If you're a skier, you've probably heard the term El Niño before. The legendary weather condition has been proven to be kind to North American skiers by producing prodigious snowfall, especially in the Southern Rockies. During the last El Niño year, in 2016, Silverton, Colorado, had received over 160 inches of snow by early December, 15 percent more than what's typical for that time of year. Climate scientists are now predicting a good chance that El Niño will arrive this winter.
But what is El Niño, anyway? Literally translated to English as "the boy” (or as Chris Farley would say, it’s Spanish for “the Niño”), this weather phenomenon is typically associated with heavy precipitation (which includes snowfall) in some regions of the United States and dry spells in others.
To learn more about the science of El Niño and the current predictions for this upcoming winter, we talked with climate scientist and El Niño aficionado Michelle L’Heureux.
L’Heureux has worked for the National Weather Service's Climate Prediction Center for nearly 15 years. As a graduate of the University of Virginia with a bachelor’s degree in environmental science and a master's degree in atmospheric science from Colorado State University, it's safe to say L’Heureux knows her stuff.
POWDER: So, what is El Niño?
MLH: It's the warming of the tropical Pacific Ocean. It occurs every two to seven years. El Niño increases the chances of precipitation across the southern tier of the United States. El Niño, even though it occurs in the tropical Pacific, shifts the jet stream. The jet stream, which flows from west to east across the north Pacific Ocean, brings moisture and then dumps it onto the United States. The pattern tends to shift south and as a result of that shift, you tend to have below-average precipitation across the northern tier of the U.S.
What's the story behind the name El Niño? Is there any significance there?
El Niño was known as far back as the late 1800s through a periodic warming of ocean waters off the coast of equatorial South America. Around Christmas time, fishermen would notice a warming in coastal currents, which they would call El Niño. El Niño can be translated to "Christ's child" and since it was around Christmas time, the association was made.
What's the difference between El Niño and La Niña?
La Niña is the opposite of El Niño; it's the cooling of the tropical Pacific Ocean.
What's the science behind the El Niño predictions?
There's a large monitoring fleet in the tropical Pacific. There's an array of buoys across the tropical Pacific called the Tao Buoy Array. They are fixed in place and measure the sea surface temperatures. Satellite information helps us and there are also ships that have measuring devices onboard that report data to us, too.
What indicators do you look for when predicting El Niño?
Right now, we have seen a gradual warming of ocean temperatures. We want to see them more in certain thresholds before we can say that El Niño has arrived. Things are warming up, but they aren't past the threshold that we need for El Niño just yet. We also look to see if the subsurface of the tropical Pacific has warmed, which usually warms before the surface does. Using these conditions and models, we were able to find a 60 percent chance of El Niño occurring this coming winter.
Can you break down the current El Niño conditions? What do they mean and what should we expect to see?
Right now, what we have in place is an El Niño watch. Odds favor El Niño formation, but they don't guarantee it. A watch means that any time within the next six months conditions are favorable for the development of El Niño. So, as of now, it hasn't yet developed, but there are things happening in the tropical Pacific that lead us to believe that El Niño is favored this coming winter. Right now, we are saying that there is a 60 percent chance of El Niño forming during the fall and then it increases to a 70 percent chance during the winter. So, this still means that there is a 30 percent chance that El Niño will not form.
When people hear El Niño, they usually think of heavy snowfall. Is it fair to associate the two?
It depends where you ski. If you prefer the more southern and middle tier states for skiing, El Niño can be good for you. If you prefer skiing in the northern part of the U.S. like in Oregon, Washington, Montana, and Idaho, El Niño might not be the most favorable.
So, El Niño does effect snowfall. How?
El Niño usually favors a southward shift of snowfall into areas like New Mexico and Southern Colorado. Historically, the Pacific Northwest sees less snowfall. The Northeast typically sees an increase in snowfall, as well. There's always exceptions to these patterns, though.
Should skiers care about El Niño? Is an El Niño prediction something we should be excited about?
Yes. El Niño can give you a little bit of information about what to expect in months in advance, which can be helpful when planning where you want to ski in the coming winter.