KUALA LUMPUR, Dec 19 — The heavy downpours that lasted over 24 hours that began late Friday (December 17) night was equal to the average rainfall for a month, which is a one in 100-year weather event.

Environment and Water Ministry (Kasa) secretary-general Datuk Seri Zaini Ujang said the phenomenon occurred due to monsoon flow factors and a low pressure weather system that achieved the level of a tropical depression that formed in the South China Sea that was detected by the Meteorological Department on December 12.

On December 16, the system entered Pahang and moved across the west coast of Peninsular Malaysia, causing a rise in humidity and continuous heavy rain in almost every state in the peninsula.

"It is an exception, because normally during the monsoon season, only states in the East Coast would receive heavy rain but this time, the entire peninsula, especially the central east coast and northern peninsula regions are receiving continuous heavy rain,” he said in a media conference here today.

He cited the high amount of rainfall recorded, with Sentul station being the highest at 363 milimetre (mm), Gombak 247mm, Jinjang 258mm and Sungai Bonus Jalan Tun Razak 273mm.

"The annual rainfall in Kuala Lumpur is 2,400 mm and this means yesterday’s rainfall has exceeded the average rainfall for a month, it is something beyond exepctations and only occurs once every 100 years,” he said.

He said the heavy rains since last Friday are expected to end as the low pressure weather system in the Melaka Straits had moved away from the country and was headed for the Andaman Sea.

"Based on the latest weather model analysis, the rainfall will lessen today, but there are still areas receiving wet weather throughout the day. Based on the analysis, there will be no continuous heavy downpour warning for the Klang Valley this evening,” he added.

The floods that hit the Klang Valley since yesterday following heavy downpours have caused thousands of residents to be evacuated while many motorists were stranded due to congested or flooded roads.

Flooding was also reported to have occurred in Pahang, Melaka, Negeri Sembilan, Terengganu, Kelantan and Perak. — Bernama