Weather service extends Anchorage dense fog advisory to 2 pm, warns of black ice

National Weather Service forecasters extended Anchorage's dense fog advisory at 11:56 am Tuesday, pushing its expiration from noon to 2 pm. Visibility can drop to a quarter mile or less, and black ice has made roads slick, forecasters said.

The weather service first issued the advisory at 7:02 am. Below-freezing temperatures may also leave frost on bridges and roadways, creating hazardous driving conditions, the advisory said.

"A dense fog advisory means visibilities will frequently be reduced to less than one quarter mile," the weather service said. Drivers should slow down, use headlights and leave plenty of distance ahead of them, the advisory said.

The Anchorage Office of Emergency Management posted its own community alert Tuesday morning, saying a dense fog advisory was in effect for much of the Anchorage bowl and directing residents to the weather service's advisory and forecast.

In a forecast discussion, forecasters said a high-amplitude ridge building over Southcentral Alaska was bringing warmer air aloft and a stout inversion, "a setup ripe for fog development." Observations at Anchorage International Airport recorded fog with temperatures at or below freezing in the early hours.

Fog also settled over the Interior. The weather service's Fairbanks office issued a separate dense fog advisory Tuesday morning for the Fairbanks metro area, Goldstream Valley and Nenana Hills, and Eielson AFB and Salcha, also in effect until 2 pm, with visibility a quarter mile or less at times.

Earlier this month, fog and freezing temperatures raised black ice risk along the Richardson and Parks highways under dense fog advisories for the Copper and Susitna valleys, Alaska News reported Oct. 8.