Will the super El Niño bring super snow?

 This fall and winter, southwestern Colorado will experience the impacts of super El Niño conditions in the Pacific Ocean, which will help shape precipitation, temperatures and storm conditions.

Often, El Niño is associated with average or above-average precipitation totals during winter. Will a super El Niño lead to a super winter with extremely high precipitation? What makes an El Niño super anyway? We turned to the National Weather Service (NWS) to find out.

Grand Junction-based NWS Meteorologist Matthew Aleska explained that the term El Niño describes warmer-than-average sea surface temperatures in the equatorial Pacific Ocean.

During neutral conditions, Aleska said, trade winds push warm surface waters across the Pacific, from near the west coast of the U.S. and South America towards Asia. These waters are then replaced by colder water moving up from deeper in the ocean, cooling the surface.

However, during an El Niño event, the trade winds weaken, causing less surface water to be pushed west across the Pacific and leading to warmer surface water temperatures in the eastern Pacific near the U.S. and South America.

These warmer temperatures and the changes in atmospheric circulation that they cause contribute to several meteorological patterns in the U.S., Aleska said, including a southward shift in the Pacific jet stream and increased activity on this southern storm track.

This pattern tends to benefit the southwestern and southern U.S., he said, since the more southerly jet stream and increased storm activity along this track tends to bring more precipitation to these areas.

In Colorado, this tends to have the greatest benefit for the southern portion of the the state, said Aleska, with the San Juan Mountains and nearby areas often receiving increased precipitation. The impacts are more mixed in the center and north of the state, he said, with it being a coin flip whether El Niño will lead to significant precipitation increases.

The strength of an El Niño event is determined by how far the Pacific Ocean surface temperatures are above average, he said, with stronger El Niño events being associated with warmer temperatures.

This year may be one of the strongest El Niño events on record, Aleska said, with temperatures in the Niño 3.4 region in the central and eastern equatorial Pacific currently already surpassing the two degrees above average threshold that defines a very strong or super El Niño and projected to continue rising.

However, Aleska said that a super El Niño event is not a surefire path to a heavy winter.

El Niño events like that projected for this winter are rare, he said, with only three in the winters of 1982-1983, 1997-1998 and 2015-2016 in modern records. Of these winters, Aleska said that only 1982-1983 resulted in a winter with significantly more snow than average, while 1997-1998 and 2015-2016 both had average amounts of snow.

This makes projecting an outcome from the current El Niño event very difficult, Aleska said.

“The one thing we can hang our heads on is more active storm track to the south,” he said. “So there’s potential that we could see more snowy storms that go down that way and more snow for the southern mountains, in the San Juans. But whether overall, the course of the whole winter, whether that’s going to be above normal or near normal, that’s, um, flip a coin; it could go either way on that regard.”

Shawn and Arleen Prochazka, retired Air Force meteorologists who run the weather information outlet Pagosa Weather in Pagosa Springs and serve as NWS Weather Ready Nation Ambassadors for Archuleta County, added that a stronger El Niño might be less likely to bring a heavy winter than a weaker one.

They said that stronger El Niño events tend to shift the jet stream and storm track further south than weaker El Niño events, potentially directing storms that would have hit southwestern Colorado in a weaker El Niño year south into New Mexico instead.

Aleska said that, with the southern storm track, south-facing mountain slopes will likely have higher snow accumulations than north-facing ones due to typical storm flow patterns. He added that the impacts of these flow patterns are harder to predict at lower elevations and in valleys, although valleys with nearby southern mountains, such as the Gunnison Valley, may be shielded from some storms.

The impacts of El Niño also extend beyond the winter, Aleska said, with southwestern Colorado already experiencing some of them now and likely to continue experiencing them early next spring.

He said that the wet fall conditions the area is currently experiencing are a product of the El Niño event and that similar wet conditions are likely to continue into March 2027, after which forecasting suggests that the El Niño conditions will recede back towards neutral.

He said that these wet fall and spring conditions are typically easier to predict than the winter impacts of strong El Niño events. Aleska said that these predictions are panning out this fall, with September seeing significantly above average precipitation across the region and the trend appearing likely to continue into October.

For example, he said that the Automated Surface Observing System at the airport in Durango, Colorado recorded 6.2 inches of rainfall in September, massively above the average rainfall of 2 inches.

“We are going into a period where we’re staying active, still going to get more moisture and that could be the result of the strong El Niño because they tend to see more of a wetter fall and wetter spring during those strong El Niño events,” Aleska said.

However, both Aleska and Shawn and Arleen Prochazka cautioned that the current wet conditions and the historically strong El Niño are not a guarantee of future winter weather.

“When you hear the term super El Niño, you think like, ‘Oh, we’re gonna have a really good winter, really well above normal snow,’” said Aleska. “But, you can’t with great certainty say that just because we only have three examples and only one of those three was a major snow year whereas the other two were average.

“Just because it says super or it’s strong doesn’t mean that it’s gonna be more intense. It just basically means that you’re having temperatures in the ocean and a favored storm track down south. So, it could lead to more snow, but it’s not 100 percent certain that it would end up happening.”