Cold front passes through mid-Atlantic region Friday (NOAA)

The National Weather Service writes in its forecast discussion:

cannot rule out a few wet snowflakes Friday night/early Saturday along Allegheny Front

The high spots favored to see some flakes along the Allegheny Front include Dans Mountain west of Cumberland, Md. and around Mt. Storm, Dolly Sods and Mount Porte Crayon in WV.

Precipitation between 5 am and 11 am Saturday colored in green. To the left of the blue line running north-south - which represents freezing at around 5,000 feet, temperatures at high altitudes will be cold enough to support some wet snowflakes. (

Temperatures at all of these locations will struggle to reach 40 degrees Saturday.

Snow in D.C. and nearby suburbs?

Not going to happen. By the time the atmosphere cools sufficiently for precipitation to have a chance to fall as snow (Saturday night), the air will have dried out. I can’t totally rule out some wet flakes mixing in with rain showers in some of the high spots in Loudoun or Frederick county at some point Saturday, but it’s highly unlikely.

Nevertheless, Saturday brings windy, chilly conditions to the entire region. Temperatures may struggle to exceed D.C.’s record low maximum for the date of 56 degrees set in 1899. And if we get some sunshine and mix that with the very cold air aloft, some thundershowers with small hail could develop Saturday afternoon. So a very unsettled, blustery day is on tap.

Big jet stream dip Saturday with upper level low centered over northwest Va. will create instability and cold air aloft (

The cold front coincides with the leading (downstream, eastward) side of the jet stream (offshore by Saturday in the image to the right). And at the base of the jet stream, a bowling ball-like upper level low pressure system(colored in orange and red over NW Va.) rolls by with cold air at high altitudes and rising air (supporting precipitation).

For warm weather fans, the good news is that this crashing jet stream will quickly retreat Sunday into Monday, allowing sunshine and warmer weather to gradually filter back in.