(Image courtesy of WMR)

Before we look ahead to Montana’s 2024-2025 winter season forecast, it's important to remember that any winter outlook will contain an inherent degree of uncertainty. However, thanks to the available historical weather data, there are a few clues that we can keep an eye on.

Long-range forecasts are rarely accurate. These forecasts cover 3-6 months but we know that skiing quality improves and degrades with storm cycles that last a few days to a week.

La Nina, Explained

The term La Niña refers to the large-scale ocean-atmosphere climate phenomenon linked to periodic cooling in sea-surface temperatures across the central and east-central equatorial Pacific.

La Niña represents the cool phase of the ENSO cycle and means that the ocean water temperatures are cooler than average.

La Nina Forecast for the Winter of 2024-2025

"ENSO Neutral" conditions (neither La Niña nor El Niño) have persisted through the summer of 2024 and long-range models have been projecting a higher-than-average chance of a La Niña taking over during the winter of 2024-2025.

The weekly Nino-3.4 region index (sea surface temperatures in the east-central Pacific) anomaly has dropped from 1.8°C during the 2023-2024 winter season to -0.2°C as of October 14, 2024.

A similar change from El Niño to a weak La Niña last occurred ahead of the 2016-2017 winter season.

Thanks to OpenSnow meteorologist Alan Smith, we have identified six winters since 1990 in which weak La Niña conditions were present:

• 2000-2001
• 2005-2006
• 2008-2009
• 2016-2017
• 2017-2018
• 2022-2023

We will use these winter seasons that featured a weak La Niña as “analog” years and pull SNOTELdata from six of Montana’s popular resorts for this analysis.

WEST of the CONTINENTAL DIVIDE:

(Image courtey of WMR)

Whitefish Mountain Resort

After looking back at the six most recent weak La Nina years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 36.1 inches at the Stahl Peak Snotel at 6030’ in the Whitefish Range 37 miles north of Big Mountain (Whitefish Mtn Resort), I've found that the median SWE near Whitefish during those weak La Nina years is 34.5 inches on March 31 or 95% compared to the 30-year normal.

SWE on March 31 During Weak La Niña years

• 1991-2020: 36.4” (30-year normal)
• 2000-2001: 19.8” (54%)
• 2005-2006: 38.3” (105%)
• 2008-2009: 30.7” (84%)
• 2016-2017: 40.0” (110%)
• 2017-2018: 43.3” (119%)
• 2022-2023: 28.0” (77%)

The cold and powdery winter of 2017/18 is the standout above with well above-average snowfall. Two winters, 2005/06 and 2016/17 were also above normal, and two winters, 2008/09 and 2022/23 below normal. The winter of 2000/01 was well below normal.

When looking for monthly trends while compiling the above data, I noticed that weak La Nina seasons tend to start at, or just slightly below the 30-year median SWE for the months of November and December. The snowfall then looks to stabilize to around average SWE during January, February and March.

A more positive observation is that current La Nina oceanic readings resemble the 2016/17 winter when the March 31 SWE was 40 inches or 110% above the 30-year average. Whitefish is my home mountain, and I remember that season well with over 400 inches of total reported snowfall.  

Montana Snowbowl

Next up, ‘The Bowl’. Researching the six winters with similar weak La Nina readings and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 32.0 inches at the Stuart Mountain Snotel at 7400’ next to Montana Snowbowl, I've found that the median SWE on those years is 34.3 inches on March 31 or 107% compared to the 30-year normal.

SWE on March 31 During Weak La Nina’s

• 1991-2020: 32.0” (30-year normal)
• 2000-2001: 21.6” (68%)
• 2005-2006: 35.0” (109%)
• 2008-2009: 33.8” (106%)
• 2016-2017: 34.8” (109%)
• 2017-2018: 39.7” (124%)
• 2022-2023: 29.6" (93%)

Four out of the six weak La Nina years produced above-normal snowfall readings on March 31, with one close to the median, and one, 2000-01 well below the median.

When researching the above, I noticed a pattern of average to slightly below average snowfall during the start to the season (November, December) with a rebound to slightly above average for the remainder of the season through March.

I also remember the storm pattern during the mid-winter months of 2022/23 that really favored West Central Montana where Snowbowl is situated. It’s a positive sign but take it with a grain of salt, preferably with tequila on a pow day at the Bowl’s legendary Last Run Inn.

Lost Trail Powder Mountain

After looking back at LT’s six most recent significant La Nina years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 23.0” inches at the adjacent Saddle Mountain Snotel at 7940’ I've found that the median SWE at Lost Trail during those weak La Nina years is 23.9 inches on March 31 or 104% compared to the 30-year normal.

SWE on March 31 During Weak La Nina’s

• 1991-2020: 23.0" (30-year normal)
• 2000-2001: 14.5” (63%)
• 2006-2006: 27.6” (120%)  
• 2008-2009: 25.2” (110%)
• 2016-2017: 22.6” (98%)
• 2017-2018: 32.9” (143%)
• 2022-2023: 21.9” (95%)

Three out of the six weak La Nina years produced end of season above-normal snow water equivalent (SWE) totals for Lost Trail on March 31^st with the exceptional winter of 2017/18 leading the way. There were two near average winters in 2016/17 and 2022/23, with the drought plagued winter of 2000/01 as the lone outlier.    

Analyzing the monthly SWE medians of these six weak La Nina winters indicated a slow start during November, nearing average by the end of December, with average to slightly above average snowfall during January through March. I was a passholder at LT for many years and a ‘seasonal average’ snowfall delivers many powder days. I may be chasing some ‘Powder Thursday’s more frequently this coming season. Fingers crossed.

