The 2022-23 ski season, in which we saw a rare triple-dip La Niña event, was record-breaking for a number of North America ski resorts out West. The season ended with a bang, as ski areas across parts of the West, predominantly in California and Utah, broke all-time snow records. Finally, we said so long to La Niña, after a three-year run, and said hello to El Niño.
What is the difference between La Niña and El Niño?
So what is El Niño and La Niña, and what’s the difference between the two? A La Niña event means that the sea surface temperatures (SST) in the eastern tropical Pacific Ocean (around the equator) are below normal and that there’s lower-than-normal air pressure over the western Pacific. During El Niño events, on the other hand, the sea surface temperatures are above normal in the eastern tropical Pacific Ocean and there’s higher-than-normal air pressure over the western Pacific. La Niña events and El Niño events oscillate every 2-7 years, and these weather events can immensely impact the ski season and the amount of snowfall that different mountain regions receive.
As Meteorologist Chris Tomer shared with us, “El Niño is defined by warmer than normal (at least 0.5C above normal) sea surface temperatures in the South Pacific Ocean near the Equator over a three month period.” When SSTs are at least 1.5C above normal, it’s considered a strong El Niño, and a super strong El Nino when SSTs are at least 2.0C above normal. As Chris Tomer continued, “We’re currently seeing a strong El Niño, while some of the model guidance suggests we’re heading for a super strong El Niño.” Only five winter seasons since 1950 have seen a super strong El Niño event.
Chris shared more about the difference between El Niño and La Niña events in his long-range winter forecast:
“During La Niña years the polar jet stream dominates. During El Niño years, on the other hand, the subtropical jet stream dominates. By January through April, that subtropical jet stream looks especially enhanced. It will mirror the enhanced subtropical jet stream from May-July 2023 when heavy precipitation and a parade of storm systems hit the Southern Tier. Additionally, atmospheric river (AR) setups are likely along with large East Coast storm systems.”
El Niño and La Niña impact on past ski seasons
Long-range winter forecasts aren’t always instructive, and especially during the absence of La Niña and El Niño. La Niña and El Niño weather patterns serve as a historical guide, with meteorologists able to look at the data and forecasts from past seasons to make informed forecasts when those patterns reemerge. Yet long-range snow forecasts, even in La Niña and El Niño years, don’t always match up with actual snowfall. Last year, for example, California was forecasted to have a warmer and drier ski season as a result of the La Niña event. However, multiple California ski areas broke their all-time snowfall records.
What will El Niño’s impact be on this ski season?
The NOAA in an update earlier this month about El Niño conditions wrote that it anticipates a greater than 95% chance of El Niño through January – March 2024. As Chris Tomer shared in his long-range forecast, the data suggest a drier than normal winter for most of the West. Yet it could still be a big winter for ski areas around Lake Tahoe, Mammoth, and in Colorado. Chris forecasts a wetter than normal winter for the East, where most New England ski areas could see above above-normal snowfall.
Whatever the upcoming ski season holds with an El Niño event, we couldn’t be more excited. Though fall is just underway, snow is already flying at some ski areas, while other ski areas are already making snow thanks to low temperatures. Download our app, follow us on Instagram and Facebook, and subscribe to our newsletter for the latest updates. Chris Tomer will be back in November with twice-weekly Snow Before You Go forecasts.
Header: @Andrew Taylor Vail Resorts