"Under the Dome." That's not just the title of a horror novel by Stephen King, it's an apt meteorological metaphor for the superheated canopy baking Utah.

Record-setting temperatures could continue along the Wasatch Front through the weekend. The National Weather Service blames it on "strong high pressure aloft" over the western U.S. but centered on Utah.

The western three-quarters of the state were under a "Red Flag" warning through 10 p.m. Saturday. Continued hot temperatures — 10 to 15 degrees above normal for this time of year — coupled with extremely dry forests and high desert ranges and unpredictable winds to make the risk of wildfires extreme.

Strips of southwestern and southcentral Utah, meanwhile, were warned of "excessive heat" through 10 p.m. Friday.

Thursday did not see a record high in Salt Lake City, but it was close: 102 degrees, just 1 degree shy of the capital's 2007 mark. Provo, however, did have a history-making hot day at 104, 2 degrees better than its old 1985 record; and the ski resort community of Alta tied its high for the date at 85 degrees, set in 1985.

The Salt Lake and Tooele valleys looked for highs around 101 on Saturday, down a couple degrees from Friday's forecast (and 1 degree off Salt Lake City's 2002 record of 103). Saturday's heat could challenge the capital's 1976 record of 101, however.

Sunday's high was forecast to be 101, 2 degrees from setting a record.

St. George will sizzle, but still should fall short of records. After Friday's 111-degree forecast, Utah's Dixie looked for 108 on Saturday — 2 and 5 degrees below new marks, respectively.

On Sunday, St. George expects the mercury to retreat a bit, to 105 degrees. That also was not a threat to a 1985 record of 112 degrees.

Some relief from the heat, albeit brief, was expected in both the north and south. Along the Wasatch Front gusty evening thunderstorms and some light rain were possible both Friday night and Saturday afternoon and Sunday evening.

Thunderstorms and scattered showers also were on tap for the region's redrocks and southwestern deserts Friday afternoon and again late Sunday.

That aforementioned "dome" over Utah? Blame that, along with automobile and industrial emissions, for elevated ozone and particulate pollution levels — especially along the state's urban valleys.

The Utah Division of Air Quality graded Salt Lake, Davis, Utah, Weber, Box Elder and Tooele counties as "orange," or threatening to the health of the elderly, young children and those with compromised lung or heart functions. The rest of the state was little better at "yellow," or moderately polluted through the weekend.

The Intermountain Allergy & Asthma website rated mold as "high" and chenopods and plantain "moderate" on its pollen index as of Friday. Other allergens were "low," or did not register.

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

remims@sltrib.com

Twitter: @remims