11th ASEAN COF (29 Oct – 1 Nov 2018, Malaysia)
The Eleventh ASEAN Climate Outlook Forum (ASEANCOF-11) was held in Kuala Lumpur, Malaysia from 29 October – 01 November 2018. This forum was organised by the Malaysian Meteorological Department in collaboration with the ASEAN Specialised Meteorological Centre (ASMC). The ASEANCOF was started in 2013, as part of the World Meteorological Organisation/Climate Information and Prediction Services (WMO/CLIPS) project for Regional Climate Outlook Forum (RCOFs) in cooperation with National Meteorological and Hydrological Services (NMHSs). It is a platform for regional NMHSs and international partners such as the WMO Global Producing Centres (GPCs) to collaboratively develop a consensus-based seasonal climate outlook and related information on a regional scale. It also provides an avenue for NMHSs to share best practices and get updated on the latest scientific advances in seasonal predictions. The ASEANCOF-11 event was co-funded by the ASEAN Science Technology and Innovation Fund (ASTIF), World Meteorological Organization (WMO) through its partners, and Malaysian Meteorological Department.
The forum’s outlook and activities contribute significantly to one of the key roles of the ASMC, which is to conduct climate and seasonal prediction for ASEAN region through pooling the expertise of ASEAN NMHSs. The Forum also supports the activities of the Southeast Asia Regional Climate Centre Network (SEA RCC-Network) – which entered the demonstration phase on 7 November 2017 – by providing the consensus outlook as well as the platform to discuss issues on provision of climate services in the Southeast Asia region.
The forum was attended by representatives from the region’s NMHSs, i.e. Brunei, Indonesia, Lao, Malaysia, Myanmar, Philippines, Singapore, Thailand, and Vietnam who presented on their national rainfall and temperature outlook for the upcoming December 2018 – February 2019 (DJF 2018-19) boreal winter monsoon season. The NMHSs were joined by experts from the Bureau of Meteorology, Australia (BoM), China Meteorological Administration (CMA), European Centre for Medium-range Weather Forecast (ECMWF), Japan Meteorological Agency (JMA), UK MetOffice (UKMO), and the WMO Lead Center for Long Range Forecast Multi-Model Ensemble (WMO LC-LRFMME), who presented on the regional outlook from their respective models. To provide scientific basis for the outlook of DJF 2018-19, the Forum also assessed the various global and regional climatic factors that influence the DJF season in the area. In particular, the Forum took into account the influence on the climate over Southeast Asia from the El Niño Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), tropical cyclones, and the monsoon circulation patterns.
Three regional end-user agencies from the water resources management and agricultural sectors were also invited, namely, the ASEAN Hydroinformatics Data Centre (AHC), the International Rice Research Institute (IRRI), and the Mekong River Commission (MRC). The agencies shared on their activities that serve the respective communities and, in line with this year’s meeting theme, they shared on their requirements for seasonal predictions and monitoring of extreme weather and climate.
Conditions and Outlook
The ENSO was in warm-neutral conditions in late October 2018. There is a 70% chance for an El Niño event to develop in the season DJF 2018-19 but its intensity is unlikely to be strong, and more likely to be weak than moderate. The Indian Ocean Dipole (IOD) index was also slightly positive (warmer western Indian ocean SST, and cooler eastern Indian Ocean SST). But the IOD is predicted to be neutral in DJF 2018-19.
For monsoon activity, due to warmer conditions predicted over East Asia in the DJF 2018-19 season, a weaker high pressure system is generally expected and consequently may result in weaker northeast monsoon winds. This coupled with potential changes in the Walker Circulation due to El Niño, convective rainfall activity is expected to be relatively suppressed in general for the region in DJF 2018-2019. Typically, during El Niño events, tropical cyclone activity in the Southwest Pacific tends to be less active (less frequent). However, as the El Niño event is not expected to be a strong one, and models are not showing significantly reduced tropical cyclone activity in the DJF 2018-19; a near-normal situation is more likely.
Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from GPCs and other global centres, the forum agreed on the following consensus-based outlook for DJF 2018-19 for the Southeast Asia region:
For the upcoming boreal winter monsoon season (DJF 2018-19), below-normal conditions are favoured over parts of the Philippines, southern Vietnam, northern Laos, central and southern Myanmar, southern Thailand, and northern Borneo. Elsewhere near- to above-normal rainfall conditions are favoured, with relatively less confident probabilities.
Above-normal temperatures are favoured over much of the Southeast Asia region for the upcoming boreal winter monsoon season (DJF 2018-19). Near-normal to above-normal temperatures are favoured over southern Vietnam, Brunei, and northern-central Myanmar.
Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the Northern Hemisphere winter monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).
Consensus Maps for DJF 2018-2019
The following maps provide the probabilistic outlooks for DJF 2018-19 season in terms of tercile categories of “Above-Normal” (AN: upper tercile), “Near-Normal (NN: middle tercile) and “Below-Normal” (BN: lower tercile).
PROBABILISTIC RAINFALL OUTLOOK
PROBABILISTIC TEMPERATURE OUTLOOK
The Forum would like to convey its appreciation to the National Meteorological Services of the ASEAN Member States for sharing 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. The Forum would also like to thank the ASEAN Secretariat, the WMO Secretariat, and the local organising committee from MMD for the administrative and funding support provided to the meeting.