Prince William County and Northern Virginia are under a severe thunderstorm watch until 8 p.m. Tuesday night. 

The National Weather Service forecast calls for "strong thunderstorms and showers that will develop this afternoon along and south of a slow-moving cold front."

NWS said that some storms could become severe and will become capable of producing damaging wind gusts and possibly large hail. 

The weather that's producing the storm heading into Virginia caused what AccuWeather.com is calling a derecho in Chicago. The Weather Channel also called the wind storm a derecho. 

The Washington Post's Capital Weather Gang's Jason Samenow said that he did not believe the storm to be a derecho because it did not meet the criteria.  

"Compared to the June 29 event, steering currents are more sharply pointed towards the southeast, so the region from central Virginia into the Carolinas is probably most threatened by this developing storm complex, which *could* evolve into a derecho-type system," said Samenow in a Capital Weather Gang posting on the developing weather events.

When a derecho hit Northern Virginia on June 29, thousands were without power for several days.