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Cyclone unlikely to hit Singapore, experts say

But impact of climate change on other weather patterns merits a closer look

Published on Oct 22, 2013 8:23 AM
 
People watch high tide waves as they stand at the Bay of Bengal coast in Vishakhapatnam, India, on Saturday, Oct 12, 2013. The likes of Cyclone Phailin or Typhoon Wipha are unlikely to ever hit Singapore, experts claim. -- FILE PHOTO: AP

The likes of Cyclone Phailin or Typhoon Wipha are unlikely to ever hit Singapore, experts claim.

However, they say more work needs to be done to find out just how climate change will affect the frequency, intensity and length of tropical cyclones globally.

June to November is generally tropical cyclone season in the north-west Pacific region, said Associate Professor Koh Tieh Yong, a weather researcher at Nanyang Technological University's Earth Observatory of Singapore.

"Sometimes, they can occur in a series, like Phailin, Nari and Wipha," he said.

Tropical cyclones form over large areas of warm ocean, usually more than five degrees north or south of the equator, as air there is pushed about more by the Earth's rotation.

Singapore is therefore too near the Equator for it to stand a high likelihood of being hit.

If they form in the north-west Pacific, they are called typhoons, in the North Atlantic and Central and East Pacific, they are hurricanes. Anywhere else they are referred to as cyclones.

By World Meteorological Organisation classification, a tropical storm becomes a cyclone when the maximum wind speed at its centre goes above 119kmh.

A tropical cyclone has hit Singapore only once. In December 2001, monsoon winds took strongly rotating air from the northern South China Sea southward to the Equator, producing Typhoon Vamei. "Some scientists estimate this kind of rare event does not occur more than once every few hundred years," Prof Koh said.

The National Environment Agency's Meteorological Service Singapore said climate change could lead to an increase in both wind intensity and rainfall rate for tropical cyclones further north in South-east Asia.

Prof Koh said, however, it was "highly unlikely" that tropical cyclones would affect Singapore in the near future.

He added that other weather patterns could be influenced by climate change and these need to be investigated. Though the sea's surface could get warmer, the formation of cyclones also depends on humidity and the difference in wind speeds between the upper and lower atmosphere, he said.

Recently, Singapore has been hit by strong storms. Last Tuesday, a Sumatra squall resulted in flash floods, and a heavy downpour on Sunday saw 77mm of rain causing flooding at Paya Lebar.

With more rain expected in the second half of this month, the total rainfall for October will be above the long-term average, the meteorological service said.

caiwj@sph.com.sg

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