The second monsoon surge may again scupper weekend plans, and commuters should avoid flood-prone areas. - Photo: ST
SINGAPORE: Another weekend of non-stop, islandwide downpours is expected from Friday (Jan 17) to Sunday (Jan 19) as the year’s second monsoon surge descends over the Republic.
Coming just days after the first episode ended on Jan 13, the second monsoon surge may bring windy and cooler conditions with occasional spells of moderate to heavy thundery showers over Singapore and the vicinity, said the National Environment Agency’s (NEA) Meteorological Service Singapore in its fortnightly weather outlook on Jan 16.
Coastal areas could see more flash flooding during this weekend’s monsoon surge, as tides are expected to be higher in the coming weekend compared with the previous surge.
During periods of seasonal high tides, it is common for low-lying areas along East Coast Park to get flooded even without incessant rain.
High tide at East Coast Park Area B at 12.01pm on Jan 15, 2025, causing seawater to overflow the banks of a drain.
There is a high tide of 3.2m at 11.35am on Jan 15, 2025, according to NEA.
Tide levels of 3m and above are considered higher than normal, according to PUB.
During high tide periods, water level can get quite high and seawater can overflow to the surrounding areas especially when combined with heavy rainfall.
Spring tides are a natural phenomenon that happens when the Sun, Moon and Earth are aligned, resulting in the gravitational pull of the Sun to be added to that of the Moon's.
On Jan 17, the tides are expected to reach up to 3.2m in the afternoon, according to information from the Maritime and Port Authority of Singapore, published on NEA’s website.
On Jan 18, the tides could reach 3.1m in the afternoon.
The highest tide during the Jan 10 to 13 monsoon surge was 2.9m.
In a Facebook post on Jan 16, national water agency PUB said high tides coupled with heavy rainfall could result in high water levels in coastal canals.
“PUB will monitor the forecast closely and issue flood warnings as needed,” it added.
Temperatures are expected to dip to around 22 deg C on the first few days of the next two weeks, coinciding with the monsoon surge. After that, temperatures are forecast to range between 24 deg C and 34 deg C on most days, said MSS.
Overall, the rainfall for the second half of January is expected to be above average over most parts of the island.
The last episode of incessant rain sent temperatures plunging to 21.6 deg C in Newton, and came with strong wind gusts and broke records for rainfall in January. Flash flooding occurred, trees fell and potholes exposed. Flights were delayed and also diverted to neighbouring airfields.
On the evening of Jan 10, a stretch of Jalan Seaview in Mountbatten was affected by flash floods because the deluge coincided with a high tide of 2.8m. This temporarily overwhelmed an adjacent canal and surrounding roadside drains.
Singapore is currently in the wet phase of the north-east monsoon – which tends to last from December to January – and spells of monsoon surges are common during this season.
A monsoon surge refers to bursts of cold air from the north-east, such as central Asia, which flows over the South China Sea, before bringing widespread rainfall, strong winds and cooler weather to Singapore.
When regions up north, such as Siberia, experience extremely cold weather in the winter months, the cold air occasionally sweeps southwards to the South China Sea, and is blown towards the tropics.
The air then warms and picks up moisture, leading to the formation of dense rain clouds. This brings increased rainfall near the equator.
Singapore experiences two to four monsoon surges each year, on average.
On Jan 10, the deluge on Pulau Tekong was more than double the average amount of rain that fell that day across Singapore’s 32 weather stations. The offshore island recorded 241.8mm of rain, surpassing the previous high of 238.2mm recorded on Jan 30, 2011, on Pulau Ubin.
Overall, more rain fell in Singapore during this period than the amount of rain that usually falls for the whole of January, and the Meteorological Service Singapore said the recent monsoon surge was one of the longer and more intense surge events in recent years.
To prepare for the monsoon season, PUB has been handing out protection devices and barriers to flood-prone houses and businesses. PUB’s Quick Response Teams are deployed to flood-risk locations and places where flash floods occur.
PUB contractors prepared with generators along Tanjong Katong Road South, ready to pump out excess water overflowing in drain in case of heavy rainfall and high tide at 11.13am on Jan 14, 2025.
Previously, flooding occurred along a stretch of Jalan Seaview and Mountbatten Road on the evening of Jan 10 because of heavy rain coinciding with a high tide of 2.8m that temporarily overwhelmed the adjacent canal and surrounding roadside drains.
PUB urged people to subscribe to PUB Flood Alerts on Telegram and to download the myENV app.
Flash floods in Singapore can occur during periods of intense rain, during seasonal high tides, and when both events happen concurrently.
To help the country better prepare for such double whammy events, PUB has also been developing a flood model, which is capable of simulating and evaluating inland and coastal floods in tandem.
Coastal floods caused by intense rainfall and high tide may offer a glimpse of what flooding could look like in Singapore amid future sea-level rise and climate change.
Sluice gate, water level sensors and CCTV camera in a canal along Tanjong Katong Road South to monitor the water flowing into the drains and canals in the areas around Tanjong Katong Road, Jalan Seaview and Mountbatten Road at 10.34am on Jan 14, 2025.
Previously, flooding occurred along a stretch of Jalan Seaview and Mountbatten Road on the evening of Jan 10 because of heavy rain coinciding with a high tide of 2.8m that temporarily overwhelmed the adjacent canal and surrounding roadside drains.
According to Singapore’s third national climate change study (V3), climate change is expected to bring heavier, more intense and frequent storms. This could lead to more flash flooding.
In the low-carbon emission scenario, the rainy season between November and January is expected to get wetter by up to 58 per cent, said the study, which was released in 2023.
Climate change is also expected to cause land ice at the poles to melt, causing sea levels to rise. Higher sea levels, when coupled with high tides, could cause coastal flooding to increase.
The V3 study had shown that by 2100, mean sea levels could rise by 23cm in the best possible climate scenario, or by 1.15m in the worst-case scenario. - The Straits Times/ANN
