sumatra, and Borneo), corresponding to the rainfall outlook.

A Madden-Julian Oscillation (MJO) signal recently emerged in Western Hemisphere (Phase 8). Models predict the MJO to propagate eastwards towards Africa and the Indian Ocean during the fortnight.