Air over Tri-Cities stagnates. Beware of patches of freezing fog

Drivers will need to watch for icy roads in the morning and night Wednesday as colder temperatures will contribute to freezing fog in places on roadways in the Mid-Columbia, according to the National Weather Service forecast.

Along with fog, stagnant air is forecast for the Tri-Cities area. An air quality advisory is issued through noon on New Year’s Day.

Air quality could worsen as stagnant air allows the buildup of pollutants.

Patchy freezing fog is possible from about 1 to 10 a.m. Wednesday and again Wednesday night, according to the weather forecast.

Overnight lows are forecast to continue to be in the 20s through New Years night.

The lowest temperature this winter has been 20 degrees on Sunday. Tuesday and Wednesday nights the lows should be in the mid 20s, warming to 29 Thursday night.

By Friday lows could be back above freezing.

The coldest day through the end of the week is forecast to be New Year’s Day with a high of 33.

Normal lows for late December are 27 degrees and normal highs are 40 degrees.

A 20% chance of rain and snow is forecast for New Year’s Day. Any precipitation could fall as snow or a mix of snow and rain from 10 a.m. to 1 p.m.

For Thursday night through Saturday a 30% to 50% chance of rain is forecast. By Sunday days should be warmer with a high of 46 forecast.

Mountain travel forecast

Tri-Cities area residents returning from the Seattle area on the weekend after the New Year’s holiday, could face a mix of rain and snow.

Rain and snow are likely at Snoqualmie Pass on Interstate 90 Saturday night through Monday. A wintry mix also is a possibility Saturday, but less likely.

On the Interstate 84 Blue Mountain summit near Meacham, Ore., about 30 miles east of Pendleton, a mix of rain and snow is likely before 10 a.m. Saturday, with a chance of rain and snow continuing through Monday.