Thirteenth Session of the ASEAN Climate Outlook Forum (ASEANCOF-13)

November 2019, Thai Meteorological Department in collaboration with the ASEAN Specialised Meteorological Centre (ASMC)

Consensus Bulletin for December-January-February (DJF) 2019-2020 Season

The ASEAN Climate Outlook Forum (ASEANCOF) is an avenue to collaboratively develop consensus-based seasonal climate outlooks and related information on a regional scale for Southeast Asia.

The forum outlook and its activities contribute significantly to one of the key roles of the ASEAN Specialised Meteorological Centre (ASMC), which is to conduct climate and seasonal prediction for ASEAN region through pooling the expertise of ASEAN National Meteorological Services.

The Thirteenth ASEANCOF (ASEANCOF-13) was organised by the Thai Meteorological Department in collaboration with Meteorological Service Singapore as host of the ASEAN Specialised Meteorological Centre.

Representatives from National Meteorological and Hydrological Services (NMHSs) of ASEAN Member States created a consensus forecast for the boreal winter 2019-2020 in the ASEAN region. The consensus for December-January-February (DJF) 2019-2020 outlooks was achieved through the Thirteenth ASEAN Climate Outlook Forum and Training in Bangkok, Thailand from 18 to 21 November 2019. The consensus was made based on presentations and discussions on current conditions and predictions for the Southeast Asia region. In particular, the forum took into account the significant influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate over Southeast Asia.

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Conditions and Outlook

Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific indicate slightly above average SSTs across most of the Pacific Ocean. The ENSO neutral conditions have been present since July 2019. The international climate outlooks predict ENSO neutral conditions are likely to continue during DJF 2019-2020. The present positive Indian Ocean Dipole (IOD) is expected to weaken in DJF 2019-2020. The Northeast monsoon for the southern half of the region is expected to be delayed due to the strong positive IOD at the start of the season.

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 2019-2020 for the Southeast Asia region:

RAINFALL

For the upcoming Northern Hemisphere winter season (December-January-February), near-normal conditions are expected over most parts of Mainland Southeast Asia, and parts of the equatorial region. However, there is a slightly enhanced probability of wetter than normal conditions over northern Vietnam, the eastern part of Malaysia, the eastern part of Celebes, Moluccas and northern part of Papua. There is a slightly increased probability of drier than normal conditions over the southern part of Myanmar, parts of Thailand (the northern, central, eastern and south-eastern of region), Philippines, northern and southern Sumatra, Java, the western part of Celebes, Bali, Nusa Tenggara, the southern part of Borneo and the southern part of Papua.

TEMPERATURE

Above normal temperatures are expected for most of Southeast Asia, apart from eastern and southern Myanmar, northern Thailand and northern Sumatra, where near normal temperatures are expected. For the regions with expected above normal temperature, the highest probability is over northern Vietnam, Lao PDR, Cambodia, northern Thailand and southern 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 Summer Monsoon outlook and further updates on the national scale, the relevant NMHSs should be consulted (see Annex B).

Consensus Maps for DJF 2019-2020

The following maps provide the probabilistic outlooks for DJF 2019-2020 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

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PROBABILISTIC TEMPERATURE OUTLOOK

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Meeting Documents

ASEANCOF-13 Outlook Bulletin

Acknowledgements

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 TMD for the administrative and funding support provided to the meeting.