December 23, 2015
The traditional dry season in the northern ASEAN region has started
In the past week, ASMC monitoring has detected an increase in hotspot activities in the Mekong sub-region, mainly in Thailand and Cambodia. The prevailing Northeast Monsoon conditions are expected to strengthen and persist for the next few months, bringing drier weather conditions to the northern ASEAN region. An increase in hotspot activities can be expected particularly during persistent dry periods.
December 9, 2015
1.1 The Inter-monsoon season, which is characterised by winds that are light and variable in direction and diurnal shower activities, prevailed in November 2015 before transiting into the Northeast Monsoon towards the end of the month. Both the northern and southern ASEAN regions experienced increased shower activities and wet weather conditions prevailed for most parts of the month.
1.2 The El Niño strengthened further in November 2015. However, as the impact of El Niño was usually less significant during the boreal winter season, drier than usual weather conditions were experienced mainly in the Philippines. Near-normal rainfall was received mainly over the northern ASEAN region. Above-normal rainfall was also received in the near-equatorial region especially in parts of Peninsular Malaysia, Sumatra and parts of Borneo island. The regional rainfall distribution for November 2015 is shown in Figure Fig. 1A.
2.1 In the northern ASEAN region, hotspot activities continued to be subdued by shower activities. There were some isolated hotspots detected towards the end of the November 2015 as dry weather conditions in the region started to set in.
2.2 The hotspot activities in the southern ASEAN region eased gradually in November 2015 as increased shower activities over most parts of the region helped to subdue the fires. In particular, the smoke haze in Kalimantan dissipated rapidly in early November 2015 after days of persistent heavy showers over hotspot areas.
2.3 Smoke haze in Sumatra however persisted slightly longer as the showers fell mostly away from the hotspot areas. Moderate smoke haze and scattered hotspots were observed in South Sumatra and these persisted into the second week of November 2015. The haze situation improved rapidly in the second half of November with the occurrence of more showers over the southern ASEAN region. This brought an end to the Southeast Asia smoke haze event that started in late August 2015. Satellite images depicting some of the hotspot activities over the ASEAN region in October 2015 are shown in Figs. 2A to 2E.
Fig. 2A: AQUA satellite image on 1 November 2015 shows some smoke haze observed in central Kalimantan following the increase in shower activities in late October 2015.
Fig. 2B: AQUA satellite picture on 3 November 2015 shows moderate smoke haze observed in parts of central and southern Sumatra.
Figure 2C: AQUA satellite image on 14 November 2015 shows smoke haze in Sumatra subdued with the increase in shower activities.
Fig. 2D: AQUA satellite image on 23 November 2015 shows the dry weather conditions over the Mekong-sub region.
Fig. 2E: AQUA satellite picture on 24 November 2015 shows widespread shower activities over the Borneo island.
2.3 The hotspot charts for November 2015 for
Fig. 2F: Hotspot Counts in Cambodia, Lao PDR, Thailand, Vietnam, Myanmar for November 2015.
Fig 2G: Hotspot Counts in Sumatra, Borneo and Peninsular Malaysia for November 2015.
3.1 The mature El Niño in the tropical Pacific Ocean continues to be at a strong level. The sea-surface temperatures are similar to the 1982-83 and 1997-98 strong El Niño events.
3.2 Atmospheric conditions in the ASEAN region continue to show a clear response to the strong El Niño conditions. Large-scale drier-than-normal conditions have been observed particularly in the southern and eastern parts of the ASEAN region. The consensus forecast based on assessments from international climate models and expert opinion suggests that El Niño conditions to continue through the first quarter of 2016. The strength of El Niño conditions is likely to peak in December 2015 and is expected to gradually decay in 1Q 2016.
3.3 Typically the impact of El Niño for the Southeast Asia region is drier than average rainfall conditions, especially for the southern parts of the ASEAN region during June to October. More locally-specific impact differs from place to place and for different seasons.
3.4 The region is currently in the Northeast Monsoon season (late Nov – Mar). The impact of El Niño is usually less pronounced during the Northeast Monsoon season as compared to the Southwest Monsoon season (Jun – Sep).
December 5, 2015
The Fifth ASEAN Climate Outlook Forum (ASEANCOF-5) was organised in Singapore from 18-19 November 2015 by the Meteorological Service Singapore (MSS), as host of the ASEAN Specialised Meteorological Centre (ASMC). This event was supported and co-sponsored by the World Meteorological Organization (WMO) and the US Agency for International Development (USAID). ASEANCOF-5 was attended by the National Meteorological Services (NMSs) of all 10 ASEAN Member countries: Brunei, Cambodia, Indonesia, Lao, Malaysia, Myanmar, Philippines, Singapore, Thailand, and Vietnam. The meeting was also attended by experts from the WMO Global Producing Centres (GPC): Bureau of Meteorology (BoM) Australia, China Meteorological Administration (CMA), European Centre for Medium-range Weather Forecasts (ECMWF), Japan Meteorological Agency (JMA), National Centers for Environmental Protection (NCEP, NOAA), WMO Lead Center for Long Range Forecast Multi-Model Ensemble (WMO LC-LRFMME), as well as the APEC Climate Centre (APCC), the International Research Institute for Climate and Society (IRI), and the Regional Integrated Multi-Hazard Early Warning System for Africa and Asia (RIMES). End-user representatives from the hydrological sector, coordinated by the Global Water Partnership South East Asia (GWP-SEA), and from the disaster-risk management agencies, coordinated by the ASEAN Coordinating Centre for Humanitarian Assistance, (AHA Centre) were also present.
For the upcoming Northern Hemisphere winter monsoon season (Dec-Jan-Feb), there is a strongly enhanced probability of below normal rainfall over the Philippines and the north-eastern part of Borneo Island. Over the eastern Maritime Continent and over the northern part of Mainland Southeast Asia, there are slightly enhanced probabilities of above normal rainfall. Elsewhere over the region, there are slightly enhanced probabilities for normal or below normal rainfall.
Above normal temperatures are very likely over much of the Southeast Asia region for the upcoming Northern Hemisphere winter monsoon season (Dec-Jan-Feb), with the highest probabilities over the central and western Maritime Continent.
The forum would like to thank the National Meteorological Services of the ASEAN Member countries for conveying their national-level forecasts, the Global Producing Centres and other participating international climate modelling centres for their products and expertise made available for this climate outlook forum, as well as the participants from the end-user communities coordinated by GWP-SEA and AHA Centre for their contributions. The forum would also like to thank the WMO Secretariat and the USAID for providing support and sponsorship for this event, and to IRI and APCC for coordinating the Pre-COF training workshop.
