As Wyomingites are getting their skis waxed and snowmobiles tuned up, they turn to longtime Wyoming meteorologist Don Day to guide their winter plans.
And after weeks of geeking out over maps, trends and historical data, Day has come up with his 2024-2025 long-range winter outlook for Wyoming. All those hours of checking and double-checking can be boiled down to two words: colder, snowier.
That’s the short version, explaining that this coming winter will be different from last. While North America endures a El Niño-La Niña whiplash transition phase, the signs strongly suggest that Wyoming has a real winter on the way, Day said.
These are broad statements, and nobody dislikes broad statements more than Day. He’s the first to admit that his outlook isn't perfect, but he has a strong feeling that there will be more winter in Winter 2024-2025.
“When you digest these long-range forecasts, broad statements don't work well for everybody,” said Day, who also is Cowboy State Daily’s meteorologist. “There could be some parts of Wyoming that have a pretty cold, snowy winter, and some parts of Wyoming may be spared from that. But overall, everybody will have more winter this year than last year.”
Fall First
Before Wyoming gets into the worst of the winter season, Day started his outlook with an overview of what fall will feel like in the Cowboy State.
“I don't see anything too earth-shattering in the rest of September, October and November,” he said. “I think it will be a little warmer and probably a bit drier than average. We usually get snow in October, and I definitely expect freezing temperatures by early October, but nothing to rock the boat.”
Day’s fall and winter outlooks are primarily determined by trends that can be observed in the present. But following current trends isn’t a guarantee of what will manifest several months from now.
“We can't get too specific,” he said. “We can just try to hit the trends, but it looks like it’s going to be a nice fall.
Opposite Starts
Day said the setup for Winter 2024-2025 is “much different” from what was happening at this time last year. This season is almost completely opposite from last season, which will profoundly impact Wyoming’s winter.
Two factors matter more than anything else, he said. First, winter starts in a La Niña pattern this year, while it started in an El Niño pattern last year.
“Last winter, the tropical waters of the Pacific Ocean were warm, and that played a big role last winter,” he said. “This winter, we're starting with a La Niña, which is the opposite. The beginning of winter is very different in the Pacific, which is a huge deal.”
Second, wind patterns in the stratosphere are moving in different directions than in 2023. Day said these patterns change every 14 months, but the current pattern should hold steady through Winter 2024-2025.
Day said the La Niña start and the different stratospheric wind patterns are the two “big players” determining what appears in any North America winter forecast. Given that everything this year is an inverse from last year's, making a repeat of last winter is highly unlikely.
“The overall writing message is don't expect this winter to be just like last winter,” he said. “The odds of it being very similar to last year are very low.”
Colder Everywhere
Since the La Niña pattern will stay strong enough to endure into March, Day anticipates that the coldest months of the year in Wyoming — December, January and February — will be colder than average.
“It’s looking like this part of the country will likely have colder than normal temperatures during the heart of winter,” he said. “But that comes with an asterisk in Wyoming because the Continental Divide goes right down the middle of the state.”
Day said the high elevation of the Continental Divide works like a shield, deflecting and redirecting intrusions of air across Wyoming. If Winter 2024-2025 is colder than average, some regions will be colder than others.
“What you'll see a lot of times in the pattern we're expecting is that the coldest parts of Wyoming will be the northern and eastern counties,” he said. “The western and southwest parts of the state will sometimes get shielded from northern intrusions of cold air. I think the coldest, harshest parts of winter will be in central, northern and eastern Wyoming.”
In Winter 2023-2024, the rare manifestation of a Modoki El Niño caused several spells of subzero temperatures that caused tremendous disturbances in Wyoming. Day expects similar, more persistent subzero outbreaks this winter.
“I think the cold will stick longer,” he said. “La Niña winters can cause some pretty good Arctic outbreaks, especially in the beginning. We should expect the winter to have a few cold snaps where we see subzero temperatures, and they're likely to stick around a bit longer.”
Snowier Somewhere
Where there’s cold, there should be snow, and Day thinks there will be more snow in Wyoming this winter.
“There are some pretty good indications that we'll have above-normal snowfall,” he said. “This pattern also lends itself to good mountain snowpack.”
However, it’s regionally dependent. The same wind shielding from the Continental Divide also determines which area of Wyoming gets the most snow, and Day anticipates it’ll be snowier where it's colder.
“The odds are highest that central, northern and eastern Wyoming will get the best snowpack if that happens,” he said. “Last winter, the snow was directed to the south because of El Niño. This winter, it will likely be more directed to the north.”
Resorts like the Sleeping Giant Ski Area near Cody will celebrate this news. Sleeping Giant was forced to cancel its 2023-2024 winter season because of a persistently poor snowpack.
Day offered no guarantees, but anticipates a much better season for Sleeping Giant and other ski resorts in the northern half of Wyoming. Southern Wyoming won’t go without, but probably won’t have the windfall of snowfall it got last season.
“It doesn't mean there'll be a lack of snow in the south,” he said. “It's just that the pattern that made northern Wyoming snowless last year is not there this year. I'm expecting that the northern and northwest mountain ranges and the Northern Plains will do quite well with snow this year.”
The Building Blocks
Day’s long-term seasonal outlooks combine long-range computer modeling, historical data from Wyoming’s past, and several other factors to develop the most Wyoming-accurate forecast possible. But it’s not always perfect, and he’s the first to admit it.
Day released his long-range outlook for Winter 2023-2024 in mid-August last year. In hindsight, he said it was “too soon” to release one and ranked his work as “OK.”
“I broke my own cardinal rule, but I did OK,” he said. “I accurately predicted less snow in the Northern Rockies and the Northern Plains and the good snowfall in the central and southern Rockies. But the forecast was too cold. It ended up being warmer last winter than I thought. I did it way too early last year.”
It’s the double-edged sword of long-range forecasting. Everyone wants a professional assessment of what will happen as soon as possible but get frustrated at the first sign of a deviation.
There are already few long-range forecasts for Wyoming from national agencies, and there is likely to be plenty of meteorological madness altering the impact of Wyoming’s winter between now and then. Day encourages Wyomingites to look local, trust today’s broad statements, and wait for the specifics once the snow starts falling.
“I tell people all the time — all we can do is try to hit what overall trends will be and try our best on the timing,” he said. “The weather is never even in Wyoming. It's never the same for everybody. It’s possible that Evanston and Rock Springs won’t have as much cold and snowy weather as Gillette this winter, but the forecast depends on where you are.”
Overall …
Long-range forecasts should be taken with the grains of salt Wyomingites will soon be spreading on their driveways. Day is confident in his long-range outlook for Winter 2024-2025. It’s not perfect, but it gives Wyomingites an idea of what’s coming.
“Overall, if we were to compare, this winter should be colder and have more snow than last winter,” he said. “Last winter ended up with above-average temperatures with below-average snow in the north and near-average snow in the South. It didn't end up being that bad of a winter, but this winter has the earmarks of being a bit harsher."
Contact Andrew Rossi at arossi@cowboystatedaily.com
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
