Significant winter weather for a watch means 5 or more inches of snow and/or sleet within 12 hours, or 7 inches of snow/sleet within 24 hours, or ice accumulation that could cause damage to trees and powerlines, or life-threatening combinations of snow and/or ice with wind.

A Winter Storm Watch is in place from Saturday evening through Monday morning as a surge of Arctic air moves into the Washington, D.C. region, bringing the threat of heavy snow, dangerous cold and the...