Category Archives: Uncategorized

February 28, 2019

Subseasonal Weather Outlook (1 Mar – 15 Mar 2019)

Issued 28 Feb 2019
valid for weeks 1 and 2: 1 Mar – 15 Mar

Figure 1: Rainfall Outlook

Figure 2: Temperature Outlook

In the coming fortnight, the Philippines, Malaysia, southern Viet Nam, southern Thailand and northern Sumatra are expected to receive below average rainfall. Wetter-than-usual conditions are forecast over the southwestern parts of the southern ASEAN region (marked in green in Figure 1) in the first week of March, and may extend eastward in the second week. The higher-than-average rainfall can be attributed to the passage of the Madden-Julian Oscillation (MJO) during this period.

Warmer-than-usual conditions are expected to persist over Cambodia, Lao PDR, southern Thailand, Viet Nam, Peninsular Malaysia and northern Sumatra in the first fortnight of March.

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.

January 30, 2019

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

1.1 In the Mekong sub-region, prolonged dry weather led to an escalation of hotspot activities in Cambodia. A build-up of smoke haze was observed around persistent hotspot clusters in Cambodia and smoke haze was blown westward toward Thailand. In Thailand, isolated hotspots with localised smoke plumes were also observed. In the southern ASEAN region, hotspot activities were subdued under the prevailing wet conditions.

Figures 1: AQUA satellite image on 7 Jan 2019 shows moderate to dense smoke haze observed in Cambodia.

Figures 2: Himawari-8 satellite image on 13 Jan 2019 shows moderate smoke haze observed in Cambodia. Localized smoke plumes were also observed in the vicinity of isolated hotspots in northeastern Thailand.

Review of Regional Weather Conditions for First Fortnight of January 2019

Print Version

1. Review of Regional Weather Conditions for First Fortnight of January 2019

1.1 Northeast Monsoon conditions prevailed over the ASEAN region. In the Mekong sub-region, dry weather persisted over most parts of the region, except for some isolated showers that fell over coastal Viet Nam on a few days due to the strengthening of northeasterly and easterly winds over the South China Sea. Rainy conditions were also experienced in southern Thailand and northern Peninsular Malaysia due to the passage of Typhoon Pabuk during the first week of the month. This resulted in above-average rainfall over southern Thailand and northern Peninsular Malaysia.

1.2 There were scattered shower activities over the southern ASEAN region, and most parts of the region received average to above-average rainfall. However, there were some areas where below-average rainfall was received, namely parts of Malaysia, northern Sumatra, and Java.

1.3 The rainfall distribution and the percent of average rainfall for the first fortnight of January 2019 are shown in Figure 1 and 2.

Figure 1: Daily average rainfall for the ASEAN region in the first fortnight of January 2019. (Source: JAXA Global Satellite Mapping of Precipitation)

Figure 2: Percent of average rainfall for 1 – 15 January 2019. The rainfall data may be less representative for areas with a less dense rainfall network. Hatched areas indicate climatology dry mask (average daily rainfall below 1 mm). (Source: IRI NOAA/NCEP CPC Unified Precipitation Analyses)

1.4 In the northern ASEAN region, moderate to strong easterly winds prevailed over the South China Sea area. There were also anomalously southwesterly winds under the influence of the Typhoon Pabuk. In the southern ASEAN region, anomalous westerly winds were recorded.

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Figure 3: 5000 ft average winds (left) and anomalies (right) for 1 – 15 January 2019. (Source: JMA)

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Figure 4: Track of Typhoon Pabuk between 1 and 6 January 2019.

1.5 The sea surface temperature (SST) over the tropical Pacific Ocean is warmer than average, but temperatures remained in weak El Nino conditions and have weakened further. Prevailing atmospheric response, viz the cloudiness and trade winds over the tropical Pacific Ocean have remained neutral.
1.6 During the fortnight, moderate to strong Madden Julian Oscillation (MJO) signals propagated through Phase 6 – 8. The signal weakened towards the end of the second week of the fortnight. Although MJO signals in Phase 6 – 8 typically brought dry weather to the region, the MJO did not significantly influenced the weather in Southeast Asia during this period.

Figure 5: The MJO phase diagram for Jan 2019 (blue). 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)

October 16, 2018

Outlook for Land Fires and Smoke Haze Situation (16 – 31 Oct 2018)

Outlook for Land Fires and Smoke Haze Situation (16- 31 Oct 2018)

Issued 15 October 2018

Hotspot activities in the northern ASEAN region are expected to remain subdued. In the southern ASEAN region, sporadic hotpot activities are expected during brief periods of dry weather.

June 7, 2017

Start of Dry Season – 07062017

Start of dry season for the southern ASEAN region

The Southwest Monsoon onset in the region in late May 2017. Over the past few days, the region including Sumatra and Kalimantan has been experiencing dry weather conditions. The number of hotspots in Sumatra and Kalimantan has remained low but is expected to increase as the dry season progresses. Based on surveillance by the NOAA-19 satellite, 12 and 14 hotspots were detected in Sumatra on 6 and 7 June 2017 respectively.

The prevailing Southwest Monsoon is expected to strengthen and persist over the next few months. During this period, extended periods of drier weather can be expected, which could lead to elevated hotspot activities in the fire-prone areas.

June 23, 2015

Alert 1 250615 Start of Dry Season Southern ASEAN

The dry season for the southern ASEAN region has started

The Southwest Monsoon has onset in the region in early June 2015. In recent days, the region including Sumatra and Kalimantan have been experiencing dry weather conditions, signalling the start of the traditional dry season in the southern ASEAN region.

The prevailing Southwest Monsoon is expected to persist over the next few months. The prevailing El Nino could also exacerbate the dry season. During this period, extended periods of drier weather can be expected, which could lead to elevated hotspot activities in the fire-prone areas.

May 8, 2015

FAQ – Regional climate

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March 27, 2015

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January 22, 2015

Alert_220115

Upgrade of Alert Level 1 to Alert Level 2 for northern ASEAN region

The prevailing dry weather conditions in the northern ASEAN region have led to a build-up of smoke haze over parts of the region in recent days. There has been an escalation in hotspot activities with 1321 and 1118 hotspots detected on 20 and 21 January 2015 respectively in Thailand, Cambodia, Vietnam and Lao PDR.

In Cambodia, smoke haze from persistent clusters of hotspots has been observed in large areas particularly in the northern and central parts of the country. In Thailand, scattered hotspots were detected mainly in the northern and central parts of the country.

With the current dry season in the northern ASEAN region expected to continue into March/April 2015, further escalation of hotspot activities can be expected in the region in the coming weeks.