A bicyclist rides past the White House on Wednesday in Washington. As D.C. prepares for this weekend's snowstorm, a small clipper system pushed through the region Wednesday night causing massive delays and issues on the roads.

WASHINGTON — With heavy snowfall predicted by the weekend from the Appalachians to Philadelphia and maybe farther north, people throughout the region readied themselves for blocked roads, power outages and canceled flights.

The National Weather Service said in a statement Wednesday that 12 to 16 inches of snow could come down between Friday night and Sunday morning around the Interstate 95 corridor. As much as a foot of snow is possible for Philadelphia’s northern suburbs.

Mitchell Gaines of the National Weather Service in Mount Holly, N.J., said people should be prepared for strong winds, heavy, wet snow and power outages.

The National Weather Service’s Weather Prediction Center warns of heavy, “perhaps crippling” snow across the northern mid-Atlantic region, including Baltimore, Washington and Philadelphia, probably beginning Friday.

In the District of Columbia, Mayor Muriel Bowser requested Humvees from the National Guard to reach isolated people and places if necessary.

“If this is a blizzard and we have sustained winds and people lose power, that would be my biggest concern,” Bowser said. “We can move the snow. We will move the snow.”

In the areas where blizzard conditions are possible, the weather service warns that travel will be limited or impossible. The strongest winds and potentially life-threatening conditions are expected Friday night through Saturday night.

The weather service has issued blizzard and winter storm watches for parts of Maryland, Washington, Virginia, West Virginia and Arkansas.