Cold front pushes smoke to northern Utah, ushers in coolest temperatures in months

SALT LAKE CITY — Break out the sweaters because a cold front is coming to Utah, signaling an official change of the seasons.

The cold front passing through northern Utah early Thursday is expected to drop high temperatures from the upper 80s and low 90s across the Wasatch Front on Wednesday, to the low 70s and upper 60s on Thursday. It may even provide some high-elevation mountain snow, but most of the precipitation tied to the low-pressure system is expected to pass north of Utah.

"There have been (nearly 100 days) since we've seen temperatures this cool, so we'll definitely be not acclimated to it," said KSL meteorologist Matt Johnson.

However, it will get windy and the skies will become smoky ahead of the cooldown.

Wind and smoke

The cold front is pushing a low-pressure system out of the Pacific Northwest. Johnson explains the jet stream is beginning to move south for the fall and winter, pumping storm systems into the contiguous U.S. again. Most of the precipitation from the incoming storm will likely impact Idaho and Wyoming, but a cold front will sweep through Utah Thursday morning.

Winds from the southwest will pick up on Wednesday. The National Weather Service advises wind gusts up to 55 mph are forecast through Wednesday. The agency issued a series of red-flag warnings over most of the state for Wednesday afternoon and evening because the wind, warm temperatures and low relative humidity make for "critical fire weather conditions" — meaning new fire starts are possible.

With the wind coming from the southwest, Johnson said it will pull smoke from wildfires in southern California such as the fast-growing Bridge and Line fires burning east of Los Angeles.

That will make Wednesday warm, windy and hazy.

Cooler air — and snow?

The cold front will help clear out the smoke coming from the southwest, but Johnson said it will likely bring in smoke from the northwest again — varying in thickness at times.

It will also make temperatures noticeably cooler. For instance, Thursday is forecast to be Salt Lake City's coolest day since June 18, when the high temperature topped out at 69 degrees. The city went through more than 60 days when temperatures exceeded 90 degrees since then, including 19 100-degree days.

Some precipitation is possible in northern Utah, but the brunt of the storm is expected to impact Idaho and Wyoming. Most of the moisture will fall as rain, but snow is anticipated in high-elevation areas north of Utah.

Some of that could drop into Utah, but the odds of any measurable snow aren't likely with this storm system. The weather service projects there's a 12% probability Kings Peak in the Uinta Mountains could get at least 0.1 inches of snow in the next few days, while parts of the Cottonwood Canyons and Raft River Mountains could also see a slight brushing of snow.

"Last week, it was looking like we would get some snow out of this — and we still might — but if we do, it will be in the Uintas and way up there in the Cache Valley mountains," Johnson said. "It has shifted north with rain and snow."

Idaho, Montana, Oregon, Washington and Wyoming are home to most of the severe, extreme and exceptional drought impacting the West right now, according to the U.S. Drought Monitor, so the anticipated precipitation will be beneficial. It's a key reason why 38 active fires have burned more than a combined 685,000 acres of land in those states.

The largest fires among those have been in Oregon and Idaho, which have periodically pushed heavy smoke into Utah in the past few weeks, similar to what is forecast for Thursday.

More to come

More than anything, this cold front is a sign that fall has arrived in Utah. A slight warmup is expected this weekend when high temperatures are set to return to the mid-80s across the Wasatch Front. But another storm is expected early next week, bringing a higher probability of precipitation and a similar drop in temperatures.

It could be when the first snow of the season arrives in Utah. Full seven-day forecasts for areas across Utah can be found online, at the KSL Weather Center.

"It's definitely a signal that the jet stream — as a whole — is migrating south again," Johnson said. "The storm track goes with it, so ... we start getting our storms going again. That will be the case through December and January before it starts making the trek back north."

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