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Textbooks said a storm couldn't form here. One did anyway.

In late December 2001, an almost impossible storm formed just north of the equator in the South China Sea, closer to that line than any tropical cyclone ever recorded. Vamei grew out of a small vortex that forms every winter off the northwest coast of Borneo, this time stretched slowly southward by crossing monsoon winds until the usually negligible Coriolis effect near the equator was enough to spin it into a genuine cyclone. It strengthened fast, developed a compact eye, and made landfall in extreme southeastern Malaysia within a day of being named, before crossing the peninsula and weakening over Sumatra. Remarkably, its remnants survived the crossing and reorganized days later in the Bay of Bengal, briefly becoming a tropical storm again before wind shear finally tore it apart on New Year's Day.

How strong Vamei actually got is still argued over: Japan's weather agency called it a modest tropical storm, while the US Navy's Joint Typhoon Warning Center, going by ship reports from inside the eye recording much higher winds, rated it a full typhoon. Researchers who later studied the event estimated that the unusual combination of a persistent wind surge, a slow-moving vortex, and a narrow stretch of sea between Borneo and Singapore needed for such a storm to form happens only once every one to four centuries. That rarity made Vamei's existence a genuine surprise to meteorologists who had long assumed equatorial waters were simply too calm, rotationally speaking, for cyclones to spin up at all.

On the ground, the storm caught many Malaysians off guard despite official warnings, bringing heavy rain, flooding and a deadly landslide near Gunung Pulai that killed five people and destroyed several homes. Thousands were evacuated into shelters across Johor and Pahang, crops and infrastructure were damaged, and the government handed out emergency payments to affected families. Neighboring Singapore saw flight disruptions and fallen trees from the storm's outer rains. Because of the damage and its historic significance, the name Vamei was retired in 2004, becoming the first name ever retired from the Japan Meteorological Agency's typhoon-naming list.

Vamei formed at 1.4 degrees north — closer to the equator than any tropical cyclone ever recorded — and after dissipating over Sumatra its remnants reorganized in the North Indian Ocean before finally fading on New Year's Day.

Read the whole of Tropical Storm Vamei on Wikipedia

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