SINGAPORE - The hail from Tuesday's (Jan 30) storm in northern Singapore was not linked to the monsoon season, said an expert from Nanyang Technological University (NTU).
Rather, it was caused by the chance lining up of all the right conditions, said Professor Benjamin Horton, principal investigator at NTU's Earth Observatory of Singapore.
He noted that hail fell in Singapore in March 2008, September 2009, June 2013 and October 2014.
"Each time, it was associated with heavy thunderstorms, and the timing indicates no link to the monsoon season, which commonly occurs from November to January."
In the latest case, he said "the upper atmospheric conditions of the previous few days, to weeks, allowed the particular thunderstorm cloud to form hailstones".
At least five hailstones the size of five-cent and 10-cent coins rained down onto the balcony floor of the condominium home of Mr Lee M. L., 47, in Yishun.
The morning after the heavy rain, joggers and passers-by were surprised to see several fallen trees in Yishun Park. Photos sent to The Straits Times show at least four such trees blocking pathways in the park.
Ms Seri Dewi Sangha, 31, usually cuts through the park on her way to work but was forced to take a detour.
"Each time I changed path, the next path was blocked. In the end, I climbed over one of the trees," said the radiologist at Khoo Teck Puat Hospital.
"The wind was very strong and everything was being blown horizontally," she added.
In a video sent by Yishun resident Lim Chee Kiang, several trees were completely uprooted by the evening storm. The 19-year-old was making a delivery for UberEats when he encountered several blocked pathways in the park.
On Wednesday evening, The Straits Times spotted a carpark sign smashed by a fallen tree in Yishun Street 72. And workers from Toh Chin Leong Construction were seen clearing damaged tree branches between Blocks 733 and 734, Yishun Ave 5, at around 5pm.
Its driver Tagebahader Ramkewal said his firm handled more than 100 cases of trees damaged in the storm, around three times more than average.
"We're almost done now, and we won't be working till midnight tonight," said the 53-year-old. But on looking up at the darkening sky, he added grimly: "I hope it doesn't happen again."
Ms Shania Poh, 20, who lives in Block 734, Yishun Ave 5, said two flower pots outside her flat fell and broke during the storm. "A lot of water also came into our home," added the polytechnic student.
Nee Soon GRC MP K. Shanmugam told The Straits Times on Wednesday that properties were damaged and trees uprooted by the previous day's exceptionally heavy rain.
Mr Shanmugam, the Law and Home Affairs Minister, said his team's MP Faishal Ibrahim went round Nee Soon on Tuesday to assess the situation and met residents. Fellow MPs Lee Bee Wah and Louis Ng also helped to coordinate responses to the situation.
"Operations to clear the debris are progressing and normalcy is returning," he added.
Mr Shanmugam also said the stormy weather temporarily disrupted a trade fair in Chong Pang.
"Electricity for the lights was temporarily shut down for safety reasons. The trade fair has resumed operations, while some repairs are continuing," he added.
