Virginia Gov. Spanberger warns of catastrophic winter storm with dangerous ice, extended power outages. Residents urged to stay off roads.

Leaders in D.C., Maryland and Virginia are bracing for a winter storm that’s slated to begin Saturday and could drop a foot of snow and sleet in the D.C. area.

A state of emergency is often declared ahead of major winter storms. This explainer breaks down what it does, how it helps officials prepare and what it means for the public.