A tornado spins during stormy weather in Mangum, Oklahoma

Swathes of Oklahoma and Arkansas remain under the threat of tornadoes on Tuesday, forecasters have warned, with one confirmed twister already spawning over Tulsa airport.

"A bowing line of thunderstorms with embedded ... vortices will continue to pose a damaging-wind and tornado threat, with isolated large hail, as it crosses the watch area through the morning," the National Weather Service said.

A tornado-watch area extends over eastern central and northeast Oklahoma and northwest Arkansas, with forecasters urging residents to be prepared. It follows days of extreme weather with dozens of the storms touching down.

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