EAST of the CONTINENTAL DIVIDE: 

(Image couresy of BSR)

Big Sky Resort

After researching the six most recent weak La Nina years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 17.6” inches at the Lone Mountain Snotel at 8880’ I've found that the median SWE at Big Sky during those six La Nina years is 21.4 inches on March 31 or 122% compared to the 30-year normal.

SWE on March 31 During Weak La Nina years

• 1991-2020: 17.6” (30-year normal)
• 2000-2001: 13.3” (76%)
• 2005-2006: 22.0” (125%)
• 2008-2009: 20.8” (118%)
• 2016-2017: 16.3” (93%)
• 2017-2018: 24.9” (141%)
• 2022-2023: 22.9” (130%)

Two out of the six weak La Nina winters, 2017/18 and 2022/23 produced well above-average snow water equivalent (SWE) on March 31. Two above-average winters in 2005/06 and 2008/09, with 2016/17 near average, and the dry winter of 2000-01 well below average. On paper, these historical numbers look the most optimistic of all the resorts I researched.

Being this my tenth season writing the Montana Daily Snow and I remember covering the weather during the epic winters of 17/18 and 22/23 quite fondly.  During those seasons most of the snowfall came after the first of the year and continued building through February and closed out especially heavy in March and early April.

Analyzing the monthly SWE medians of these six analog years it appears to signal a slow start in November, but quickly picking up in mid to late December to around average, with above average monthly snowfall numbers from January through the end of March.

Could we see a rerun of this pattern in 2024/25? I’m optimistic…but the caveat is that it’s just a scientific guess.

Bridger Bowl  

Looking back at the six most recent weak La Nina years and comparing them against the 30-year median snow water equivalent (SWE) on March 31 of 20.8 inches at the Brackett Creek Snotel at 7320’ near Bridger Bowl, I've found that the median SWE near Bridger during six ski seasons is 21.9 inches on March 31 or 105% compared to the 30-year normal.

SWE on March 31 During Weak La Nina years

• 1991-2020: 20.8” (30-year normal)
• 2000-2001: 13.3” (64%)
• 2005-2006: 22.0” (106%)
• 2008-2009: 21.7” (104%)
• 2016-2017: 19.2” (92%)
• 2017-2018: 30.1” (145%)
• 2022-2023: 22.1” (106%)

Four out of the six weak La Nina years reported produced above 100% (of average) snow water equivalent (SWE) on March 31. Like nearby Big Sky, the 2017/18 season really delivered the pow days, ending the season at 145% of average snowpack.

The Brackett Creek data pointed to a slightly slow start to the season with a significant uptick in snowfall starting in January and continuing that way through the end of March. While not as prone to deep late season storms as nearby Big Sky, Bridger tends to rack up consistent light to moderate snowfall amounts, especially under colder weak La Nina winters. Good reasons for optimism in Bozeman for the upcoming winter. 

Red Lodge Mountain

Over at Red Lodge Mountain, the Cole Creek Snotel sits at an elevation of 7850’ on the mountain’s backside, and thus is an excellent source for snowfall/snowpack weather data from the last six weak La Nina years. Comparing against the 30-year median snow water equivalent (SWE) of 12.5 inches at March 31^st I've calculated that the median SWE at Red Lodge during the six weak La Nina years is 12.1 inches (March 31) or 97% compared to the 30-year normal.

SWE on March 31 During Weak La Nina’s

• 1991-2020: 12.5” (30-year normal)
• 2000-2001: 9.6” (77%)
• 2005-2006: 9.9” (79%)
• 2008-2009: 15.8” (126%)
• 2016-2017: 10.5” (84%)
• 2017-2018: 13.6” (109%)
• 2022-2023: 14.9” (119%)

Three out of the six weak La Nina winters produced above-normal snow water equivalent (SWE) for Red Lodge Mountain on March 31. Two of these winters, 2008/09 and 2022/23 delivered well above the SWE median. The flip side is that the other three seasons, 2000/01, 2005/06, and 2016/17 delivered below-average snowfall.

The monthly median Snotel data at Red Lodge Mountain over the last six weak La Nina winter seasons points to above average numbers in March and April. This will sound quite familiar to Red Lodge locals as the mountain is infamous for its deep late season snowstorms. The numbers also point to below average snowfall during November extending through January.

Other optimistic weak La Nina indicators point to frequent cooler than average temperatures, which may come in handy for the extensive early season snowmaking that Red Lodge is also known for. They typically are one of Montana’s first resorts to open the season. This year they hope to open on November 29^th.

(Image courtesy BSR)

2016-2017 Winter Season

As mentioned earlier, the Niño-3.4 region index anomaly as of October 14, 2024, is down to -0.2°C, which is similar to where it was ahead of La Niña conditions that developed during the late summer of 2016.

Since this last occurred back in 2016, let's take a look back at the snowfall during the 2016 – 2017 season. Data was limited to the major resorts, courtesy of BestSnow.net.

• Big Sky Resort:  323” (111%)
• Whitefish Mountain Resort: 440” (147%)
• Bridger Bowl Ski Area: 251” (84%)

Overall, the history of the past six weak La Nina winters tells us that Montana’s Northern Rockies tend to be near to slightly above average in snowfall.

Having said all of this, for skiers and snowboarders, keep in mind that when it comes to finding the best conditions, it’s all about timing. To have the best chance of enjoying the deepest powder, our recommendation is to book a trip 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.

Every OpenSnow All-Access account provides 10-day snow forecasts, expert analysis from local forecasters, 3D weather maps, and custom snow alerts to help you find the deepest snow and the best conditions all winter long.

Thanks for reading, let’s start doing our pre-winter rituals for an off-the-charts 2024/25 winter in the Northern Rockies. Stay tuned for my regular Montana Daily Snow updates starting in November. Powder Out.

Bob Ambrose