Eighteenth Session of the ASEAN Climate Outlook Forum (ASEANCOF-18)
24 and 26 May 2022, PAGASA
Consensus Bulletin for June-July-August (JJA) 2022 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 Eighteenth session of ASEANCOF (ASEANCOF-18) was organised by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) in collaboration with the ASMC and the ASEANCOF Working Group. Participants from the NMHSs of ASEAN Member States created a consensus forecast for the boreal summer monsoon 2022 in the ASEAN region. The consensus for June-July-August (JJA) 2022 outlook was achieved through an online session, which included presentations from different NMHSs, questionnaires, and discussions regarding the current climate conditions and predictions in the Southeast Asia region. 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. There was also a special focus on monsoon variability, with a presentation from the Regional Working Group on Asian-Australian Monsoon (AAM-WG).
Conditions and Outlook
Recent analyses of sea surface temperature (SST) anomalies over the equatorial Pacific show below average SSTs across the central and eastern tropical Pacific Ocean indicative of La Niña. The international climate outlooks predict that the La Niña is likely to weaken during JJA 2022, although still overall indicate La Niña conditions. After JJA 2022, most models predict the ENSO state to be either cool ENSO neutral or La Niña.
The current IOD state is neutral. Most models predict a negative IOD developing during JJA 2022, with some models predicting the said negative IOD to be strong.
The onset of the Southwest Monsoon season has been earlier than normal in many parts of Mainland Southeast Asia, and near normal in the Maritime Continent. Over much of Southeast Asia, the strength of the Southwest Monsoon is expected to be near normal or weaker than normal, based on model predictions.
Overall, the tropical cyclone frequency is expected to be near average in the Bay of Bengal, while below to near average around the South China Sea and in the Philippine Sea. As there is an expected weakening of La Niña in JJA 2022, no significant deviation from the climatology of tropical cyclone frequency is expected during the forecast period.
Taking into consideration the national level forecasts, the present state of the climate, and the forecasts available from the global prediction centres (GPCs), the ASEANCOF-18 agreed on the following consensus-based outlook for JJA 2022 in the ASEAN region:
Over much of the southern ASEAN region, near to above normal rainfall is predicted. Near to above normal rainfall is predicted over Brunei Darussalam and many parts of Malaysia, with above normal rainfall predicted most elsewhere. The exceptions include parts of the western and eastern Maritime Continent, where near to below normal rainfall is predicted.
Over much of the northern ASEAN region, a mix of below to above normal rainfall is predicted. Near to below normal rainfall is predicted over the western and southeast portion of Mainland Southeast Asia, and northwest Philippines. Near to above normal rainfall is predicted over portions of northeast and southern Mainland Southeast Asia, and southern Philippines. Elsewhere in the northern ASEAN region, near normal rainfall is predicted.
Near to above normal temperature is predicted over the ASEAN region. The highest likelihood of above normal temperature is over the southern Maritime Continent and Lao PDR, while near normal temperature is predicted over northern Myanmar, northern and central Viet Nam, and parts of the western Maritime Continent. An equal chance of near to above normal temperature is predicted over southern Myanmar, Thailand, Cambodia, southern Viet Nam, the Philippines, Malaysia, and Brunei Darussalam.
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 JJA 2022 Season
The following maps provide the probabilistic outlooks for JJA 2022 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, 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.