Initial forecasts provide indications of what the 2024-25 winter season in Colorado might look like.
This week, several ski resorts announced opening datesincluding Keystone Resort, Vail Mountain and Steamboat Resort.
Although nothing is certain about the coming season, confidence is growing in the return of La Niña, the atmospheric pattern characterized by wet, cold weather in the north and drier, warmer weather in the south. While last winter was dominated by the opposite pattern, El Niño, the three winters before that were all La Niña years..
La Niña occurs when surface temperatures in the equatorial Pacific fall below average, pushing the jet stream northward.
According to Peter Goble, a climatologist at the Colorado Climate Center, this can lead to a drier, warmer fall and a slower start to the winter season. However, once temperatures start to drop between December and February, this pattern can bring above-average precipitation, which, when combined with the cold, will create better snow conditions.
If such conditions occur, they will likely be in northern mountainous regions such as Steamboat Springs. He said the relationship between La Niña and heavy winter snowfall is not perfect, adding that in some La Niña years, snowfall has been normal or below average.
“I would say it’s like having a few extra aces in your deck in poker,” he said. “There’s a good chance you’ll get a better hand, but it can still be a bad hand.”
According to data from the Natural Resources Conservation Center, snowpack across the state has been mixed over the past four years.
Snowpack was below normal for virtually the entire period from November to January during the 2023-24 season – an El Niño year. Levels began to rise in February before rising above normal from mid-March to mid-April. Snowpack remained near or slightly above normal in May and June.
The 2022-23 season – a La Niña year – was a blockbuster by comparison. Although snowpack took about two weeks longer to build than in 2023-24, snow depths jumped in early November and remained well above normal from January through May.
The previous two years – also La Niña years – were mostly below normal, except for a large increase in snow cover in January 2021-22.
Looking back at previous La Niña years, Goble said there have been seasons when even the northern Rocky Mountains did not see above-average rainfall, such as 2012 and 2018.
A forecast by the Climate Prediction Center The weather forecast published on August 15 shows that there is a slight chance of below-average precipitation and near-normal temperatures in Colorado’s High Country during the months of December, January and February.
While he said these predictions do not necessarily match expectations for La Niña, at the national level the forecast makes sense.
In the Pacific Northwest, where the effects of La Niña are felt most strongly, the probability of below-average temperatures is between 33 and 50 percent, and the probability of above-average precipitation is even between 50 and 60 percent. In parts of the southern United States, however, the probability of below-average precipitation and above-average temperatures is between 50 and 60 percent.
“In a changing climate where temperatures are getting warmer, we are experiencing winters that are warmer than the historical average,” Goble said. “However, Colorado’s snowpack is higher than most ski areas in our country. … The ‘champagne powder’ is not going away anytime soon.”
He expects good winter conditions in northern Colorado in particular this coming season, although there were earlier forecasts for less precipitation in these areas.
“For areas like Steamboat and Winter Park, I would be surprised if we had below-average precipitation during La Niña,” he said. “Those mid-winter snowstorms are probably going to be champagne powder, so maybe a little cautious optimism is in order.”
In a blog post from August 13 on OpenSnow.comMeteorologist Alan Smith wrote that “the relative strength of La Niña is also an important factor when it comes to prevailing weather patterns,” adding, “So far, La Niña conditions have developed more slowly than predicted earlier this summer.”
Models from the National Oceanic and Atmospheric Administration currently show a 74 percent chance that La Niña conditions will prevail by the winter of 2024-25, Smith wrote.
“Since 1990, there have been six winters in which weak La Niña conditions have prevailed,” Smith wrote. “The last weak La Niña phenomenon occurred just two years ago in 2022-2023 (which, by the way, was a massive winter for much of the West).”
Whether La Niña will turn into El Niño again, as it did last season, is uncertain, Goble said.
“The last few times La Niña has happened, it has stayed for two or three years, but that’s not necessarily what we expect every time,” he said. “Often La Niña comes through and it’s just a one-year event.”
