MOSES LAKE — Despite all that bright sun and clear skies, air quality has deteriorated and will remain the same in the next few days.

Grant County, and all of eastern Washington for that matter, is under an air stagnation advisory issued by the National Weather Service. Calm conditions and air stagnation are forecast to last through Monday night.

Joey Clevenger, meteorologist with the National Weather Service in Spokane, said air stagnation is basically trapped air.

“We’ve got a ridge of high pressure over the top of us right now that keeps the weather pattern the way it is,” Clevenger said. “Overnight temperatures get really cold and we get a pretty strong inversion over the area.”

An inversion is a layer of warmer air aloft, over a layer of colder air closer to the surface. When that happens, the air at the surface can’t go anywhere. There’s no wind or moisture to stir up the air and break the inversion.

And any dust, smoke, emissions or other pollutants that are in the air don’t go anywhere either.

“There’s really nothing that’s moving cleaner air into the area,” Clevenger said. “The air quality starts to degrade.”

The forecast shows a series of weak low pressure systems and increasing moisture moving through the area early next week, which should stir up the air and break the inversion. This time of year “moisture” usually means snow, but Clevenger said snow showers, if any, should be confined to the Cascades.