The Utah Division of Air Quality, meanwhile, raised the dreaded "Red" banners for Salt Lake, Davis, Cache, Weber and Utah counties on Tuesday and planned to leave them in place for Wednesday and into the weekend. Utahns could blame both automotive and industrial pollution and the return of inversions trapping the dirty air in the state's urban valleys.
How long will the latest inversions last? The National Weather Service put it this way: "Strong and persistent valley inversions across the forecast area through the foreseeable future."
"Red" air quality alerts bring with them warnings for the elderly, young children and those with compromised heart and lung health to avoid extended outdoor activity. Motorists are urged to park their cars in favor of mass transit, or work from home if possible, and wood-burning stove use is discouraged, and in some cases banned.
Salt Lake City's temperature forecast looked like this: Tuesday an 18-degree high, followed by an overnight low of 9, and a daytime reading Wednesday of 19 degrees; Ogden followed with 14, 7 and 18 degrees, respectively; Provo 16, 5 and 20; Logan 12, 1 and 12; Wendover 15, 5 and 13; Duchesne 6, -12 and 13; Cedar City 16, -2 and 27; St. George 38, 19 and 44; and Moab 9, -5 and 15 degrees.
The Utah Avalanche Center rated Ogden and Provo area mountains at "considerable" risk for dangerous backcountry snow slides to begin Tuesday, but later changed the risk rating for all of the state's mountains to "moderate" going into Wednesday.