PETALING JAYA - The Meteorological Department will kick off a cloud seeding operation on Monday evening, which is hoped to provide some much needed rainfall over dams in Selangor, Negri Sembilan, Malacca and Johor.
Its national weather centre director Muhammad Helmi Abdullah said the operation would be targeted on rainclouds over or near major dams and water catchment areas.
"Even if the clouds are not directly above the targeted areas, we expect the winds will carry them towards the areas," he told The Star, adding that the operation was expected to take around four hours.
Muhammad Helmi said they had identified suitable conditions for cloud seeding based on Sunday's weather forecast, adding that they had then informed the Royal Malaysian Air Force (TUDM) to be on standby. He added that the department may conduct another round of cloud seeding on Tuesday.
He said optimal conditions for cloud seeding included the need for light and variable winds, which were conducive for the formation of towering cumulus clouds.
"In the past week, weather conditions kept fluctuating and there was a very narrow window of opportunity. The winds were also stronger last week, meaning a low chance of rain clouds forming," he explained.
Muhammad Helmi said the operation would be led by the department's atmospheric science and cloud seeding division, with a TUDM aircraft used to transport four 1,000-litre tanks of water containing 150kg of salt each.
He said that the salt solution would be sprayed at the base of the identified clouds, adding that the salt particles would be carried upwards by thermals, which are upward currents of warm air.
He said this would form water vapour that would grow in size as they moved upwards, until they grew so heavy that they would then fall down as rain.
"Through cloud seeding, we are actually accelerating the process of rainfall production as well as increasing the amount of rainfall. We estimate it will take 15 minutes to half an hour for rain to fall after the solution is sprayed," he said.
Muhammad Helmi expressed confidence that the rain would fall in the targeted areas, but said he was unable to predict how much it would increase water levels in the dams as the amount of rainfall depended on factors influencing each individual cloud.
Since Sunday, over two million people in Petaling Jaya, Putrajaya and Kuala Lumpur are enduring a month-long water rationing exercise, with two days of supply followed by two days of dry taps.
It involves 431,617 households and businesses in the districts of Gombak, Kuala Lumpur, Petaling, Klang, Shah Alam, Kuala Selangor and Hulu Selangor.
According to the authorities, the water levels at the Selangor dam and Klang Gates have been deemed critical at 47.5% and 54% respectively.