Expect fog on Anchorage roads Monday morning

A layer of dense fog over the Anchorage area early Monday prompted advisories from meteorologists and police, who are asking drivers to slow down during their morning commutes.

The Anchorage Police Department warned of "extreme dense fog" along parts of the Seward Highway just before 5:45 a.m. Monday. Police dispatchers said no accidents had been reported due to the fog as of 6 a.m.

The fog, over Anchorage as well as Eagle River and Turnagain Arm, is expected to persist until 1 p.m. according to a National Weather Service advisory.

But the Anchorage Office of Emergency Management reported the fog would re-emerge Monday night. The office issued a dense fog advisory for the Anchorage Bowl, Eagle River and Turnagain Arm lasting from 9 p.m. Monday to 1 p.m. Tuesday.

Anchorage-based National Weather Service meteorologist Joe Wegman said that there were no indications that fog in particular areas was thicker than others Monday.

"As far was we can tell it's uniformly dense across the Anchorage Bowl right now," Wegman said. "It's expected to linger during the morning and gradually dissipate as we get to 1."

Anchorage's persistent fog over the past few weeks has been the product of a strong thermal inversion, in which warmer air at mountaintop level and above has trapped water vapor at lower altitudes.

"It's very stable and it essentially caps all moisture coming off (Cook) Inlet," Wegman said. "It comes in on extremely light winds — 1 or 2 miles per hour are enough to move it around."

The inversion layer has been gradually cooling, and meteorologists expect it to break up by the end of the week. In the meantime, Wegman recommended that drivers use headlights, leave additional space between vehicles and budget additional travel time to reach their destinations.