Photos: Blanket of fog envelops Anchorage

Drivers were urged to use care on Anchorage-area roads as a dense fog advisory was extended until 5 a.m. Friday in an alert from the National Weather Service in Anchorage.

Visibility was expected to reach one-quarter mile or less at times, leading to more difficult driving conditions, and the possibility of freezing fog could lead to slick roads and the formation of black ice.

"If driving, slow down, use your headlights, and leave plenty of distance ahead of you," the weather service said.