The National Weather Service issued a tornado warning for northeastern Surry County until 2:15 p.m. Wednesday.
At 1:49 p.m., a severe thunderstorm capable of producing a tornado was located over Pine Ridge in northern Surry County near Mount Airy, moving east 40 mph, the weather service said.
The weather conditions also could produce quarter-size hail, the weather service said. Radar indicated rotation with the storm.
Flying debris will be dangerous to people caught outdoors without shelter, the weather service said. Mobile homes will be damaged or destroyed.
Damage to roofs, windows and vehicles will occur, the weather service said. Tree damage is likely.
The affected areas include Mount Airy and the communities of Flat Rock, Bottom, Pine Ridge and Toast, the weather service said.
People in the affected areas should move to a basement or an interior room on the lowest floor of a sturdy building and avoid windows, the weather service said.
If people are outdoors, in a mobile home or in a vehicle, they should move to the closest substantial shelter and protect themselves from flying debris, the weather service said.
Heavy rainfall may hide a tornado.
"Do not wait to see or hear the tornado," the weather service said. "Take cover now."