After a day of poor air quality in Northern Utah on Wednesday, the National Weather Service was expecting a mix of light rain and snow in the valley, with “pockets of freezing rain” and patchy valley fog that could complicate Thursday morning’s commute. 

Inversion was only expected to strengthen Thursday into Saturday as high pressure builds, the weather service said.  The organization also predicted icy roads for Interstate 80 west of Tooele and Cache Valley on Thursday morning. 

The weather posed challenges Wednesday, as well, with Salt Lake City International Airport reporting that “about two dozen flights were diverted" in the morning to nearby airports because of poor visibility caused by fog and smog.  The areas most impacted included the airport, I-80, I-215, I-15, and the Legacy Highway in northern Salt Lake through Weber counties, according to the National Weather Service. 

PM 2.5 pollution — fine particulates — rose to the orange (unhealthy for sensitive groups) caution level in Salt Lake County by Wednesday morning; Cache County remained at orange for a second day.  Davis, Utah, Tooele and Weber counties remained at yellow (or moderate) caution levels, according to the Utah Department of Environmental Quality. 

(Courtesy of the National Weather Service) Utah's air quality is not expected to improve over the next few days. 

Those levels are expected to rise over the next several days.  According to the weather service, the inversion will result in “widespread haze” and “deterioration of air quality and some reduction in visibility.”  And there’s “no significant relief in sight during the remainder of the workweek.” 

Forecast daytime highs in the Salt Lake City area are in the upper 30s and low 40s, with overnight lows in the upper 20s and low 30s. 

A storm will bring rain and snow primarily to central and southern Utah through Thursday morning.  Snow accumulation of 4to 8 inches, along with slush, is possible in higher elevations, which may impact travel. 

In northern Utah, there was a 50% chance of snow on Wednesday night, with accumulation of less than half an inch possible.  But that storm is not expected to break up the inversion. 

There’s a better chance that a weekend storm could improve air quality — although it’s not a sure thing.  There’s a chance of snow showers Saturday, mainly after 11 a.m., that continues through Saturday night and Sunday. 

Until then, air quality is expected to deteriorate, with yellow warnings going orange and orange warnings going red. 

Burning solid fuel — using wood-burning fireplaces — is prohibited in counties with yellow or orange warnings.  The DEQ is also advising residents to “reduce vehicle use by consolidating trips.”