Nineteenth Session of the ASEAN Climate Outlook Forum (ASEANCOF-19)
21 to 25 Nov 2022, MSS
Consensus Bulletin for December-January-February (DJF) 2022/2023 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. The forum’s 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 the Association of Southeast Asian Nations (ASEAN) region through pooling the expertise of ASEAN National Meteorological and Hydrological Services (NMHSs). In 2021, the ASEANCOF Working Group was established with the goal to guide and support the long-term development of ASEANCOF, in particular with regard to the implementation of objective outlooks.
The Nineteenth session of ASEANCOF (ASEANCOF-19) was organised by Meteorological Service Singapore (MSS) in collaboration with ASMC and the ASEANCOF Working Group. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal winter monsoon 2022-2023 in the ASEAN region. The consensus for the December-January-February (DJF) 2022-2023 outlook was achieved through an online session, which included presentations from different Global Producing Centres (GPCs), NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions for Southeast Asia. In particular, ASEANCOF considered the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate system over Southeast Asia. The theme of ASEANCOF-19 was climate services for agriculture. On the last day of ASEANCOF-19, a webinar was held involving both producers and users of seasonal outlooks, including presentations on using climate services for agriculture.
Conditions and Outlook
Recent analysis of sea surface temperature (SST) anomalies over the equatorial Pacific shows below-average SSTs across the central and eastern equatorial Pacific Ocean indicative of La Niña.
The international climate outlook predicts that the La Niña is likely to weaken during DJF 2022/2023, although overall still indicates La Niña conditions. After DJF 2022/2023, most models predict the ENSO state to gradually return to neutral.
While a negative Indian Ocean Dipole (IOD) was present for much of the second half of 2022, models predict the IOD to return to neutral by the end of 2022.
The onset of the Northeast monsoon season has been or is expected to be near average in many parts of the region. Over much of Southeast Asia, the strength of the Northeast monsoon is expected to be near average or stronger than average, based on model predictions and supported by the La Niña conditions.
Overall, the tropical cyclone frequency is expected to be near average in the Bay of Bengal and around the South China Sea and the Philippine Sea.
Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the GPCs, ASEANCOF-19 agreed on the following consensus-based outlook for DJF 2022/2023 over the ASEAN region:
Over the Maritime Continent, a mix of below to above normal rainfall is predicted. In particular, near to above normal rainfall is most likely over much of the Philippines and Brunei Darussalam, while near normal rainfall is most likely over much of Malaysia and Singapore.
Over Mainland Southeast Asia, below normal rainfall is most likely over northern parts, including northern Myanmar as well as northern Viet Nam. Above normal rainfall is most likely over southern and southeastern Mainland Southeast Asia, including southern Thailand, parts of Cambodia, and southern Viet Nam. Elsewhere, near normal rainfall is predicted.1
1This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.
Over the ASEAN region, a mix of below- to above-normal temperature is predicted. Above normal temperature is most likely over parts of Myanmar, northwestern Viet Nam and the eastern Maritime Continent, while below to near normal temperature is most likely over southeastern Mainland Southeast Asia. Elsewhere, near or near to above normal temperature is predicted.2
2This is based on the climatology period 1991-2020. However, at the national level, Myanmar is using the 1981-2010 climatology as their base period.
Refer to Annex A for reference on what is meant by “above, near, or below normal” in the outlook. For more information on the boreal (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 2022/2023 Season
The following maps provide the probabilistic outlooks for DJF 2022/2023 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
ASEANCOF would like to convey its appreciation to the NMHSs of the ASEAN Member States for sharing their national level forecasts, the GPCs, the Southeast Asia Regional Climate Centre – Network, RIMES, UN ESCAP, and other partners of ASEANCOF for sharing their products and expertise, and the World Meteorological Organization Regional Office in Asia and the Southwest Pacific (WMO-RAP) for their continued support of ASEANCOF.