Thanksgiving forecast: Light mountain snow possible but inversion likely to linger in Utah

SALT LAKE CITY — It appears that weather won't be an issue for travelers heading in, out and around Utah this Thanksgiving — aside from a weak storm system that could provide a few inches of snow in the northern Utah mountains Wednesday.

That's because high-pressure systems are expected to continue to dominate Utah's weather patterns. This means inversion conditions will likely continue through the week unless the storm system is strong enough to clear out some of the gunky air built up across the Wasatch Front.

A more active pattern is possible next week. Here's a look at what Utahns can expect leading up to Thanksgiving and the long holiday weekend.

The inversion continues

Utah's weather patterns stabilized last week after weeks of storm patterns that produced several feet of snow in Utah's mountains. Alex DeSmet, a meteorologist with the National Weather Service, explained that the active pattern shifted to the East, where, most notably, western New York has been hit hard with lake-effect snow.

"While that transition took place, that meant quieter weather for the West," he said, noting that a series of high-pressure systems started building up over the western United States last week while the low-pressure systems moved to the eastern U.S. "During our active period earlier this month, it was the opposite. So it was our turn for the quieter weather with high pressure."

Unfortunately, the high-pressure system mixed with colder air sparked the return of Utah's temperature inversions, resulting in worsening air quality. The Utah Division of Air Quality forecast calls for moderate air quality conditions across the Wasatch Front on Monday. It's expected to remain that way through at least Wednesday, even reaching levels that are unhealthy for sensitive groups Tuesday and Wednesday in Salt Lake County.

The Utah Division of Human Resource Management tweeted that state employees that can work remotely will work from home this week because of the mandatory action in the air quality forecast.

Small storm arrives before Thanksgiving

The ongoing high-pressure pattern is expected to continue this week; however, a small storm, which is expected to reach northern Utah on Wednesday morning, could offer some relief.

The computer models that the National Weather Service uses for its forecasts seemed to indicate that the storm system would produce nothing in terms of snow accumulations. Those models now indicate there is a growing possibility for a few inches of mountain snow in northern Utah, DeSmet said.

"The potential forecast outcomes range from dry conditions to very light snow, mostly in the mountains," he said. "There's also a very low chance of a brief period of light snow in our northern valleys on Wednesday morning, as well. But right now, even the worst case for valleys looks like a dusting with a couple of inches at most in the mountains in the high-end scenario. The low-end scenario is still nothing — and both are still in play at this point."

Tuesday and Wednesday are, of course, major travel days ahead of Thanksgiving.

KSL meteorologist Matt Johnson said the system will produce some snow but mostly rain in the Pacific Northwest on Tuesday. It's forecast to impact other parts of the Rocky Mountain region on Wednesday. However, the models indicate that the storm will likely only provide a dusting outside of Utah, too.

"This is really not putting down too much — not a lot of moisture with it," he said.

What's also unclear is how strong the storm system is in terms of breaking up the poor air quality along the Wasatch Front. DeSmet said there is "some potential" to weaken the inversion patterns, but it's not clear if it will remove it entirely. What's more likely is that there will still be some haze after the system passes, which will continue to build through the end of the week and into early next week.

A return to stormy weather soon?

Utah's weather patterns may soon shift again, though. The weather service's Climate Prediction Center on Sunday issued a long-range forecast, which places all of Utah within a 66-75% probability for near-normal to above-normal precipitation on the final few days of November.

It's difficult to predict what the precipitation will look like if a storm materializes because that's still a little more than a week away. That said, DeSmet notes that there are computer "indications" that storm-producing low-pressure systems will return to the Intermountain region on the final few days of November with potentially more storms to close out the week.

"The details are still a bit murky but what we can say is the odds are favoring a return to a more active pattern, particularly from (Nov. 29) to beyond next week," he said. "We'll have more details once we get closer."

Full seven-day forecasts for areas across Utah can be found online at the KSL Weather Center.

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