Early forecasts are providing hints at how the 2024-25 winter season may shake out in Colorado. 

This week, several ski areas announced opening dates, including Keystone Resort, Vail Mountain and Steamboat Resort.

While nothing about the upcoming season is certain, confidence is building for the return of La Nina, the atmospheric pattern defined by wet, cold weather in the north and drier, warmer weather in the south. While last winter was dominated by the opposite pattern, El Nino, the three winters before that were all La Nina years. 

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La Nina occurs when surface temperatures in the equatorial Pacific Ocean fall below average, pushing the jet stream north. 

According to Colorado Climate Center climatologist Peter Goble, this can make for a drier, warmer fall and a slower start to the winter season. But once temperatures begin to drop from December through February, the pattern can bring above-average precipitation that, coupled with the cold, makes for better snow conditions.

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If such conditions occur, it’ll likely be in the northern mountain areas like Steamboat Springs. Goble said the correlation between La Nina and strong winter snow isn’t perfect, adding that in some La Nina years snowfall was normal or below average. 

“I would say it is kind of like having a couple extra aces in your deck playing a game of poker,” Goble said. “The odds are you’re going to draw a better hand, but you could still draw a poor hand.”

Statewide snowpack over the past four years has been a mixed bag, according to data from the Natural Resources Conservation Center. 

Snowpack during the 2023-24 season — an El Nino year — lagged below normal for practically all of November through January. Levels did begin to climb in February before reaching above normal from mid-March through mid-April. Snowpack remained near or slightly above normal through May and June. 

The 2022-23 season — a La Nina year — was a blockbuster by comparison. While snowpack took about two weeks longer to build than in 2023-24, levels surged in early November and remained well above normal from January to May.

The two years prior to that — also La Nina seasons — were mostly below normal, save for a big snowpack bump in January in 2021-22. 

Looking back to earlier La Nina years, Goble said there have been seasons when even the northern Rockies did not see above-average precipitation, such as in 2012 and 2018.

A forecast by the Climate Prediction Center issued Aug. 15 shows a slight chance for below-normal precipitation and near-normal temperatures in Colorado’s High Country for the months of December, January and February. 

While Bogle said those predictions don’t necessarily align with what is expected from La Nina, the forecast does make sense when looking nationally. 

In the Pacific Northwest, where La Nina’s effects are most pronounced, there is anywhere from a 33% to 50% chance for below-normal temperatures and as much as a 50% to 60% chance for above-normal precipitation. By contrast, parts of the southern U.S. have a 50% to 60% chance of below-normal precipitation and above-average temperatures. 

“In a changing climate where we are trending warmer, we are seeing winters that are warmer than historical avengers,” Bogle said. “That said, Colorado builds our snowpack at a higher elevation than most ski areas in our country. … The ‘champagne powder’ isn’t going away any time soon.”

When it comes to northern Colorado in particular, Bogle said he anticipates good winter conditions this coming season, despite early predictions that those areas could see less precipitation. 

“For areas like Steamboat and Winter Park, it would surprise me to see below-average precipitation for La Nina,” Bogle said. “Those mid-winter snowstorms are likely to be champagne powder, so perhaps a bit of cautious optimism there.”

In an Aug. 13 blog post on OpenSnow.com, meteorologist Alan Smith wrote that the “relative strength of a La Niña is also an important factor when it comes to prevailing weather patterns,” adding, “So far, La Niña conditions have been slower to emerge than previously forecast earlier this summer.”

Models from the National Oceanic and Atmospheric Administration currently show a 74% chance of La Nina conditions prevailing through the winter of 2024-2025, Smith wrote.

“Since 1990, there have been six winters in which weak La Niña conditions were present,” Smith wrote. “The last weak La Nina occurred just two years ago in 2022-2023 (which, by the way, was a huge winter for much of the West).”

Whether La Nina transitions back to El Nino, as it did last season, is uncertain, Bogle said. 

“The last couple times that La Nina has developed it has stuck around for two or three years, but that’s not necessarily what we expect every time,” he said. “A lot of the time La Nina comes through and it is just a one-year event.”