Updated at 6:45 p.m. - Prince George's County has been issued a tornado watch by the National Weather Service.
The watch includes Prince George's County and most of the D.C. region and is in effect until 9 p.m.
According to the Maryland Emergency Management Agency, a tornado watch means "conditions are favorable for a tornado to occur."
If the alert moves to a tornado warning, then "a tornado has been spotted or detected on weather radar and could be coming your way," said MEMA.
In the event of a tornado warning, MEMA advises staying inside and going to a basement or place where there aren't windows; if you're outside, MEMA said to lie flat in a ditch or low area