Yesterday's sudden downpour lasted for only one hour, but it was enough to spark flash floods that snarled traffic in the western and southern parts of the island.

Rainwater gushed out from drains, flooding Kampong Bahru Road, Commonwealth Avenue and Cuscaden Road up to knee level, stalling car engines and causing massive traffic jams.

The floods were so deep that only heavy vehicles were able to drive through Cuscaden Road and Kampong Bahru/Lower Delta Road.

Four cars at Cuscaden Road stalled at about 4.40pm, causing a severe bottleneck. Police helped divert traffic till about 5pm, when waters subsided slightly and the roads became passable.

Madam Tan Chwee Imm, 73, was driving along Commonwealth Avenue when she drove straight into the flood. She was taking her son, 42-year-old Dr Chong Y.W., to pick up his car from a service centre in Leng Kee Road.

Said Dr Chong: "The buses overtook us and slowed down in our lane, forcing our car to slow down. I think the water got to the engine."

At Leng Kee Road, 10 brand new cars had to be driven out of a showroom when muddy water gushed in from the drains on the main road.

At Delta Road, Housing Board resident Shirley Wee, 55, said: "I looked out of my window and was shocked that the water had already risen to the level of the seats at a bus stop."

Language trainer Joy Olsen, 54, wrote in to Stomp, The Straits Times' interactive portal, and called it the "worst case of flooding" she has seen from her apartment in Tanjong Pagar.

Said Ms Olsen:"There were floods here in December as well, but this is the worst. Water was just gushing out of the manholes and the cars at Tanjong Pagar railway station were submerged up to their bonnets."

Many Stomp users also reported knee-deep water in the Tanjong Pagar, Telok Blangah and Alexandra Road areas.

A National Environment Agency (NEA) spokesman said yesterday's heavy rain was localised over the city and southern areas.

The highest rainfall was on Sentosa, where by 7pm, 121mm had fallen in just three-and-a-half hours. That was one-third the amount of rain that drenched the island over 24 hours on Dec 16, when Singapore experienced its third-heaviest downpour in 75 years.

But, MaxiCab driver William Ong, 44, saw a silver lining in yesterday's grim clouds.

Bus passengers got down from a public bus and, along with several passers-by, helped to push his vehicle, which had stalled in the middle of Commonwealth Avenue, to the side of the road.

Said Mr Ong: "I'm very touched by their help. This shows that Singaporeans will reach out and help in times of need."