Thread: Why Singapore and Southeast Asia could see a wetter, rainier end to 2024

Singapore's government issued flood risk alerts on Monday (Oct 14) as the inter-monsoon period brought heavy rains and lightning.


Throughout the rest of Southeast Asia, weather forecasters are predicting similarly wetter conditions for the next two months at least, possibly signalling a shift to the start of the La Nina phenomenon.

What is La Nina and how does it lead to heavier rain?


It's a pattern involving tropical Pacific sea surface temperatures, that usually persists for months to about a year, meteorological experts told CNA.


Under normal conditions, the sea in the Western Pacific region is cooler than the sea in the Eastern Pacific region, said Dr Wang Jingyu, an assistant professor of physical geography at the National Institute of Education (NIE).


Under La Nina conditions, the sea surface temperature in the Western Pacific region is warmer by 0.5 to 1 degree Celsius instead.


And the surface temperature of water is warmer, more of it evaporates. This increases moisture in the lower atmosphere, which in turn leads to more rain.


The reverse of La Nina is El Nino, which Singapore experienced from March to April. Here, sea surface temperature patterns are cooler in the Western Pacific and warmer in the Eastern Pacific.


The result is hotter and drier weather.

How long is La Nina expected to last?


La Nina conditions will likely run from October to November onwards, with most models predicting this will persist until early 2025, said the Asean Specialised Meteorological Centre earlier this month.


Above-normal rainfall is predicted for much of the southern region of Southeast Asia during this forecast period, the centre added.


The National Oceanic and Atmospheric Administration (NOAA) in the United States meanwhile is predicting a 60 per cent chance for La Nina to emerge by November and last through January to March next year, said Professor Matthias Roth from the National University of Singapore’s geography department.

What does it mean for Singapore and the region?


Dr Dhrubajyoti Samanta, a senior research fellow with the Earth Observatory of Singapore at Nanyang Technological University, pointed to the NOAA forecasting a weak La Nina in Southeast Asia.

This makes it "very likely" that it won't be very wet or of severe concern beyond a typical La Nina.


Such conditions could even be useful for groundwater recharge - where water infiltrates deeper soil layers - and agriculture; while improving air quality, said Dr Samanta.


But Prof Roth noted that a La Nina over the next few months would coincide with Northeast monsoon season, which is already the wettest part of the year.


Apart from cooler air temperatures, there's an increased likelihood of localised flooding when above-average rainfall coincides with periods of already high sea levels, such as during seasonal high tides, he said.


Dr Wang said some Southeast Asian countries could see a higher risk of flooding in low-lying areas with poor drainage, and landslides or mudslides in mountainous regions.


Apart from the threat to public health and lives, this can also disrupt planting and harvesting schedules or worse, destroy crops, thus reducing agriculture yields and resulting in economic loss.

For example, Malaysia's 2021 floods affected more than 10,000 hectares of farmland, causing rice yield to drop by more than 200,000 tonnes, Dr Wang pointed out.


It would take years to recover the infrastructural damage and rice production is Malaysia is still not at an optimal level, he added.


As it is, most countries in the Indochina peninsula are already dealing with the after-effects of deadly storms in recent months.


Typhoon Yagi brought powerful winds and torrential rainfall to Vietnam, Thailand, Laos and Myanmar in September, killing hundreds and damaging factories and farmland.


And the Philippines was hit by several deadly storms in recent months, including Typhoon Gaemi in July, Yagi in September and Krathon in October.

How should governments respond?


Preferably, proactively, experts said.


For example, early flood warnings issued on Monday by Singapore's national water agency PUB gave people time to prepare, said Dr Wang.


Governments should also conduct flooding preparedness exercises to ensure that emergency responders are ready to respond to any incidents, he suggested.


They should also inspect drainage infrastructure to ensure that it can handle the expected rainfall, and raise awareness about the potential impact of the weather.

What does it mean for long-term climate trends?


The projected La Nina to come is not quite comparable to what Southeast Asia experienced from 2020 to 2022, and 1998 to 2001 previously.


The more recent event led to "once in a century" flooding in Malaysia, causing more than 50 people deaths and several billion dollars in financial losses, said Dr Wang, adding that he would consider this an “extreme” scenario.


Nonetheless, experts noted that Singapore and wider Southeast Asia are experiencing more of both rainfall and warmer conditions due to climate change.


“Located in the deep tropics, Singapore used to be less prone to the effects of climate change compared to other mid-latitude countries," said Dr Wang.


"However, as global warming speeds up, we start to see more frequent occurrences of weather and climate extremes over the island.


“The previously known 'once in a century' events could become once in a decade, or even worse, once a year, in the next few years," he added.


"We need to take action. Every single effort to reduce carbon footprint still counts - before it’s too late.”


CNA Explains: Why Singapore and Southeast Asia could see a wetter, rainier end to 2024 - CNA

Of course it’s because of climate change

Throughout the rest of Southeast Asia, weather forecasters are predicting similarly wetter conditions for the next two months at least, possibly signalling a shift to the start of the La Nina phenomenon.

Meanwhile, in other, old news:

The La Nina climate pattern has begun affecting local weather, according to the Thai Meteorological Department. Although there is heavy rainfall in some areas, officials say water volume in the reservoirs of major dams may not be sufficient to meet requirements during the dry season that runs from November to April.

Thailand began experiencing La Nina in July and the pattern is likely to continue until early next year, the department’s weather forecasters say. It will lead to heavy rainfall across the country, alongside tropical storms in August and September.

C'mon chaps, think about what you're inviting in here.

Spamdeath is probably highlighting fifteen ten thousand word articles at this very moment.

Rich sodden Asians envy towelheads shock horror.
Sausage washed into turd filled sea in Wongamat Money Laundromat tragedy you heard it here fist.

Originally Posted by harrybarracuda

lthough there is heavy rainfall in some areas, officials say water volume in the reservoirs of major dams may not be sufficient to meet requirements during the dry season that runs from November to April.

How is that possible?

The water isn’t distributed evenly. Some reservoirs are full but others have little water and they aren’t connected. No way to distribute water for agricultural needs in areas that have insufficient amounts.

Originally Posted by misskit

The water isn’t distributed evenly. Some reservoirs are full but others have little water and they aren’t connected. No way to distribute water for agricultural needs in areas that have insufficient amounts.

Preparation and planning, Thai style.

You know well how that is.

Originally Posted by harrybarracuda

Nakhon Ratchasima, in the north-east, is facing a water shortage with all of its 27 reservoirs now less than half full.

Interesting. I need to look at a map to understand where all the water has gone. From my part of Isan, it mostly flows down to join the Mekong at Ubon Ratchatani. West of the Loei mounains it goes mostly south to Bangkok. Does it somehow all miss Korat? If only we had someone with a dog and local knowledge to give us some insight.

Originally Posted by cyrille

C'mon chaps, think about what you're inviting in here.

Spamdeath is probably highlighting fifteen ten thousand word articles at this very moment.

To be fair that happened as soon as misskit posted this article. Surprised he hasn’t kept to action already.

Originally Posted by Shutree

Does it somehow all miss Korat? If only we had someone with a dog and local knowledge to give us some insight.

Are you talking about me?

I can't speak for Nakhon Ratchasima province, but I've been home here here in the Meung for around seven weeks and whereas I constantly get rain forecast on my weather app, it almost never seems to happen. I'm aware that rain can be extremely localised here, but time and time again it seems to miss this area.

During all the flooding reported up north, I would say that for most of the time we have been watering the garden and have only received the very occasional heavy downpour.