Wyoming's Wild Weather: Snow And Pushing 100 Degrees This Weekend

Friday is the first day of summer, and people in Wheatland, Wyoming, will feel it with temperatures forecast by the National Weather Service to push 100 degrees.

Other high-elevation parts of the state can expect snow and below-freezing temperatures.  

Wyoming’s about to reach the crest of a weeklong roller coaster of schizophrenic weather that’ll impact the entire United States. Air from Alaska will make the Western U.S. unseasonably cold, while heat records could be broken in the eastern U.S.

The National Weather Service (NWS) has issued a Winter Storm Watch for Glacier National Park in northern Montana. It anticipates up to a foot of snow at elevations above 6,000 feet and as much as 4 inches at lower spots.

No watches have been issued for Yellowstone National Park or the Beartooth Highway, but freezing temperatures and snow are likely in Wyoming's high-elevation areas between Saturday and Sunday. 

The rest of Wyoming will get much colder and damper to celebrate the first days of summer, but not before a broiling start to the season Friday.

In eastern Wyoming, the NWS says to expect highs in the 80s to mid-90s Friday and Saturday, with Wheatland and some areas east of the Interstate 25 corridor hitting 100-105. It’s expected to cool off after that.

Even Cowboy State Daily meteorologist Don Day had to say, “Wow," when looking at what's coming. 

“The first day of summer is Friday, and we might only have highs in the upper 50s by Sunday and lows in the upper 30s by Sunday," he said. "I’ve seen this before around the first day of summer, but it doesn’t happen very often. 

“It’s wild, and either way, everyone’s going to be mad at me.”

Alaska Air

The source of this summer snow is a surge of cold, moist air descending from the Gulf of Alaska. It’s been swirling over the Pacific Ocean near British Columbia while Alaska has undergone an unprecedented heat wave.

“It’s been really hot in Alaska,” Day said. “They’ve reached the 90s up there. Meanwhile, this cold, moist storm has been sitting just south of Alaska for several days. As it gets unstuck, it will move south across Montana and Wyoming.”

While this isn’t a winter storm, it’ll be cold and wet enough to dump several inches of snow in northern Montana. 

Day said this system also will be strong enough to bring snow to the highest points of northwest Wyoming and unseasonably cool temperatures to the rest of the state once it gets here.

“Will it snow in northwest Wyoming? I think it will,” he said. “I won’t guess any amounts, but I think Yellowstone, the Northern Bighorns, and the highest points of the Wind River Mountains have a chance to see some snowflakes.”

It won’t snow on the first day of summer, at least not in Wyoming. The system won’t reach Wyoming until Saturday night. Until then, it’s fun times in the scorching summer.

The Blowtorch

The next few days will be scorching over Wyoming. 

Taylor Wittman with the NWS office in Riverton said Wyomingites can expect “unseasonably warm” temperatures before the cold weather system moves in.

“This high-pressure system will peak on Thursday, but Friday and Saturday will still be unseasonably warm,” he said. “We’re looking at the mid- to upper 90s across Wyoming today.”

Wittman said the record high temperature for Casper on June 19 is 99 degrees in 1989. Thursday’s expected high in Casper was 94 degrees, so not quite record-breaking but still within the hottest recorded temperatures for June 19.

“Riverton had a tie for June 19 at 95 degrees,” Wittman said. “Cody also tied its record-high at 90 degrees. Lander’s high on Thursday was 91, which doesn’t break its record of 97 in 1940, but that’s still within the top five recorded temperatures for this date.”

The first winds of change will be literal winds. 

Day anticipates that Friday and Saturday will be excessively windy, making the next few days feel like “a blowtorch” outside.

“It’s going to get pretty windy in parts of Wyoming ahead of the front on Friday and Saturday,” he said. “First, it's going to be like a blowtorch —hot and windy — and then it's going to be cold and windy.”

That blowtorch metaphor could be ominously appropriate. Day cautioned that high temperatures and strong winds are the conditions for enhanced fire danger.

“When you get these types of patterns, when humidities get really low and temperatures get hot, we’re put in a position where fire danger goes up, especially in eastern and northeastern Wyoming,” he said. “Folks need to be aware that there’ll be some elevated fire risk over the next two days.”

Then, it gets cold and wet.

Dampening The Summer Spirit

When the next cold weather system arrives, most of Wyoming will experience a 20-to-30-degree temperature drop. 

It will begin in western Wyoming on Saturday night, slowly creep over the Continental Divide, and descend upon the rest of the state by Monday.

“Sunday will be the coolest day for most of the state,” Wittman said. “Jackson, Big Piney, Pinedale, and Yellowstone are looking at lows in the mid to upper 20s on Saturday and Sunday nights.”

Day described Sunday and Monday as “cool and unsettled” for most of Wyoming.

“The eastern side of the state is not going to start seeing the front until Sunday afternoon or evening,” he said. “By Monday, the whole state will see temperatures 20 to 30 degrees colder than they are now. Highs in the upper 50s and overnight lows in the 30s.”

The irony is that the exact opposite will be happening across the eastern half of the United States. While it’ll be unseasonably cool in Western states, eastern states will experience a potentially record-breaking heat wave.

That’s why Day said it’ll be important for Wyomingites to seek out local forecasts over the next week. The eastern heatwave will eclipse any snow in Glacier or Yellowstone National Parks.

“You're going to hear about the heat wave in the east on the news,” he said. “They probably won’t mention the snow in Glacier or the much colder weather coming into the West, because that's how the national media works.”

Dramatic Drought Improvement

The good news about this surge of unseasonably cool temperatures is that it increases the chances of moisture in areas where it’s needed most. 

Day said there’s been “a huge turnaround” in eastern Wyoming’s drought situation.

“In the last two months, there's been a two to three class improvement on the Wyoming Drought Monitor,” he said. “That means places classified as experiencing Extreme or Exceptional drought are now classified as Moderate or Abnormally Dry. 

“That’s a dramatic change and a lot of improvement in that pocket of dryness in eastern Wyoming.”

But while eastern Wyoming’s getting wetter, western Wyoming is losing moisture. 

Harkening back to his warning about increased fire danger, Day said people in western Wyoming should be on their guard going forward.

“Overall, this system will bring precipitation to Wyoming, especially to the northwest parts of the state,” he said. “Next week, we see some good chances of showers and thunderstorms, especially in the east.”

Summer Days

Anyone worried about the incoming cold won’t have to endure it for too long. Or, at least, summer temperatures should be back in full swing by the beginning of July.

“Our summer pattern has been delayed about three weeks,” Day said. “I would say this incoming system is more of a late May pattern. Once we get through the next week, everything should start to stabilize.”

Wittman said the three-to-four-week outlook for Wyoming’s weather shows warmer-than-average temperatures across Wyoming between June 28 and July 11, with normal to slightly below-average precipitation over the same period.

“That doesn't mean you can't get a system that brings cold weather, like we're going to see this weekend,” he said. “These are super long-range models, but overall, we’re trending towards above-average temperatures for the rest of the summer.”

In the meantime, anyone planning to spend the first day of summer driving along the Beartooth Highway or strolling the boardwalk at Old Faithful shouldn’t be surprised to encounter a summer snow shower.

“If you’re planning a trip to Yellowstone this week, dress warmly,” Day said.

Andrew Rossi can be reached at arossi@cowboystatedaily.com.