The Impossible Typhoon

NASA Image

Tropical cyclones form when masses of thunderstorms stay organized long enough for the Coriolis effect to give them a little kick and start them spinning. At the equator, the Earth’s rotational effect is zero. Theoretically, it is impossible for cyclones to form near the equator. So, the belt about 300 miles either side of the Equator has been believed to be tropical cylone free.

Weather forecasters and scientists were amazed on December 27, 2001 when Typhoon Vamei formed near Singapore. The winter season features a persistent low pressure system near Borneo. Cold air intrusions can dive southward off the Asian continent. This cold surge wrapped around the vortex and spun up a tropical depression on the evening of the 26th. It was the first time that a tropical cyclone had formed so close to the equator. A few hours later, it was designated Tropical Storm Vamei when it was 40 miles northeast of Singapore.

A U.S. Navy ship reported wind of 85 mph as it plunged into the 24 mile wide eye. A second ship reported 120 mph winds in the southern eyewall. Based on these reports, the system was upgraded to Typhoon Vamei. Vamei made landfall along the Malaysian coast around 0830 GMT on the 27th.

A post storm analysis revealed that the South China Sea is one of the few places that such a surprise trpical cyclone could occur. Researchers estimate that such an occurrence is still very rare, happening only once in every four hundred years.

The name Vamei comes from the nation Macau. It means a songbird with white feathers. The name was retired after its only use.

– Bill Murray
bill.murray@theweathercompany.com
Follow my weather history tweets on Twitter. I am wxhistorian.

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