Half a month's rainfall in two hours

85mm of rain recorded between 9.30am and 11.30am, causing flash floods in western and central areas
Isabelle Liew Straits Times 30 Jun 18;

The heavy downpour yesterday morning, which caused flash floods in the central and western parts of Singapore, was equal to half the average rainfall for the entire month of June.

PUB said about 85mm of rainfall was recorded between 9.30am and 11.30am. The average rainfall for June is 130.7mm. Areas which saw flooding included Lorong Kismis in Upper Bukit Timah, Dunearn Road and Bukit Timah.

At 10.11am, PUB tweeted that flash floods had been reported in Dunearn Road, from Yarwood Avenue to Binjai Park, affecting three lanes of the road. About an hour later, it tweeted that the flooding had eased.

Yesterday's floods were the latest in a series over the past month.

On Tuesday, more than a month's rainfall - about 150mm - fell in four hours in Old Toh Tuck Road, causing flash floods in the central and western parts of Singapore.

On May 26, Kramat Lane and Cavenagh Road, along Orchard Road, saw water rising up to mid-tyre level for about 10 minutes.

PUB said the overall rainfall for June is likely to be above average for most of Singapore. It urged people to exercise caution and avoid walking or driving in flooded areas.

Vehicles negotiating a flooded stretch at King Albert Park MRT station in Dunearn Road at 10.45am yesterday. Areas which saw flooding included Lorong Kismis in Upper Bukit Timah, Dunearn Road and Bukit Timah.

Professor Benjamin Horton, chair of the Asian School of the Environment at Nanyang Technological University, said that it was unusual to see such heavy rainfall in June.

June is the onset of the south-west monsoon season, which usually lasts until September and is characterised by relatively drier and warmer weather conditions.

"We are moving into the supposed drier months - in Singapore the wetter months would be February and December - so heavy rainfall is quite unusual in June," said Prof Horton.

He said that while a single event could not be attributed to climate change, one prediction of climate change is heavy precipitation from more moisture in the atmosphere.

The Meteorological Service Singapore said on June 14 that monsoon conditions are expected to extend into September. It said short-duration thundery showers were expected on five to seven days in the second half of June, mostly in the late morning and afternoon.

PUB said it has ongoing drainage upgrading works at the Bukit Timah First Diversion Canal to increase its capacity. "When completed in the first quarter of 2019, flooding risk in the Bukit Timah area would be alleviated," it added. It will protect buildings in the catchment area such as Ngee Ann Polytechnic, Beauty World Plaza, Bukit Timah Shopping Centre and Sime Darby Centre.

Upgrading works for the Stamford Detention Tank and Stamford Diversion Canal are ongoing, and are expected to be completed by the third quarter of this year.

These are two major projects being built to protect Orchard Road, which was hit by a series of flash floods between 2010 and 2012.

The diversion canal will relieve Stamford Canal of a portion of water, while the detention tank will hold water temporarily so less water flows into Stamford Canal during heavy rain.


Morning storm brings flash floods to central Singapore
LOW YOUJIN Today Online 29 Jun 18;

SINGAPORE – Flash floods hit several areas in the Bukit Timah area amid heavy rain on Friday (June 29) morning.

The heavy downpour also triggered high flood risk warnings for various locations in central and western Singapore for a second time this week. The affected areas include Bishan Road, Yio Chu Kang Road, Penjuru Road, Pasir Pang Road and Neo Pee Teck Lane.

National water agency PUB said the rain gauge at Ngee Ann Polytechnic recorded about 85mm of rainfall between 9.30am and 11.30am on Friday, adding: "This is more than half the average rainfall of 130.7mm (about 65%) in the entire month of June."

Singapore is currently in the middle of the South-west Monsoon season. The Meteorological Service Singapore had earlier forecast that the second half of June will be wetter, with overall rainfall for the month to be above average over most parts of Singapore.

On Friday, national water agency PUB first alerted commuters to flash floods in the central part of Singapore around 10.05am.

Lorong Kismis was the first to be hit by the floodwaters, followed by Dunearn Road minutes later. Both roads were completely flooded.

Around 10.38am, PUB reported that all three lanes of Bukit Timah Road were also flooded.

However, the flash floods only lasted for less than half an hour. The high water levels at Lorong Kismis receded around 10.12am, while Dunearn Road saw the waters subsiding around 10.30am.

Traffic at Bukit Timah Road was passable from around 10.45am.

The National Environment Agency had earlier advised Singaporeans to expect moderate to heavy thundery showers over the southern, western and central areas of the island till early afternoon on Friday.

On Tuesday, flash floods were also reported in several locations across Singapore.

Flash floods occurred in three locations in the West — Lorong Kismis, Toh Tuck Avenue, as well as along the Pan-Island Expressway towards Tuas, after the Eng Neo Avenue exit.

In a statement on Tuesday, PUB said Old Toh Tuck Road received about 150mm of rainfall on Tuesday morning, higher than the average rainfall of 130.7mm in the entire month of June.


'Intense rain' caused flash floods in Bukit Timah area: PUB
Channel NewsAsia 29 Jun 18;

SINGAPORE: Intense rain caused flash floods at four locations in central Singapore on Friday morning (Jun 29), national water agency PUB said in a statement.

The flash floods occurred at Lorong Kismis and Bukit Timah Road, as well as Dunearn Road near Watten Estate Road and along Yarwood Avenue to Binjai Park.

The affected stretch of Bukit Timah Road was from Blackmore Drive to Wilby Road.

The PUB said that about 85mm of rainfall was recorded for two hours between 9.30am and 11.30am at the rain gauge at Ngee Ann Polytechnic in Bukit Timah, which is more than half the average rainfall of 130.7mm in the entire month of June.

This comes after more than a month's rain fell in four hours at Old Toh Tuck Road on Tuesday.

Drainage upgrading works at the Bukit Timah First Diversion Canal is ongoing, said PUB. When completed by the first quarter of 2019, flooding risk at the Bukit Timah area would be alleviated.

PUB said its officers were on site to "investigate and render assistance" at the locations. The flash floods subsided by 11.05am, it added.

"We urge the public to exercise caution and avoid stepping into or driving into flooded areas. During heavy rain, the public should stay tuned to radio broadcast and check PUB’s Facebook www.facebook.com/PUBsg or PUB's mobile app MyWaters for flood updates," it said.

Singapore is currently experiencing the southwest monsoon. Compared to the first half of June 2018, the second half of the month is expected to be wetter and overall rainfall for the month is likely to be above average over most parts of Singapore.

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