Nasty weather in peninsular Malaysia, no thanks to La Nina

Serean Lau The Star 19 Aug 10;

PETALING JAYA: People in the peninsula must brace themselves for some nasty weather that will bring heavy rain, lightning and thunderstorms right up to early next year.

According to a senior officer at the Malaysian Meteorological Department, thunderstorms usually occurred during the inter-monsoon seasons between March and May.

“This year, however, there’s an exceptional occurrence of thunderstorms with the La Nina phenomenon (the occurrence of cooler sea surface temperatures across the equatorial region of the Pacific Ocean).

“Normally, in August, we do not have thunderstorms because we will be getting the south-westerly winds.

“With La Nina, the north-easterly winds are much stronger than the south-westerly winds, which causes heavy rains and thunderstorms.”

He said the thunderstorms would occur when sea breeze and north-easterly winds met.

“If you notice, we get more rain in the afternoon rather than in the morning. This is due to wind patterns,” said the officer, adding that Klang Valley had the highest lightning density followed by southern states.

He said many factors played a role in the formation of lightning but the main aspect was urban heat islands, formed by the modification of the land surface by urban development that used materials that effectively retained heat.

He said urban heat islands could alter weather patterns, including an increase in thunderstorm activity.

A Universiti Putra Malaysia lightning expert said human industrial areas were also prone to increased thunderstorm activity.

“Gases, pollutants and chemicals emitted from factories create a buffer for deep convection. They initiate vertical lifting, resulting in an unstable air mass.

“When a place is filled with factories, there is a higher chance of r lightning.

“These unstable ingredients in the air can speed up storm-cloud creation,” said Dr Mohd Zainal Abidin Ab Kadir, chairman of the university’s Centre of Excellence on Lightning Protection.