El Niño, La Niña and La Nieve: What to expect (or not) this winter
Walking Mountains Science Center
A few hundred years ago a Peruvian fisherman didn’t catch a fish. A couple thousand miles to the north, the world’s first ski bum got stoked. Or something like that.
If you’ve paid even the slightest attention to the mix of science and voodoo religion that characterizes winter snow predictions, then you’ve probably heard the terms El Niño and La Niña. These climatic phenomena have an almost mythic reputation within the snow sports community, with ski and snowboard films bearing names such as “Attack of La Niña” and “Chasing El Niño.” So, what do “The Boy” and “The Girl” have to do with climate science, and more importantly, getting pitted in the back bowls?
El Niño and La Niña refer to patterns of sea surface temperature anomalies in the equatorial Pacific Ocean. El Niño was first observed centuries ago by fishermen who noticed periodic warming in the seas off the Peruvian coast, and a corresponding disappearance of the usually bountiful fishery. This pattern, which was most noticeable around Christmas, was named El Niño, or “The Boy Child.”
El Niño occurs when above average sea surface temperatures, over 0.5⁰ Celsius for weak and 1.5⁰ Celsius for strong El Niño conditions, drive changes in ocean currents, disrupting the “conveyor belt” of nutrients that feeds sea life along South America’s western coast. Beyond just fisheries, however, the El Niño Southern Oscillation which encompasses the periodic shifts between El Niño conditions and its opposite, La Niña, characterized by abnormally cool sea surface temperatures, turns out to be one of the most influential drivers of climate patterns in the Northern Hemisphere.
So, how does this apply to the upcoming winter?
Well, before diving in too deeply, it’s important to note that climate has a lot of moving parts and is notoriously tricky to predict. If you don’t believe me, just search “climate oscillations” on Google. Sometime after reading up on the Pacific Decadal Oscillation and before diving into the Quasi-biennial Oscillation you’ll probably decide to call it a night and just see what the snow stake reads in the morning.
Climate predictions range from model generated probabilities that certain conditions may occur, such as the forecasts issued by National Oceanic and Atmospheric Administration, to, well, whatever they do over at the Farmer’s Almanac. Neither one can tell you when to wax your powder skis but if you must listen to someone, I’d choose NOAA.
That being said, in North America, El Niño and La Niña do cause predictable shifts in regional temperature and precipitation patterns. Unfortunately, these patterns are noticeably less clear in Colorado.
In Vail for example, the two deepest winters in the last 15 years, 2010-2011 and 2007-2008, were both strong La Niña years. However, the next most significant La Niñas, both weak to moderate La Niñas, were 2011-2012 and 2017-2018 — the two worst winters of the past decade. The variability in ENSO’s impact on Colorado stems from our state’s location. La Niña years tend to bring colder and wetter winters to the northern states and warmer and drier conditions to the southern states. Colorado lies somewhere in between.
So, what can we expect this winter? Well, NOAA lists a 35-40% chance that central to northern Colorado will experience warmer than average temperatures and below average precipitation from December through February. This coincides with the moderate La Niña which is currently in place, and NOAA predicts an 85% percent chance that these conditions will continue through the winter.
However, if I were you I wouldn’t hang up my powder skis quite yet. If you had previously heard that it is a La Niña year and expected a rerun of 2010-2011, then perhaps now is a good time to tame your expectations. But, one thing that we can always count on is that at some point, there will be another powder day around the corner. If you need a little help getting stoked, perhaps pick up a copy of “Attack of La Niña” because at the end of the day when it comes to climate predictions, it’s all just a game of probability.
Nathan Boyer-Rechlin is the community outreach coordinator at Walking Mountains Science Center, and despite the climate predictions, is still waxing his powder skis and praying for snow.