Ski Season and El Niño

Ski Season and El Niño

Everyone likes a glimpse of the future, especially skiers and snowboarders who are planning for winter. In most parts of the country people are hiking up mountains rather than skiing down them now, but, looking ahead, many are wondering – how much snow will there be this winter? In part, the answer to this question depends on El Niño.

During El Niño, trade winds weaken over the tropical Pacific, which slows the upwelling of cold water near the coast of South America. This makes the tropical Pacific unusually warm.

El Niño is one part of the El Niño-Southern Oscillation (ENSO), a combination of changes in the ocean and atmosphere stemming from the tropical Pacific Ocean. During the other part of ENSO, La Niña, the trade winds grow stronger across the Pacific and the surface water is unusually cold.

What does the tropical Pacific have to do with North American skiing? While the source of El Niño is a pool of warm water in the tropical Pacific, its effects reach around the world including having an impact on winter temperatures and snowfall in North America. How patterns of the atmosphere in one location affect weather thousands of miles away are called teleconnections.

Meteorologist Joel Gratz (who is an alumni of our Undergraduate Leadership Workshop) recently posted about the impact of El Nino on the upcoming ski season (here's his article on OpenSnow). He reviewed what several different models predict for the upcoming winter. His main takeaway: “most models show above average precipitation in the southwestern US while the northern Rockies of the US and Canada may see below average snowfall. For all other locations, the forecast is tough to pin down.”

However, Joel notes that “about 10% of the storms produce half of the winter’s snowfall” and the timing of big storms cannot be determined by long range forecasts. Long range seasonal forecasts give a general idea what’s going to happen, but they can’t tell us how many of those large storms and powder days skiers will see in February. So keep watching the weather forecast this winter. Using models designed to project several days in advance, weather forecasts are able to forecast individual storms.

Here’s the outlook according to NOAA for the winter months based on both historical weather data and future predictions:

Temperature for December, January, and February are predicted to be warmer than usual  in the northern continental U.S., Alaska, and southern Canada (orange colors), and cooler than normal temperatures in the South and Southeast U.S. (blue colors).
Credit: NOAA via OpenSnow

 

Precipitation during December, January, and February is predicted to be more than usual in the Southwest, South, and Southeast U.S. (green colors) and less than usual in the Northwest and Midwest U.S. and parts of Alaska (tan colors).
Credit: NOAA via OpenSnow

Learn More About El Niño