Category Archives: Regional Weather Outlook for Year 2019

Subseasonal Weather Outlook (1 – 15 July 2019)

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

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the first fortnight of July 2019, drier-than-average conditions are expected over parts of the southern ASEAN region, including the southern parts of Sumatra and Kalimantan, and Java. Wetter-than-average conditions may develop over parts of eastern Maritime Continent and eastern Mekong sub-region in Week 1.

Warmer-than-average conditions present over the inland parts of the northern ASEAN region are expected to ease.

There is currently no significant Madden-Julian Oscillation (MJO) signal present. For the first fortnight of July 2019, there are no consistent signs of an MJO re-developing.

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 June 2019)

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

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the first half of June 2019, drier than average conditions are expected to persist over Myanmar.

For the rest of the northern ASEAN region, the prevailing drier than average conditions are likely to ease.

During the forecast period, the MJO that is currently active in the western hemisphere and Africa is forecast to propagate eastwards over the Indian Ocean. The presence of the MJO in Week 1 may bring wetter than average conditions over parts of the equatorial ASEAN region, including Sumatra, southern Peninsular Malaysia and south-western Borneo. However, drier than average conditions conditions can be expected over the areas surrounding Java Sea and Banda Sea.

Warm conditions are expected to continue over most of the northern 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 (16 May – 31 May 2019)

Issued 15 May 2019
Valid for weeks 3 and 4: 16 May – 31 May

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For the second half of May, drier-than-usual conditions are expected to persist in Myanmar, the southern Philippines, as well as northern and central Thailand. By the second week of the fortnight, the drier conditions are expected to extend over most parts of the northern ASEAN region.

In the southern ASEAN region, wetter-than-usual conditions are expected to develop over parts of Peninsular Malaysia, Sumatra and West Kalimantan towards the middle of the fortnight, and subsequently ease in the last week of May. The wetter conditions are associated with the Madden-Julian Oscillation (MJO), which is predicted to propagate eastwards through Phase 7 and Phase 8, and into Phase 1.

Most parts of the northern ASEAN region are expected to experience warmer-than-average conditions in the coming 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 May – 15 May 2019)

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

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

May lies within the inter-monsoon period where prevailing winds over the Southeast Asia region are typically light and variable in direction. During this period, the monsoon rain band lies over the equatorial region and usually brings rainy weather over most parts of the Southeast Asia region.

In the coming fortnight, drier-than-usual conditions are expected to persist over parts of the Mekong sub-region, particularly over Myanmar. Meanwhile, wetter-than-usual conditions are forecast over the southwestern Maritime Continent, including the Java region. This is associated with the passage of Madden-Julian Oscillation (MJO) through the western Maritime Continent in Week 1. In the eastern Maritime Continent, drier-than-usual conditions are forecast to develop north of the equator in Week 1, spreading to the south of the equator in Week 2.

Warm conditions are expected to persist over most of the northern ASEAN region, as well as Peninsular Malaysia and Singapore.

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 Apr – 30 Apr 2019)

Issued 12 Apr 2019
Valid for weeks 3 and 4: 16 Apr – 30 Apr

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the third week of April 2019, drier-than-usual conditions are expected to develop over parts of the Mekong sub-region, as well as over Malaysia and the Philippines. In the last week of the month, wetter-than-usual conditions are expected to develop over parts of Indonesia, with a possible development of Madden-Julian Oscillation (MJO) over the Indian Ocean. Most models predict the MJO to propagate slowly towards the east into the western Maritime Continent before weakening.

Warm conditions are expected to persist over the Mekong sub-region, as well as the northern part of Peninsular Malaysia.

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 Apr – 15 Apr 2019)

Issued 31 Mar 2019
Valid for weeks 1 and 2: 1 Apr – 15 Apr

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

During this time of year, the Northeast Monsoon season typically weakens and transitions to the inter-monsoon period, during which more shower activities over the ASEAN region can be expected.

In the second week of April 2019, drier conditions are forecast to redevelop over many areas north of the Equator, except northern Viet Nam and parts of Lao PDR, Myanmar, and Cambodia. There are no other significant regional rainfall anomalies expected during the first fortnight.

Warmer temperatures are expected over Peninsular Malaysia and most parts of the Mekong sub-region except for Myanmar, particularly in the second week.

There is currently no significant signal shown by the Madden-Julian Oscillation (MJO), and most model predictions indicated no significant MJO activity would develop in the first half of April 2019.

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 Mar – 31 Mar 2019)

Issued 15 Mar 2019
valid for weeks 3 and 4: 16 Mar – 31 Mar

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the coming fortnight, drier-than-average conditions are expected to continue over the Philippines and the equatorial region around the South China Sea.

Wetter-than-average conditions are expected to continue over the southern Maritime Continent during Week 3 but an easing of conditions are expected in in Week 4.

The Madden-Julian Oscillation (MJO) that has been active in Phase 4 since the second week of March 2019 is weakening and is expected to weaken further in the coming fortnight. This could bring wet weather to the southern parts of the Maritime Continent, in particular over the Java and Banda Sea areas in Week 3.

The prevailing dry and warm conditions over the Southeast Asia region can be attributed to the mass of dry air from a high pressure system in the Pacific Ocean that has extended over the Southeast Asia region. The dry mass of air is forecast to persist in Week 3, and is expected to bring warmer-than-average temperatures over most parts of the Mekong sub-region, Peninsular Malaysia and northern Sumatra.

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.