It just doesn’t quite feel like another ski season is nearing until we’ve talked about El Niño and La Niña (also known as ENSO, El Niño-Southern Oscillation). These two major weather patterns can greatly influence global climate, and especially temperatures and snowfall across North America. And as the 2024-25 ski season approaches, it looks like a La Niña winter is approaching along with it.
Before talking about El Niño and La Niña, however, it’s important to have some context and understand what defines normal conditions. As the National Oceanic and Atmospheric Administration (NOAA) writes, “During normal conditions in the Pacific Ocean, trade winds blow west along the equator, taking warm water from South America towards Asia.” Cold water then rises from the depths to replace that warm water. This is known as “upwelling.” The cold water then cools the air in the region. This is why San Francisco is known for its cool, foggy summers. As the NOAA continues, “El Niño and La Niña are two opposing climate patterns that break these normal conditions.”
La Niña vs. El Niño
La Niña means that the sea surface temperatures in a large area of the central and eastern equatorial Pacific Ocean (around the equator) are below normal. Conversely, El Niño means that sea surface temperatures are above normal in the eastern tropical Pacific Ocean, and that there’s higher-than-normal air pressure over the western Pacific. These sea surface temperature fluctuations can significantly influence global weather patterns, especially during the winter for the U.S.
This strong influence on winter weather is important because it provides some confidence in the seasonal snow forecast ahead of the start of the ski season. Many people, and even meteorologists, are skeptical of long-range weather forecasts, and especially those that purport to predict amounts of snow or rain several months into the future. Forecasts aren’t typically very instructive for an entire winter in the absence of La Niña or El Niño events. However, when El Niño or La Niña events influence the weather patterns, meteorologists often can provide a more confident seasonal forecast by looking at snowfall and weather patterns from past La Niña seasons. In short, La Niña gives us a historical guide to forecasting the future.
“La Niña tends to organize the wintertime jet stream in a way that favors the Pacific Northwest and Northern Tier of states with the most consistent winter snowfall,” writes OnTheSnow meteorologist Chris Tomer. As Tomer continues, “La Niña tends to leave California and the Southern Tier of states drier and warmer than normal.” This pattern isn’t conducive to atmospheric river setups, and drought can deepen as a result.
What Will La Niña’s Impact Be On This Ski Season?
La Niña has been a dominant weather force in recent years. North America experienced a rare Triple-dip La Niña during the 2022-23 season, as we saw three consecutive seasons of La Niña. This had only occurred 3 times in the last 73 years, according to meteorologist Chris Tomer. And what a winter it was. The 2022-23 ski season saw a number of ski resorts out West, particularly in California and Utah, break snowfall records. That was followed last season by an El Niño event, which dissipated at the end of the spring. A La Niña winter this year would mark the fourth La Niña event in 5 years. A recent study suggests that multi-year El Niños and La Niñas could become more common.
So how is the 2024-25 ski season shaping up? The NOAA recently issued a La Niña Watch, predicting La Niña conditions to emerge in September-November (71% chance), and to persist through January-March of 2025. As the NOAA writes, “This month, the team relies more on the latest North American Multi-Model Ensemble (NMME) guidance, which predicts La Niña to emerge in the next couple of months and continue through the Northern Hemisphere winter.”
As the above graphic illustrates, the Pacific Northwest, northern tier states, and Canada stand to benefit the most from a La Niña pattern. However, that’s not always the case, as evidenced by the 2022-23 ski season, when regions that were expected to be drier and warmer, like California and Utah, had record-breaking winters. Nonetheless, past La Niña patterns provide some context and guidance for what a La Niña winter could hold.
The NOAA’s La Niña Watch stated that the IRI plume has predicted a La Niña event that is weak and short in duration. As the NOAA writes, “A weaker La Niña implies that it would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance.”
This was also reflected in Meteorologist Chris Tomer’s long-range weather forecast, which you can view below. Subscribe to our YouTube channel, where Chris will be sharing twice-weekly snow forecasts beginning in November.
Regardless of how the upcoming La Niña materializes, you can count on snow. Time will tell just how much snow that North America will see. Be sure to subscribe to our newsletter, and follow us on Instagram and Facebook for the latest updates, and download our app, so you can see the latest ski conditions, snow forecasts, and more.
Stay tuned for meteorologist Chris Tomer’s long-range winter forecast for North America. Then once the snow starts flying in November, Chris Tomer will be back sharing twice-weekly snow and weather forecasts.
December 01, 2024
