Category Archives: Fortnightly Weather Outlook

CR58

February 3, 2023

Subseasonal Weather Outlook (6 – 19 February 2023)

Issued: 3 February 2023
First forecast week: 6 February 2023 – 12 February 2023
Second forecast week: 13 February 2023 – 19 February 2023

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Drier conditions are expected over parts of the western and central Maritime Continent in Week 1 (6 – 12 February). These drier conditions are predicted to persist over the central Maritime Continent in Week 2 (13 – 19 February) and likely easing over the western Maritime Continent.

Wetter conditions are predicted over the northeastern Maritime Continent and southeastern coast of Mainland Southeast Asia in Week 2 (13 – 19 February).

Warmer than usual temperature is expected over much of the eastern half of Mainland Southeast Asia and much of the Philippines in Week 1 (6 – 12 February). Warmer than usual temperature is also expected over parts of the western and central Maritime Continent in Week 1, in line with the predicted drier conditions.

A Madden-Julian Oscillation (MJO) signal was present over the Indian Ocean (Phase 3) at the start of February. Models predict the MJO signal to propagate eastwards and reach the Maritime Continent (Phases 4 and 5) during the first week of the forecast period. Some models then predict this signal to continue propagating through the Maritime Continent to the Western Pacific (Phases 6 and 7), while others predict the signal to decay over the 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.

January 20, 2023

Subseasonal Weather Outlook (23 January – 5 February 2023)

Issued: 20 January 2023
First forecast week: 23 January 2023 – 29 January 2023
Second forecast week: 30 January 2023 – 5 February 2023

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over much of the Maritime Continent and coastal parts of eastern Mainland Southeast Asia in the next fortnight (23 January – 5 February). The highest likelihood of wetter conditions is over the region between 0° and 10°N, including the Malay Peninsula, northern Borneo, and the southern Philippines, in Week 1 (23 – 29 January).

Cooler than usual temperature is predicted over much of the southern half of the ASEAN region in Week 1 (23 – 29 January), generally in line with the predicted wetter conditions.

No clear Madden-Julian Oscillation (MJO) signal was present during the third week of January. Some models predict an MJO signal to develop and propagate eastward over the Indian Ocean (Phases 2 and 3) during the forecast period.

January 6, 2023

Subseasonal Weather Outlook (9 – 22 January 2023)

Issued: 6 January 2023
First forecast week: 9 January 2023 – 15 January 2023
Second forecast week: 16 January 2023 – 22 January 2023

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over much of southeastern Mainland Southeast Asia and the Philippines in the next fortnight (9 – 22 January). Wetter conditions are also predicted to develop over the western Maritime Continent in Week 2 (16 – 22 January).

Drier conditions are predicted over parts of the southern Maritime Continent in Week 1 (9 – 15 January).

Warmer than usual temperature is predicted around central and northeastern Mainland Southeast Asia in Week 1 (9 – 15 January).

A Madden-Julian Oscillation (MJO) signal weakened over the Western Pacific (Phase 7) at the start of January. Most models predict this MJO signal to strengthen again as the signal propagates eastward over the Western Hemisphere and Africa (Phases 8 and 1) during Week 1, and reaching the Indian Ocean (Phases 2 and 3) during Week 2.

December 23, 2022

Subseasonal Weather Outlook (26 December 2022 – 8 January 2023)

Issued: 23 December 2022
First forecast week: 26 December 2022 – 1 January 2023
Second forecast week: 2 January 2023 – 8 January 2023

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are expected over the southern Maritime Continent in Week 1 (26 December 2022 – 1 January 2023). Wetter conditions are also predicted over parts of the northeastern Maritime Continent in the next fortnight (26 December 2022 – 8 January 2023), extending to southeastern Mainland Southeast Asia in Week 2 (2 – 8 January 2023). Drier conditions are predicted over the western Maritime Continent and the equatorial region in Week 1.

Cooler than usual temperature is predicted over much of central and eastern Mainland Southeast Asia in the next fortnight (26 December 2022 – 8 January 2023). Cooler conditions are also expected over much of the western and southern Maritime Continent in the next fortnight. Warmer than usual temperature is predicted over parts of the eastern equatorial region in Week 1 (26 December 2022 – 1 January 2023).

In the third week of December, a weak Madden-Julian Oscillation (MJO) signal was present over the Maritime Continent (Phases 4 and 5) based on the RMM index. Most models predict this MJO signal to propagate eastwards to the Western Pacific (Phase 6) in Week 1. There is a disagreement between the models for the MJO signal to either decay or continue propagating eastwards in Week 2.

December 9, 2022

Subseasonal Weather Outlook (12 – 25 December 2022)

Issued: 9 December 2022
First forecast week: 12 December – 18 December
Second forecast week: 19 December – 25 December

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over parts of the western Maritime Continent in the next fortnight (12 – 25 December). Wetter conditions are also predicted over the northeastern Maritime Continent in Week 2 (19 – 25 December).

