All Weather News

Fog and Air Quality Issues in the West

25 Jan 2017, 10:20 am

Several days of fog and air quality issues are possible throughout the Western U.S. this week. With light winds and high humidity, fog will be forming, especially in valleys and low elevations. The fog will likely become dense in the early morning hours with visibility dropping under a .25 mile to near zero at times.

Recent heavy rainfall has added humidity into the atmosphere, along with melting snow. In areas where temperatures have now fallen below freezing, ice may form. Drizzle and mist in the air associated with the fog can cause a thin glaze of ice on untreated roads and surfaces.

Ground fog has also formed in Central California’s San Joaquin Valley and Sacramento Valley. In this area, it is called tule fog. The thick fog forms during California’s rainy season, commonly after the first significant rainfall. With all of the rain and melting snow from the last few weeks, humidity will remain high and fog is likely to develop over the next several days as winds remain light.

An Air Stagnation Advisory has been issued for SW Oregon.  Colder temperatures have now settled into some areas of the west, with warmer air aloft occurring. This is called a temperature inversion, which can help fog form and also trap particles in the lower parts of the atmosphere. Limited air movement may cause pollution and respiratory problems as the air particles stay trapped under the inversion.

Persons who suffer from respiratory problems, especially in heavily populated areas, will be most affected by the air quality issues. Residents with these health problems should remain indoors in climate controlled environments during this weather pattern.

For WeatherNation: Meteorologist Mace Michaels

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