A "whirlwind" in Tuas captured on video that made the rounds online yesterday is a landspout, the first such reported occurrence in Singapore, said the weatherman.

The National Environment Agency's Meteorological Service Singapore (MSS) said the rotating column of wind was caused by the development of an intense thunderstorm under unstable atmospheric conditions.

A thunderstorm had developed over the waters off Tuas at 10.30am yesterday, subsequently moving inland at 11am.

"The moist air feeding into the intensifying storm resulted in a rotating column of winds over Gul Way around the Tuas area," said MSS.

A landspout is similar to a waterspout that develops over a water body, it said. A landspout typically has a lifespan of several minutes and weakens quickly when the thunderstorm matures or dissipates.

Such landspouts are uncommon here, said Dr Winston Chow, a Singapore Management University associate professor who researches the relationship between urban spaces and the climate.

Dr Matthias Roth, a professor of urban climatology at the National University of Singapore, added that the landspout would have reached from the surface to the base of the clouds above.

Both experts assured that landspouts are usually of low safety risk. However, injuries may result when items that are not properly secured get dislodged.

"Landspouts that can cause damage are thankfully relatively infrequent over land. They are usually more common over water as waterspouts," said Dr Chow.

The Straits Times understands that there were no reported injuries linked to yesterday's landspout.