Review of Land Fires and Smoke Haze Situation for First Fortnight of August 2019
1.1 Under the prevailing dry conditions, significant hotspot activities persisted in Sumatra and Kalimantan. Moderate to dense smoke haze continued to emanate from persistent hotspot clusters detected in Riau and Jambi. Isolated hotspots with smoke plumes were also detected in South Sumatra. The prevailing southerly and southeasterly winds transported some smoke haze toward the Straits of Malacca.
1.2 In Kalimantan, hotspot activities with smoke haze continued to be detected in Central, West and South Kalimantan. In particular, moderate to dense smoke haze was observed from the persistent hotspot clusters in West Kalimantan, and smoke haze emanating from these hotspots was blown by the prevailing southeasterly winds into Sarawak. Moderate to dense smoke haze was also observed near Palangkaraya in Central Kalimantan.
1.3 Isolated hotspots with smoke plumes were also detected in Sarawak. For a few days, smoke plumes from hotspots in Miri, Sarawak were blown eastwards toward Brunei.
Figure 1: Himawari-8 satellite image showing moderate to dense smoke haze from hotspots detected in central and southern Sumatra.
Figure 2: Himawari-8 satellite image showing moderate to dense smoke haze from persistent hotspots near Palangkaraya, Central Kalimantan. Smoke plumes were also observed in West and South Kalimantan. Smoke haze in West Kalimantan was blown into Sarawak by the prevailing winds. In Sarawak, smoke plumes from hotspots in Miri were blown eastwards toward Brunei.
Review of Regional Weather Conditions for First Fortnight of August 2019
Review of Regional Weather Conditions for First Fortnight of August 2019
1. Review of Regional Weather Conditions for First Fortnight of August 2019
1.1 Southwest Monsoon conditions prevailed in the first half of August 2019. In the northern ASEAN region, the prevailing winds were blowing mostly from the southwest or west. During the fortnight, the westerly winds were anomalously strong and stronger-than-usual winds were also observed over the Philippines. The stronger winds could have been due to the presence of Tropical Storm Wipha over the South China Sea in early August 2019 and Typhoon Lekima over the western Pacific Ocean from 4 August till 12 August 2019. Wipha made landfall in northern Viet Nam on 3 August, bringing heavy rain and flash floods to the area. The rainband associated with the storms contributed to the well above-average rainfall recorded over northern Philippines and many parts of the Mekong sub-region.
1.2 In the southern ASEAN region, winds were blowing mainly from the southeast or southwest. The dry conditions observed since July 2019 persisted into the first half of August 2019. Well below-average rainfall was observed over many areas. The dry conditions could be attributed partly to the presence of the Indian Ocean Dipole (IOD) in the positive phase.
Figure 1: 5000 ft average winds (left) and anomalies (right) for 1 – 15 August 2019 (Source: JMA)
1.3 There were signs of the Madden-Julian Oscillation (MJO) appearing briefly in Phases 3 and 4 (6th – 11th August), although MJO activity was insignificant by the end of the fortnight. The enhanced shower activities in the northern ASEAN region were consistent with the typical rainfall response from MJO in Phases 3 and 4 during this period.
Figure 4: The MJO phase diagram (blue for August 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)
1.4 In the first fortnight of August 2019, the El Niño – Southern Oscillation (ENSO) remained neutral (i.e neither El Niño nor La Niña conditions).
August 18, 2019
Outlook for Land Fires and Smoke Haze Situation (16 – 31 August 2019)
Outlook for Land Fires and Smoke Haze Situation (16 – 31 August 2019)
Issued 18 August 2019
With dry weather persisting over the southern ASEAN region, a further deterioration of the haze situation in the fire-prone areas can be expected. The risk of transboundary haze occurrence in the region remains high. In the northern ASEAN region, hotspot activities are expected to remain low.
Subseasonal Weather Outlook (16 – 31 August 2019)
Subseasonal Weather Outlook (16 – 31 August 2019)
Issued 18 August 2019
Valid for weeks 3 and 4: 16 August – 31 August
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.
August 10, 2019
Review of Land Fires and Smoke Haze Situation for Second Fortnight of July 2019
Review of Land Fires and Smoke Haze Situation for Second Fortnight of July 2019
1.1 In the second half of July 2019, dry weather persisted in the southern ASEAN region. This contributed to a further escalation of hotspot activities. Persistent hotspot clusters with smoke plumes and haze were observed, particularly in central and southern Sumatra, and in Kalimantan. Some of the smoke haze from hotspots in West Kalimantan was observed to be blown by the prevailing winds toward Sarawak. Smoke haze from hotspots in Riau, central Sumatra were observed to be blown toward Peninsular Malaysia. In the northern ASEAN region, hotspot activities were generally subdued by the prevailing rainy weather.
