A blast of winter will drop several inches of snow…

This week’s latest weather system will cut diagonally across Wyoming with a blast of wintry weather. And this time there will be enough cold and snow.

The National Weather Service has already issued a winter weather advisory and warning for most of western and central Wyoming beginning Monday night through Wednesday morning. A slow-moving system will move from the southwest to the northeast of the Cowboy State, bringing the season’s first heavy snow to the plains.

“This system is like a slot machine where you get three sevens,” Cowboy State Daily meteorologist Don Day said. “It’s not a storm, but a combination of events where moisture and cold temperatures will be in the right place at the right time in those regions. So it’s a confluence of events working together.”

Diagonal stripe

While the newest weather system will affect Wyoming as a whole, its biggest impact will be on the “band” it creates as it moves across the Cowboy State. The system will move into the southwest Monday night and move across central Wyoming to the northeast Tuesday and Wednesday.

“It’s not a perfect diagonal, but it’s pretty close,” Day said. “If the line were built, it would run from Salt Lake City to Evanston, Green River and Rock Springs, and then go up through Lander and Riverton.

“Then it will move through Casper, to Gillette, and then to Rapid City. This line is the axis where there will be the strongest humidity.”

The heaviest impact could be 36 to 6 inches of snow in lower areas along the band. And this time, Day said there will be enough snow to stick.

“It’s going to be mostly snow, so it’s going to be the first significant snow on the plains,” he said. “What will happen is the first two inches will melt, but after that it will set pretty well. I expect a lot of areas to see it stick, not just the grassy areas, but the pavement as well.”

There will be some bumps along the edges of the “strip,” but the rest of Wyoming won’t see as much snow.

“That line is the axis where the heaviest moisture will be,” Day said. “About 75 miles on either side of that line will be the part of the state that will be hit the hardest. The southeast and northwest corners will have an impact, but it won’t be as big as those areas on the line.”

The measured snow on the plains means that there will also be significant amounts of snow in the mountains. The Unita, Bighorn and Wind River ranges could see up to a foot of snow through this system, and Mt Casper will likely be blanketed in white by the end of the week.

Cold entrance

The input system is a part weather roller coaster in Wyoming over the past few weeks, Day said. Short wet cold spells were replaced by “bounces” of warm and dry days that are more like the last days of summer than the first days of autumn.

Day said there will be another bounce after the inbound system passes. However, Wyoming’s warmer days will decrease, especially as the days get shorter.

“We will see more funnel systems in the first weeks of November,” he said. “The rebounds in warm temperatures won’t be as fun as they have been lately. Following this system, other funnel systems will appear. It’s the start of a cooler trend that has more legs.”

Day took the opportunity to remind Wyoming residents that daylight saving time is almost over. Clocks will go back one hour at 2 a.m. on Sunday.

This will add an hour of daylight to the morning. It also means sunset will be even earlier, so everyone should anticipate early evenings.

From Sunday, March 9, 2025, the transition to summer time will begin again.

“We’re at a point in the calendar where it’s just harder to get warm weather,” Day said.

Where and what to expect

When the next winter weather system arrives late Monday night, Day said Wyoming communities in the strip should expect to wake up to a white morning and potentially dangerous driving.

“If I were to name cities and towns, the hardest would be Evanston, Green River, Rock Springs, Lander, Riverton, Casper, Douglas, Buffalo, Gillette, Newcastle and Sundance,” he said. “These are the places that will have the biggest impact.”

This forecast means sections of Interstates 80, 90 and most of I-25 could be slippery from melting snow. Southeast Wyoming will not be affected by the system, but Day warned residents of Cheyenne and Laramie to use caution while commuting on I-80.

“There’s definitely going to be some fallout in Cheyenne and Laramie,” he said. “Between Laramie and Cheyenne, you almost reach 8,000 feet on I-80. And then between Rawlins and Laramie, you’re just under 9,000 feet in some places. I think this catches a lot of out-of-state travelers off guard. It doesn’t feel like you’re on a mountain pass, but you are.”

The rest of Wyoming can expect several inches of snow, gusty winds and plummeting temperatures. High temperatures will be in the 20s and 30s, and a return to the 70s over the weekend is unlikely.

Day warned Wyoming residents to be cautious over the next few days, especially in the afternoon. That’s when the roads become dangerously slippery, especially at high speeds.

“The time of day is very important,” he said. “Many accidents on icy roads tend to happen in the late afternoon and evening when the sun starts to get lower and wet roads become icy, especially at higher elevations.”

Andrew Rossi can be reached at the address [email protected].