Tri-City weather: air quality worsens, but we might see the sun

After days of gray skies and fog in the Tri-Cities, the National Weather Service is predicting an appearance by the sun in the coming weekend.

In other good news, a new weather system moving in late in the week is less likely to include freezing rain than was predicted earlier.

The weather service is forecasting a 30 percent chance of rain or freezing rain in the Tri-Cities on Friday.

Rain is not expected to fall until after 11 a.m., a change from an early prediction that rain could start before dawn.

Freezing rain is less likely if precipitation falls after the day warms. A high of about 38 degrees is forecast Friday in the Tri-Cities.

The Tri-Cities may get a break from persistent fog and cloudy skies Sunday and Monday. Partly sunny skies are forecast both days.

Air quality in the Tri-Cities was rated as just moderate Wednesday by the Benton Clean Air Agency.

But the new weather system moving into the area Friday is expected to replace the upper level ridge that is preventing air from mixing and clear out pollution near the ground.

The National Weather Service’s air stagnation advisory for the Tri-Cities continues through 10 a.m. Friday.

As long as air quality is rated as moderate rather than good in the Tri-Cities, people with some chronic conditions — such as asthma, lung disease or heart disease — should limit outdoor activities or stick to light outdoor activities, such as walking.

This story was originally published December 13, 2017 at 12:40 PM with the headline "Tri-City weather: air quality worsens, but we might see the sun."