The National Weather Service has issued a severe thunderstorm watch for much of the National Capital Region, including McLean, through 10 p.m. Thursday.
Thunderstorms will be capable of producing locally damaging wind gusts and large hail, according to the National Weather Service.
In addition, parts of Fairfax and Prince William counties are under a severe thunderstorm warning through 4:45 p.m.
A severe thunderstorm was detected at 4 p.m. Thursday near Bull Run, about six miles southwest of Centreville, and was moving east at 20 mph. The storm is capable of producing winds in excess of 60 mph, according to the National Weather Service.
"This is a dangerous storm," according to the National Weather Service. "If you are in its path, move indoors to a sturdy building and stay away from windows."
The storm is producing frequent cloud-to-ground lightning. If you can hear thunder, you are close enough to be struck by lightning and should move indoors immediately, the warning states.
McLean has a 70 percent chance of severe thunderstorms through the late afternoon and an 80 percent chance into the night.
Tonight's low is forecast to be 65 degrees. Friday is expected to be partly sunny with a high of 76