Monday’s weather was a radically different experience in Wyoming’s opposite corners.
Cody residents woke up to several inches of snow downtown. The daytime high temperature was 10 degrees with wind chills as low as minus 18.
Meanwhile, Cheyenne residents started their day with some spring in their steps, aided by sunny skies and temperatures pushing 60 by midafternoon.
Northwest Wyoming should stay cold and snowy for the next few days, while Cheyenne will be warmer and sunnier. For Cowboy State Daily meteorologist Don Day, it’s all in a day-to-day’s work while a battle of the winter air masses rages over the state.
“Wyoming’s being affected by two completely separate air masses,” he said. “One’s from Canada and one that's from the Pacific. Where they meet is where you get the action, and that’s how we got those impressive snow totals in northern Wyoming.”
Smothered In Snow
The predictions of an extremely snowy weekend were borne out in the mountains of western Wyoming. The Absaroka, Wind and Teton ranges received between 15 and 36 inches of snow Friday through Sunday, and up to 23 inches was reported in Yellowstone National Park.
“We still have some ongoing light snow in the Cody Foothills that’ll taper off by Monday afternoon,” said meteorologist Richard Lowe with the National Weather Service (NWS) office in Riverton. “The next little system will bring more snow to western Wyoming starting Tuesday afternoon and overnight into Wednesday.”
Over the weekend, a massive cold front from Canada collided with a pocket of moisture from the Pacific Ocean. This caused subzero temperatures and significant snowfall in Cody on Sunday and Monday, which was the most snow the city had seen all season.
Up to 60 inches of snow were reported at the highest points of the Tetons. Official measurements have yet to be taken, but Lowe and Day were sure that several feet of snow had accumulated in the western mountains.
“The Jackson Hole ski area has had 31 inches of snow since Friday,” Day said. “The amounts always vary, but it seems the area between Bondurant and Pinedale above 7,000 feet got the heaviest amount of snow. And we’re getting reports of up to 10 inches in Cody and Powell on Monday.”
Record Highs
The snow story couldn’t be more different in the rest of Wyoming. While Jackson and Cody were being buried in snow, Casper and Rock Springs broke their high-temperature records on Sunday.
“Casper hit 57 on Sunday, breaking its record of 56 set in 1954,” Lowe said. “Rock Springs hit 49, breaking its record of 48 in 2000.”
Lowe said these high temperatures were caused by high winds that swept across Sweetwater and Fremont Counties over the weekend. Those winds mixed with the warmer air aloft and forced it down to the surface.
This disparity isn’t uncommon in Wyoming, even in the depths of winter. Lowe said the record-breaking highs were a direct result of the snowpocalypse in the higher elevations.
“You can have different types of weather for different parts of the state,” he said. “The cold front that came down into the Cody Foothills got trapped in the Bighorn Basin, and anything south got all the winds and the warmer temperatures.”
Some places got the worst of both winter conditions. In South Pass, at least two feet of snow fell over the weekend, along with wind gusts of up to 101 mph.
“It was brutal in South Pass this weekend, and it still is,” Day said. “Those strong jet stream winds were racing from the Pacific right into the state.”
Battle Of The Air Masses
Wyoming sits at the geographic confluence where frigid Arctic air mixes with warm Pacific moisture. Day said this “atmospheric river” determines where winter weather develops, drops, and moves.
“It's a battle of air masses,” he said. “The southern half of Wyoming had this very strong, moist Pacific jet stream wind come in from north of Hawaii, bringing a maritime Pacific air mass into the state. At the same time, this Arctic air mass sitting over Alberta, Saskatchewan, and Montana snuck underneath that Pacific pipeline and tapped into that moisture. That’s how you got that band of snow across northern Wyoming.”
Day likened these interactions to a football game. The subzero surges of January were “setting up the pass” that has and will continue to manifest as waves of snow and subzero temperatures for the next several weeks.
“You run the ball up the middle a few times, then throw it deep, so it's like you're setting up the pass,” he said. “What happens often is when you have a big Arctic outbreak in January, it sets the stage for a powerful Pacific jet stream to form. There will always be a response to these significant shifts in the weather pattern.”
While these air masses mix, they also battle for supremacy. Day said the rest of Wyoming’s winter will be determined by the back and forth between the Arctic air and Pacific moisture, with the weather being determined by which system is strong enough to prevail.
“Over the next five days, it’s going to be very mild in the south and quite cold in the north,” he said. “Next week, Canada wins, so we'll get cold air overspreading the entire state, just not the North. There will always be a wiggle back and forth.”
Wealth Of Winter
If the first three days are any indication, February will be a busy month for Wyoming. The next winter weather systems are already on the horizon.
“The next bigger system moving in from Thursday night into Friday will be a little more potent for the eastern areas,” Lowe said. “We'll start seeing the snow chances increase and make it east of the Continental Divide into the Wind River Basin and as far as I-25.”
Another wave of Pacific moisture will hit the western slopes of Wyoming on Thursday night, bringing more snow to the highest points of the Teton, Absaroka, and Wind River ranges. Day said that wave would “unlock” more Arctic air, lowering temperatures statewide.
“Air coming from north of Hawaii is literally getting shoved into the mountains in little waves, and each of these waves will bring heavy snow and winds with them,” he said. “The wind on South Pass and other parts of the state will be a concern off and on all week, but the wind will be where it's warm.”
The primary takeaway is that there’s plenty of winter weather ahead for Wyoming. That doesn’t mean it’ll be perpetually cold and snowier, which is something Day wants more Wyomingites to remember about their winters.
“We do not live in the part of the world where cold air locks in for the whole winter,” he said. “People tend to remember the extreme cold events or the extreme warm events and then think that a whole winter season is like that. But this back and forth is very typical.”
The back-and-forth of warm and cold periods will continue when Wyoming reaches the second half of February and proceeds into March and April. That stormy pattern means more weather will turn through Wyoming in the weeks and months ahead, bringing more snow, wind, and subzero surges.
“It’s still early February,” Lowe said. “There's plenty of wintry chances in our future.”
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