Figure 1: Persistent hotspot clusters with smoke haze (yellow dotted lines) in Sumatra
Figure 2: Smoke haze (yellow dotted lines) from hotspots in parts of Kalimantan. Some haze from West Kalimantan blown toward Sarawak
Review of Regional Weather Conditions for Second Fortnight of July 2019
Review of Regional Weather Conditions for Second Fortnight of July 2019
1. Review of Regional Weather Conditions for Second Fortnight of July 2019
1.1 Southwest Monsoon conditions continued to prevail in the second half of July 2019. The prevailing winds over the ASEAN region were blowing mainly from the southeast or southwest. During this period, rain bands associated with Tropical Storm Danas and Tropical Storm Wipha, which developed over the Philippine Sea and the South China Sea respectively, brought rainy weather to the northern ASEAN region. Above average rainfall was recorded in some parts of the northern ASEAN region.
1.2 In the southern ASEAN region, drier-than-normal conditions persisted over Peninsular Malaysia, Sumatra, Java and parts of Kalimantan. These conditions could be partly attributed to the presence of the Indian Ocean Dipole (IOD) which is currently in its positive phase.
Figure 1: 5000 ft average winds (left) and anomalies (right) for 16 – 31 July 2019 (Source: JMA)
Figure 2: Tracks of Tropical Storm Danas and Tropical Storm Wipha
1.3 The Madden-Julian Oscillation (MJO) was in Phase 1 and became insignificant towards the last week of the month. The MJO did not have a significant impact on the weather over the region during the past fortnight.
Figure 5: The MJO phase diagram (green for July 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)
1.4 In the tropical Pacific Ocean, there was further cooling of the surface and there was no significant atmospheric coupling. The El Niño – Southern Oscillation (ENSO) remained neutral in the second half of July 2019.
August 1, 2019
Alert20190801 – Activation of Alert Level 2 for the Southern ASEAN Region
Activation of Alert Level 2 for the southern ASEAN region
In recent days, there has been an escalation in hotspot activities and a deterioration in the haze situation in parts of the southern ASEAN region. Persistent hotspot clusters were detected in Riau and Jambi provinces in Sumatra and Central Kalimantan. Moderate to dense smoke haze has been observed to emanate from the hotspot clusters, giving rise to significant accumulation of smoke haze over these areas. The smoke haze from hotspots in Riau and Jambi is being blown by the prevailing southerly and southeasterly winds toward the Strait of Malacca.
Based on surveillance by the NOAA-19 satellite, 21 and 3 hotspots were detected in Sumatra, and 38 and 39 hotspots were detected in Kalimantan on 31 July and 1 August 2019 respectively. The low hotspot counts detected in Sumatra were in part due to partial satellite pass.
To provide advance information on the potential occurrence of transboundary haze to facilitate early mitigation measures, ASMC takes into consideration factors including forecast of meteorological conditions (rainfall and prevailing winds, etc), smoke haze density, and hotspot density and location, in addition to hotspot count when assessing the risk of transboundary haze occurrence. In view that the prevailing dry weather in the southern ASEAN region is expected to persist in the coming weeks and the winds are forecast to continue blowing from the southeast or southwest, ASMC assessed that there could be a further escalation of hotspot activities and an increase in the risk of transboundary haze occurrence.
Outlook for Land Fires and Smoke Haze Situation (1 – 15 August 2019)
Outlook for Land Fires and Smoke Haze Situation (1 – 15 August 2019)
Issued 1 August 2019
With drier and warmer than average conditions forecast over the southern ASEAN region, an escalation of hotspot activities can be expected, particularly over the fire-prone provinces in Sumatra and Kalimantan. This may contribute to an increase in the risk of transboundary haze occurrence in the region. In the northern ASEAN region, hotspot activities are expected to remain subdued due to prevailing rainy conditions.
Subseasonal Weather Outlook (1 – 15 August 2019)
Subseasonal Weather Outlook (1 – 15 August 2019)
Issued 1 August 2019
Valid for weeks 1 and 2: 1 August – 15 August
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.