UPDATED 3:20 p.m. A Severe Thunderstorm Warning is in effect for Montgomery County until 4 p.m., according to the National Weather Service:

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR…

WESTERN MONTGOMERY COUNTY IN CENTRAL MARYLAND…CENTRAL LOUDOUN COUNTY IN NORTHERN VIRGINIA…NORTHWESTERN FAIRFAX COUNTY IN NORTHERN VIRGINIA…

* UNTIL 400 PM EDT

* AT 308 PM EDT…A SEVERE THUNDERSTORM WAS DETECTED NEAR OATLANDS…

AND WAS MOVING EAST AT 20 MPH. THIS STORM IS CAPABLE OF PRODUCING HAIL UP TO THE SIZE OF QUARTERS AND DAMAGING WINDS IN EXCESS OF 60 MPH.

* LOCATIONS IMPACTED INCLUDE…

OATLANDS… BROADLANDS… BRAMBLETON… ASHBURN… LANSDOWNE… COUNTRYSIDE… HERNDON…

A Severe Thunderstorm Watch is in effect for most of the D.C. area, including Montgomery County, until 10 p.m.

The National Weather Service issued the Watch this afternoon. Forecasts called for isolated thunderstorms and a 30 percent chance of rain.