Heathrow Airport briefly shut a runway and canceled dozens of flights because of a snowstorm causing widespread travel disruption across Britain.

The London airport's northern runway was closed for 45 minutes and re-opened Friday after being de-iced and cleared of snow. About 180 flights were canceled by midday. Rail traffic was disrupted and roads were forced to close amid plunging temperatures and icy conditions.

Forecasts of inclement weather forced hundreds of schools to shut down.

Weather forecasters predicted around 12 inches (30 centimeters) of snow Friday in some areas. Forecasters say the worst of the snow was expected to the south and west of London, though most of the country would be affected.