Winter 2024-25
It’s never too early to start obsessing about winter weather forecasts and thinking about ski season. While tracking squirrel eating habits and noting the height of the Beargrass in your local ski stash may well be time-tested winter weather indicators, the El Niño Southern Oscillation (ENSO), commonly known by its two opposing influences, El Niño and La Niña, is the gauge most meteorologists use to forecast long-range winter weather patterns.
As a reminder, ENSO is a reflection of sea surface temperatures in the Equatorial Pacific and affects global atmospheric circulation patterns in a somewhat predictable pattern. El Niño reflects warmer than normal sea surface temps, and La Niña reflects cooler than normal sea surface temps. In a nutshell (squirrel reference intended), ENSO alters the jet stream and storm tracks, influencing temperatures as well as rain and snowfall amounts for much of North America.
La Niña vs. El Niño
ENSO has very little impact on our summer climate. However, it does influence hurricane season in North America. In fact, the current trend toward La Niña is why NOAA is forecasting a more active Atlantic hurricane season than normal this fall. Back to winter and skiing . . . ENSO has its strongest influence on our winter weather.
In general, La Niña (cooler sea surface temps) is typically associated with bringing cooler and wetter than average conditions to Northwest regions, including British Columbia, Oregon, Washington, Idaho, Montana and sometimes parts of Utah
On the other hand, El Niño (warmer sea surface temps) is generally associated with wetter than average conditions in the Southwest, including the Sierra Nevada, New Mexico, Arizona, Colorado and sometimes Utah.
Of course, ENSO’s influence is nuanced. It’s science, but it’s not an exact science. Places like Utah, Colorado and Wyoming can really go either way with either scenario, depending on how deep the influence extends. And sometimes the weather just seems to do whatever the hell it wants.
image courtesy climate.org
Current Status: La Niña Watch
So, what can we say about our upcoming 2024-25 winter? Current ENSO status is what NOAA calls a La Niña watch, which means conditions are favorable for the development of cooler Equatorial Pacific sea surface conditions within the next six months.
The NOAA Climate Prediction Center is currently forecasting a favorable 71% chance for La Niña to emerge in September-November 2024 and influence our weather through January-March 2025. The Climate Prediction Center has a great blog that tracks the progress and influence of ENSO. It’s even written so that you don’t necessarily need to be a full-on weather nerd to enjoy it, though it probably helps if you are.
While the Climate Prediction Center (CPC) is arguably the top dog for all things climate-related, there are other climate research centers, most of which are somehow interrelated with the CPC. One such center is the Columbia Climate School’s International Research Institute (IRI) for Climate (part of Columbia University). Interestingly, the IRI is a little less optimistic about the start and duration of a La Niña influence. While they do forecast conditions leaning toward La Niña, their objective model-based ENSO outlook indicates equal chances for La Nina and ENSO-neutral conditions for September-November 2024 with weak and short-lived La Niña conditions in October-December 2024 through January-March 2025.
Of course, it’s the weather we’re talking about here, so nothing is guaranteed. If you’re keen to dig deeper and learn more about ENSO, you should start with La Niña, El Niño and Your Ski Season. It’s a great winter weather primer straight from the Off-Piste Magazine archives.
And, until the snow starts to fly, happy powder dreams . . .
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