Subseasonal Weather Outlook and Review

1.1    Inter monsoon conditions prevailed in the first half of November 2016. During this period, there was a gradual migration of the monsoon rain band from the northern ASEAN region to the near-equatorial region. In the Mekong sub-region, rainfall decreased gradually as the month progressed, and in the second half of the month, dry weather conditions were observed to have set in over the region. In contrast, wet weather conditions prevailed in the southern ASEAN region, particularly over Indonesia.

1.2    Over the Western Pacific Ocean, a tropical depression that developed to the southeast of central Philippines on 23 November 2016 intensified into Tropical Storm Tokage and made landfall over central Philippines on 25 November 2016. “Tokage’s” passage through the Philippines was brief as it northeast and moved over the South China Sea before dissipating over water on 27 November 2016. “Tokage” brought heavy rainfall and strong winds of up to 102km/h to areas along its path.

1.3    The Northeast Monsoon season onset in the ASEAN region in late November 2016. Between 28 and 30 November, the region experienced a monsoon surge episode where cold and strong northeasterly winds from a high pressure system over northern China surged into the South China Sea bringing widespread showers to the surrounding region, including Sarawak and the eastern coastal areas of Peninsular Malaysia.

1.4    For November 2016, above-normal rainfall was received in parts of the Mekong sub-region including Myanmar, north-eastern Thailand, Lao PDR and Vietnam. For the Philippines, near-normal to above-normal rainfall prevailed. Below-normal to near-normal rainfall prevailed over most parts of the southern ASEAN region including southern Thailand, Malaysia, Singapore, Brunei and Indonesia The regional rainfall distribution for November 2016 is shown in Fig. 1A.

2.1    In November 2016, hotspot activities in both the northern and southern ASEAN region remained largely subdued.

2.2    The Inter monsoon conditions in November 2016 brought an increase of rainfall over the southern ASEAN region, and the showers contributed to keep the hotspot activities over Sumatra and Kalimantan low. In the northern ASEAN region, hotspot activities were generally subdued on most days of the month and as the weather started to become drier, increase in hotspot activities were observed over parts of the Mekong sub-region towards the end of November 2016 with the onset of the Northeast Monsoon. Satellite images depicting some of the hotspot activities over parts of the ASEAN region during November 2016 are shown in Fig. 2A – Fig. 2E

3.   Status of El Niño/La Niña

1.1    Inter monsoon conditions prevailed in the first half of November 2016. During this period, there was a gradual migration of the monsoon rain band from the northern ASEAN region to the near-equatorial region. In the Mekong sub-region, rainfall decreased gradually as the month progressed, and in the second half of the month, dry weather conditions were observed to have set in over the region. In contrast, wet weather conditions prevailed in the southern ASEAN region, particularly over Indonesia.

1.2    Over the Western Pacific Ocean, a tropical depression that developed to the southeast of central Philippines on 23 November 2016 intensified into Tropical Storm Tokage and made landfall over central Philippines on 25 November 2016. “Tokage’s” passage through the Philippines was brief as it northeast and moved over the South China Sea before dissipating over water on 27 November 2016. “Tokage” brought heavy rainfall and strong winds of up to 102km/h to areas along its path.

1.3    The Northeast Monsoon season onset in the ASEAN region in late November 2016. Between 28 and 30 November, the region experienced a monsoon surge episode where cold and strong northeasterly winds from a high pressure system over northern China surged into the South China Sea bringing widespread showers to the surrounding region, including Sarawak and the eastern coastal areas of Peninsular Malaysia.

1.4    For November 2016, above-normal rainfall was received in parts of the Mekong sub-region including Myanmar, north-eastern Thailand, Lao PDR and Vietnam. For the Philippines, near-normal to above-normal rainfall prevailed. Below-normal to near-normal rainfall prevailed over most parts of the southern ASEAN region including southern Thailand, Malaysia, Singapore, Brunei and Indonesia The regional rainfall distribution for November 2016 is shown in Fig. 1A.

2.1    In November 2016, hotspot activities in both the northern and southern ASEAN region remained largely subdued.

2.2    The Inter monsoon conditions in November 2016 brought an increase of rainfall over the southern ASEAN region, and the showers contributed to keep the hotspot activities over Sumatra and Kalimantan low. In the northern ASEAN region, hotspot activities were generally subdued on most days of the month and as the weather started to become drier, increase in hotspot activities were observed over parts of the Mekong sub-region towards the end of November 2016 with the onset of the Northeast Monsoon. Satellite images depicting some of the hotspot activities over parts of the ASEAN region during November 2016 are shown in Fig. 2A – Fig. 2E

3.   Status of El Niño/La Niña