How long will Tri-Cities gray skies last? Too long

An air stagnation advisory for the Tri-Cities has been extended for a second time.

The National Weather Service says stagnant air conditions are expected to last until at least Thursday morning.

That means more gray skies and freezing fog in the mornings and evenings.

An upper level ridge has settled over the Pacific Northwest limiting air movement in the Tri-Cities.

Air quality could deteriorate with no breeze to disperse pollutants, but Saturday the air quality in the Tri-City area remained rated as “good” by the Benton Clean Air Agency.

Lows are expected to remain in the 20s most nights in the Tri-Cities through Thursday night, with the possible exception of Saturday night. Then the temperature may reach just below freezing.

Highs are forecast for the low to mid 30s through Friday.

This story was originally published December 9, 2017 at 12:33 PM with the headline "How long will Tri-Cities gray skies last? Too long."