Cooler than usual temperature is expected in Week 1 (12 – 18 December) over much of central and eastern Mainland Southeast Asia and the western Maritime Continent. In Week 2 (19 – 25 December), these cooler conditions are predicted to ease over eastern Mainland Southeast Asia and persist elsewhere. Warmer than usual temperature is predicted over much of Myanmar in the next fortnight (12 – 25 December).

No discernible Madden-Julian Oscillation (MJO) signal was present in the first week of December based on the RMM index. There is disagreement between the models regarding MJO development, although most models predict any MJO signal to be weak and stay within the unit circle in the RMM diagram during the forecast period.

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 25, 2022

Subseasonal Weather Outlook (28 November – 11 December 2022)

Issued: 25 November 2022
First forecast week: 28 November – 4 December
Second forecast week: 5 December – 11 December

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over much of eastern and southern Mainland Southeast Asia, and the Philippines in the next fortnight (28 November – 11 December). Wetter conditions are also predicted over the southeastern Maritime Continent in Week 1 (28 November – 4 December).

For temperature, warmer than usual temperature is expected over much of Myanmar in the next fortnight (28 November – 11 December).

During the third week of November, a Madden-Julian Oscillation (MJO) signal propagated to the Western Pacific (Phase 6). Most models forecast the MJO signal to continue propagating eastwards over the Western Pacific (Phase 7) and to dissipate during Week 1.

November 11, 2022

Subseasonal Weather Outlook (14 – 27 November 2022)

Issued: 11 November 2022
First forecast week: 14 November – 20 November
Second forecast week: 21 November – 27 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are predicted over much of the southern and eastern Maritime Continent in the next fortnight (14 – 27 November). Wetter conditions are also predicted over the southern half of Mainland Southeast Asia in Week 1 (14 – 20 November), easing in Week 2 (21 – 27 November).

Drier conditions are predicted in Week 2 (21 – 27 November) over the western Maritime Continent and some parts of the central Maritime Continent.

Warmer than usual temperatures are expected over northeastern Mainland Southeast Asia in the next fortnight (14 – 27 November).

In mid-November, no discernible Madden-Julian Oscillation (MJO) signal was present based on the RMM index. While some models predict an MJO activity over the eastern Maritime Continent and the Western Pacific (Phases 5 and 6) during the forecast period, others predict no significant MJO activity.

October 28, 2022

Subseasonal Weather Outlook (31 October – 13 November 2022)

Issued: 28 October 2022
First forecast week: 31 October – 6 November
Second forecast week: 7 November – 13 November

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

Wetter conditions are expected over parts of the eastern Maritime Continent in the next fortnight (31 October – 13 November). Wetter conditions are also predicted over parts of the southwestern Maritime Continent in Week 2 (7 – 13 November).

Drier conditions are expected over much of central and eastern Mainland Southeast Asia in Week 1 (31 October – 6 November).

Cooler than usual temperature is expected over much of central and southeastern Mainland Southeast Asia in Week 1 (31 October – 6 November).

A Madden-Julian Oscillation (MJO) signal was present over the Western Pacific (Phases 6 and 7) towards the end of October based on the RMM Index. Most models forecast MJO activity to be predominantly over the Western Pacific in the forecast period.

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.

October 14, 2022

Subseasonal Weather Outlook (17 – 30 October 2022)

Issued: 14 October 2022
First forecast week: 17 October – 23 October
Second forecast week: 24 October – 30 October

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For rainfall, wetter conditions are expected over much of the central Maritime Continent in the next fortnight (17 – 30 October). Wetter conditions are also predicted around the Malay Peninsula in Week 1 (17 – 23 October). Drier conditions are expected over much of western and central Mainland Southeast Asia in Week 1 (17 – 23 October).

For temperature, cooler than usual temperature is expected over much of central and eastern Mainland Southeast Asia in Week 1 (17 – 23 October), while warmer than usual temperature is predicted to develop over much of Myanmar in Week 2 (24 – 30 October). Over parts of the southern Maritime Continent, cooler than usual temperature is predicted over the next fortnight (17 – 30 October).

A Madden-Julian Oscillation (MJO) signal propagated to the Western Pacific (Phase 6) by the middle of October. Models forecast the MJO signal to remain over the Western Pacific (Phases 6 and 7) during most of the forecast period. However, there is significant variation in the strength of the MJO signal among the models.

September 30, 2022

Subseasonal Weather Outlook (3 – 16 October 2022)

Issued: 30 September 2022
First forecast week: 3 October – 9 October
Second forecast week: 10 October – 16 October

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

For rainfall, wetter conditions are predicted over most of the southern ASEAN region in the next fortnight (3 – 16 October). Drier conditions are predicted over the western Maritime Continent in Week 2 (10 – 16 October).

For temperature, cooler than usual temperature is predicted over much of the central Maritime Continent in line with the wetter conditions in the next fortnight (3 – 16 October).

No clear Madden-Julian Oscillation (MJO) signal was present at the end of September. Most models forecast an MJO signal to emerge over the Maritime Continent (Phases 4 and 5) in Week 1 and propagate eastwards towards the Western Pacific (Phase 6).