Category Archives: Regional Weather Outlook for Year 2019

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.

Subseasonal Weather Outlook (1 – 15 November 2019)

Issued 31 October 2019
Valid for weeks 1 and 2: 1 November – 15 November

Drier-than-average conditions are forecast over many areas in the southern ASEAN region with the positive phase of the Indian Ocean Dipole (IOD) persisting. However, wetter conditions are expected over northern Sumatra and Peninsular Malaysia in the first week of the fortnight due to the development of the Madden-Julian Oscillation (MJO) .

Wetter-than-average conditions can be expected over the Philippines and coastal Viet Nam in the first fortnight of November, although the rainfall in Viet Nam is expected to return to near-average conditions during the second week.

Warmer-than-average conditions are expected over the western half of the Mekong sub-region and around the Java Sea area.

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 October 2019)

Issued 30 September 2019
Valid for weeks 1 and 2: 1 October – 15 October

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Drier conditions can be expected over most parts of the ASEAN region in the first fortnight of October 2019. However, wetter conditions are forecast over the equatorial ASEAN region, including northern Sumatra, Peninsular Malaysia, Sarawak, and Kalimantan in the first week under the influence of the Madden – Julian Oscillation (MJO), which is currently in Phase 1. The MJO is forecast to weaken during the first week.

Warmer-than-average conditions are also expected to prevail over much of the Mekong sub-region.

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 September 2019)

Issued 2 September 2019
Valid for weeks 1 and 2: 1 September – 15 September

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

With the Indian Ocean Dipole (IOD) expected to remain in the positive phase, drier-than-usual conditions are forecast to persist over many parts of the southern ASEAN region, including Sumatra, Kalimantan and the Java Sea areas.

For the northern ASEAN region, above-average rainfall is forecast over the central and southern parts of the Mekong sub-region, as well as over the Philippines in Week 1.

During the first fortnight of September 2019, warmer conditions are expected over much of equatorial region.

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 August 2019)

Issued 18 August 2019
Valid for weeks 3 and 4: 16 August – 31 August

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the northern ASEAN region, the third week of August 2019 is expected to be drier-than-usual except for the northern parts of the Mekong sub-region. In the last week of the month, near-average rainfall is expected for the region. In the southern ASEAN region, drier-than-usual conditions are forecast over Singapore, southern Peninsular Malaysia and many areas in Indonesia during the fortnight. The drier conditions in the southern ASEAN region can be partly attributed to the influence of the Indian Ocean Dipole (IOD) in the positive phase.

During the second fortnight of August 2019, warmer conditions are expected over many parts of the ASEAN region.

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 August 2019)

Issued 1 August 2019
Valid for weeks 1 and 2: 1 August – 15 August

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the first fortnight of August 2019, above-average rainfall is predicted over northern Philippines, Viet Nam, parts of Myanmar and southern Thailand. With the Indian Ocean Dipole (IOD) predicted to remain in its positive phase, the southern ASEAN region and southern parts of the Philippines may experience drier-than-usual conditions.

In terms of temperature, warmer-than-average conditions can be expected over the equatorial ASEAN region and the inland areas of Thailand.

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 July 2019)

Issued 12 July 2019
Valid for weeks 3 and 4: 16 July – 31 July

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the second fortnight of July 2019, wetter-than-average conditions can be expected over southern half of the northern ASEAN region, including the northern half of the Philippines. In the first week of this fortnight, warmer-than-average conditions are predicted over Myanmar and Thailand as well as over Lao PDR. Drier-than-average conditions are expected over the southern ASEAN region except for northern Sumatra and Peninsula Malaysia where average rainfall are predicted.

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.