Utah forecast: Below-normal cold to continue as air quality worsens

A high pressure system locking cold air over Utah's urban valleys is predicted to keep overnight temperatures in single digits or below zero in some areas into the coming weekend.

What's more, not only will the morning air be bone-chilling, it will be increasingly dirty as automobile and industrial emissions are trapped by northern Utah's dreaded winter valley air inversions, the National Weather Service warned.

"The steady warming aloft Wednesday and beyond will serve to create rather strong valley inversions, especially throughout central and northern Utah. Steadily building urban haze [will be] a given this week," forecasters stated.

The Utah Division of Air Quality projected "yellow," or moderately compromised breathability Tuesday and Wednesday for Salt Lake, Davis, Utah, Weber, Cache and Uintah counties. Yellow grades bring with them "voluntary action" recommendations for choosing mass transit over car travel and limiting outdoor activities for young children, the elderly and those with compromised lung function.

The NWS also issued a Hazardous Weather Outlook on Tuesday for the eastern third of Utah. Light snowfall was expected overnight in the northern mountains and below-normal temperatures were to continue through the remainder of this week.

Records already have tumbled in significant numbers approaching the mid-week.

Tuesday morning's minus 16 on the Utah Test and Training Range broke a record-low of 4 degrees set in 2005; Brigham City's minus 13 shattered a 1972 mark of minus 2; Kanab's minus 12 was three times colder than its previous record of minus 4 (1947); and Zion National Park's minus 4 blew away a 10-degree mark (1919).

Even the daytime highs set records for cold on Tuesday, with Brigham City and Laketown readings of 11 degrees beating previous marks of 14 and 12, respectively, both set in 1972. Fillmore and the Utah Test and Training Range each hit 13 degrees, beating old records of 16 (2009) and 29 (2005), respectively. Among other communities with record-low maximum temperatures Tuesday were Alpine at 16, bettering a 2009 mark of 19, and Price at 18, nipping the 20 degrees set in 1978.

The Utah Avalanche Center elevated its risk ratings for potentially deadly mountain snowslides to "considerable" throughout the state through Tuesday night.

The Salt Lake and Tooele valleys looked for high temperatures on Wednesday in the mid-20s and overnight lows around 10 degrees, a forecast that echoed the one for Tuesday.

Southern Utah looked for highs in the upper-30s and overnight lows in the 20-degree range, a 5-10 degree improvement from Tuesday's forecast.

For more extensive forecast information, visit the Tribune's weather page at sltrib.com/weather.

remims@sltrib.com

Twitter: @remims