Prolonged, intense heat expected from June to Oct, raising risk of haze, fires in south Asean
More prolonged and intense heat and dry weather are expected from June to October in the southern Asean region – which includes Singapore – with a higher risk of transboundary haze and fires, said the Asean Specialised Meteorological Centre (ASMC).
“With a high likelihood of El Nino conditions developing in the coming months, the dry season is expected to be more intense and prolonged compared to recent years and extend into October 2023,” added the Singapore-based ASMC in a statement on Monday.
ASMC serves as the Asean regional centre for monitoring and assessment of fires and haze, and provides early warning services for transboundary haze.
El Nino – the global weather phenomenon that brings hotter and drier weather to South-east Asia and Australia – is predicted to arrive in the second half of 2023.
A strong El Nino event in 2015 shrouded South-east Asia in thick haze, leading Singapore to close primary and secondary schools for a day in September that year. The weather phenomenon persisted through 2016, making that the hottest year on record, exacerbated by human-induced warming from greenhouse gases.
The last El Nino cycle – a weaker one in 2018 and 2019 – also led to transboundary haze, and Singapore experienced unhealthy air quality over a few weeks in 2019.
ASMC added that there is a higher risk of escalated hot spot activities and transboundary smoke haze in the southern Asean region between June and October than in the last three years, when the region experienced prolonged La Nina conditions.
La Nina, the sister phenomenon to El Nino, brings wetter and cooler conditions to the region.
“Early precautionary and mitigation measures are advised to prevent the occurrence of fires and transboundary haze in the region,” added ASMC.
The meteorological centre noted that current hot spot activities in the southern Asean region are still subdued, with 14 and 13 hot spots detected on May 27 and 28 respectively.
“A few localised smoke plumes were detected in parts of the region on some days in May 2023, but no transboundary smoke haze occurrence has been observed so far,” it said.
The southern Asean region includes Singapore, Malaysia, Indonesia, Brunei and southern Thailand.
ASMC also signalled the start of the dry season on Monday. Parts of South-east Asia have already been scorching under record heatwaves since April.
In Singapore, temperatures reached 37 deg C on May 13 in Ang Mo Kio, a joint all-time high matching the peak hit in Tengah in 1983.
“Since earlier this year, warmer subsurface ocean temperatures have been observed in the eastern tropical Pacific, which is an early sign that support El Nino conditions developing in the next few months.”
ASMC added that another phenomenon, called the positive Indian Ocean Dipole, which causes warmer sea surface temperatures in the western Indian Ocean, could develop in the next one to two months.
An El Nino event with the positive Indian Ocean Dipole could drive up heat and dry weather in the region.
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