Keystone Ski Resort received snow the night of Saturday, Sept. 21 and into Sunday. After a flurry of early-season storms, the High Country is slated for drier weather heading into October and beyond. Experts predict a slower start to the 2024-25 winter season with snow picking up later on.
Katie Young/Keystone Resort
If one thing’s nearly certain for the 2024-25 ski season, it’s that atmospheric patterns that can dictate snow conditions will be different from last year.
Ahead of winter, the continental U.S. is expected to shift into a La Nina pattern generally characterized by more precipitous, cooler weather in the north and drier, warmer weather in the south. La Nina occurs when surface temperatures in the equatorial Pacific Ocean off the coast of South America fall below average, pushing the jet stream north.
During the 2023-24 season, the opposite pattern, El Nino, was present, which can have the inverse effect.
In a blog post on OpenSnow.com earlier this month, meteorologist Sam Collentine said forecasts favor a “weak” La Nina forming — meaning accompanying snowfall could be on the lower end of what La Nina typically brings.
Collentine cautioned against taking any long-range prediction as gospel, adding, “We know that skiing quality improves and degrades with storm cycles that last a few days to a week.” Still, by analyzing data from past weak La Nina seasons, Collentine provides a glimpse of what this year could have in store.
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I-70 corridor
An OpenSnow analysis identified six ski seasons dating back to 1990 when a weak La Nina pattern was present. Those are 2000-01, 2005-06, 2008-09, 2016-17, 2017-18 and 2022-23.
When looking at historical trends for the Interstate 70 corridor, Collentine compares the seasons to the 30-year median snow level at the Berthoud Summit SNOTEL station, which on March 31 usually has a normal snow-water equivalent of 18.2 inches. SNOTEL sites are sensors that measure the state’s snow fields by recording how many inches of liquid water is held within the snowpack, called snow-water equivalent.
Collentine’s analysis found that one out of the six La Nina years produced well above-normal snowpack, four produced near-normal snowpack, and one produced well below-normal snowpack.
Here’s where snowpack levels stood at the Berthoud SNOTEL sensor on March 31 for each season:
2000-01: 18.5 inches (102% of normal)
2005-06: 20.9 inches (115% of normal)
2008-09: 19.2 inches (106% of normal)
2016-17: 16.7 inches (92% of normal)
2017-18: 14.8 inches (81% of normal)
2022-23: 18.6 inches (102% of normal)
Additionally, Collentine noted that the increase in snowpack during each of those seasons was greatest in December and January and less so during the beginning and end of the ski season.
For the 2024-25 season, “This gives us a signal that the shoulder seasons could be below-normal, while the core winter months could be near to above-normal,” Collentine stated.
He added, “Overall, history tells us that I-70 tends to be near normal to potentially slightly above normal for snowfall during weak La Nina winters.”
Steamboat
Looking north to Steamboat Springs, Collentine compares those same six seasons to the average snowpack recorded at the Tower SNOTEL station near Steamboat — which on March 31 usually has a normal snow-water equivalent of 42 inches.
The two seasons that produced well above-normal snow were 2005-06 and 2022-23. Two produced near-normal snowpack (2008-09 and 2016-17) while two were well below normal (2000-01 and 2017-18). Below are the findings for each season:
2000-01: 36.0 inches (86% of normal)
2005-06: 51.3 inches (121% of normal)
2008-09: 44.9 inches (107% of normal)
2016-17: 38.9 inches (93% of normal)
2017-18: 34.5 inches (82% of normal)
2022-23: 51.9 inches (124% of normal)
Aspen
South of I-70 in the Aspen-Snowmass area, Collentine compares the previous seasons to the median snowfall — rather than snow-water equivalent — recorded in Aspen, which is 165 inches.
In that analysis, two out of the six La Nina seasons saw well above-normal snowfall (2008-09 and 2022-23), three saw near-normal (2000-01, 2005-06, 2016-17) and one was below-normal (2017-18). Below are the findings for each season:
2000-01: 151 inches (90% of normal)
2005-06: 159 inches (95% of normal)
2008-09: 201 inches (122% of normal)
2016-17: 158 inches (95% of normal)
2017-18: 127 inches (76% of normal)
2022-23: 218 inches (131% of normal)
As with the I-70 corridor, the greatest increase in snowfall for both Steamboat and Aspen was recorded during December and January for each of those seasons.
Despite what historical trends may say, Collentine added, “To have the best chance of enjoying the deepest powder, our recommendation is to dial in your plans 7-10 days in advance.”
“Sometimes, longer-range forecasts can identify possible storms 1-2 weeks (or longer) in advance, but often, forecast confidence in the details of each storm only begins to increase when the system is about one week away or closer,” he continued.
Nearer-term predictions
The High Country over the past month experienced a flurry of snowfall, the first significant storms of the 2024-25 season. But the next few weeks could be much drier.
“The weekend storm was a fun taste of winter, but we’re going back into a more typical fall weather pattern to close out September with peak fall color and dry conditions,” wrote OpenSnow founding meteorologist Joel Gratz in a Sept. 23 post.
A three-to-four-week outlook from the Climate Prediction Center shows greater chances for above-normal temperature and below-normal precipitation in Colorado from now through Oct. 18.
A longer-range forecast shows that in October, November and December the High Country has a 50% to 60% chance of seeing above-normal temperature and a 33% to 40% chance of below-normal precipitation.
“Most signs point to near-average snowfall with a higher probability for more snow during the ‘core’ of the season in December and January, and perhaps less snow during the early and late season,” Gratz stated. “That said, similar past seasons ranged from well below-average snowfall to near-average snowfall to well above-average snowfall. So … yes, anything is possible.”
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Publish date : 2024-09-24 16:50:00
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