Monthly Archives: October 2019

October 31, 2019

Outlook for Land Fires and Smoke Haze Situation (1 – 15 November 2019)

Issued 31 October 2019

Hotspot activities in the ASEAN region are expected to be generally subdued. However, for the southern parts of Sumatra and Kalimantan, Java and parts of Lesser Sunda Islands, there may be isolated hotspot activities during periods of dry weather. The risk of transboundary haze affecting the region is expected to be low.

Subseasonal Weather Outlook (1 – 15 November 2019)

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

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

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.

October 22, 2019

Review of Land Fires and Smoke Haze Situation for First Fortnight of October 2019

1.1 During the fortnight, the hotspot activities in the northern ASEAN region were generally subdued.

1.2 The occurrence of showers in the equatorial ASEAN region helped to subdue the hotspot activities in many parts of Sumatra and Kalimantan. However, hotspots emitting moderate to dense smoke haze persisted in the southern parts of Sumatra and Kalimantan where drier-than-normal conditions prevailed. These hotspots were mostly detected in southern Sumatra (namely in the provinces of Jambi, South Sumatra and Lampung) and in South, East and Central Kalimantan.

1.3 Figures 4, 5 and 6 show satellite images over the ASEAN region in the first fortnight of October 2019.

Figure 1 Smoke haze from hotspots in Central Kalimantan (marked by blue dotted lines)

Figure 2 Smoke haze from hotspots in southern parts of Sumatra (marked by blue dotted lines)

Figure 3 Smoke haze emanating from hotspots in southern parts of Sumatra and Kalimantan (marked by blue dotted lines)

Figure 4 Distribution of hotspots detected based on NOAA-20 satellite surveillance and prevailing winds in the first half of October 2019 (Source of prevailing winds: JMA)

October 9, 2019

Review of Land Fires and Smoke Haze Situation for Second Fortnight of September 2019

1.1 In the first half of the fortnight, persistent hotspots with moderate to dense smoke haze continued to be detected in Sumatra (mainly in the provinces of Jambi, South Sumatra and Lampung), and in Kalimantan (mostly in South, Central and West Kalimantan). Extensive smoke haze from these hotspots was also blown by the prevailing winds to affect parts of Peninsular Malaysia, Singapore and western Sarawak.

1.2 With increased showers over parts of Sumatra and Kalimantan in the last week of the month, there was a significant improvement in the hazy conditions in the southern ASEAN region. Smoke haze from hotspots continued be observed in the southern ASEAN region but was mainly detected in the southern parts of Sumatra and Kalimantan.

1.3 In the northern ASEAN region, hotspot activities remained generally subdued during the fortnight.

Figure 1 Smoke haze from hotspots in Sumatra and Kalimantan spread to neighbouring areas including parts of Peninsular Malaysia and western Sarawak.

Figure 2 Moderate to dense smoke haze from persistent hotspots in Sumatra and Kalimantan was blown by prevailing winds to affect parts of Peninsular Malaysia, Singapore and western Sarawak

Figure 3 Increased showers over equatorial region in the last week of September 2019 helped subdue the smoke haze situation; Smoke haze from hotspots was confined to the southern parts of Sumatra and Kalimantan

Figure 4 Distribution of hotspots detected based on NOAA-20 satellite surveillance and prevailing winds in the second half of September 2019 (Source of prevailing winds: JMA)

Review of Regional Weather Conditions for Second Fortnight of September 2019

Print Version

1. Review of Regional Weather Conditions for Second Fortnight of September 2019

1.1 In the second half of September 2019, the prevailing winds over the southern ASEAN region were from the east or southeast, with weaker winds over the equatorial areas. In contrast, over the Mekong sub-region, the prevailing winds were generally from the northeast or east. During the period, anomalous westerly or northwesterly winds prevailed over the northern Philippines. This was influenced by the presence of Tropical Storms Tapah and Mitag over the western Pacific Ocean.

Figure 1 5000 ft average winds (left) and anomalies (right) for 16 – 30 Sep 2019 (Source: JMA)

Figure 2 Tracks of Tropical Storm Tapah (19 Sep – 23 Sep, 2019) and Tropical Storm Mitag (28 Sep – 4 Oct, 2019) (Source: JAXA)

1.2 The influence of these tropical storms also contributed to the above-average rainfall over northern Philippines in the second half of the month. Wetter-than-normal conditions prevailed over the Mekong sub-region except for parts of Thailand, northern Lao PDR and western Cambodia, where below-average rainfall was recorded. In the southern ASEAN region, the drier-than-normal conditions persisted into the second half of the month. Toward the end of September 2019, a shift in the monsoon rain band over the equatorial ASEAN region brought showers over northern Sumatra, Malaysia, Singapore and parts of Kalimantan. During the fortnight, the Madden-Julian Oscillation (MJO) was in Phases 8 and 1, and could have also contributed to the increased shower activities in the last week of the month.

Figure 3 Daily average rainfall for the ASEAN region in the second fortnight of September 2019. (Source: JAXA Global Satellite Mapping of Precipitation)

Figure 4 Percentage of average rainfall for 16 – 30 September 2019. The rainfall data may be less representative for areas with a less dense rainfall network. (Source: IRI NOAA/NCEP CPC Unified Precipitation Analyses)

Figure 5 The MJO phase diagram (blue for September 2019). The diagram illustrates the movement of the MJO through different phases, which correspond to different locations along the equator. The distance of the index from the centre of the diagram is correlated with the strength of MJO. When the index falls within the circle, the MJO is considered weak or indiscernible. (Source: Bureau of Meteorology)

1.3 Over the tropical Pacific Ocean, El Niño – Southern Oscillation (ENSO) remained neutral. In the Indian Ocean, the positive Indian Ocean Dipole (IOD) strengthened in the second half of September 2019. A positive IOD is typically associated with drier weather over the southern ASEAN region.

October 3, 2019

Alert20191003 – Downgrade of Alert Level 2 to Alert Level 1 for the southern ASEAN region

Downgrade of Alert Level 2 to Alert Level 1 for the southern ASEAN region

Increased shower activities over many areas of southern ASEAN region have contributed to a significant improvement in the hotspot and haze situation. Based on surveillance by the NOAA-20 satellite, 33 and 5 hotspots were detected in Sumatra, and 10 and 9 hotspots were detected in Kalimantan on 2 and 3 October 2019 respectively. The hotspots were detected mostly in southern Sumatra and the southern and eastern parts of Kalimantan.

In the coming days, the prevailing winds over the southern ASEAN region are forecast to be light and variable in direction. More showers can be expected over the region. However, some areas including the southern parts of Sumatra and Kalimantan, can still experience brief periods of dry weather and hotspot activities may still persist in these areas. The risk of transboundary haze is currently assessed to be low due to rainy conditions elsewhere in the region, and prevailing winds that are generally light and variable in direction.