INDIANAPOLIS (WISH) — The official start of winter is only a short time away.

Year after year, we get to this point of the fall and wonder what this upcoming winter has in store for us. Some of us root for a winter filled with snowstorms, but others dread it. 

A huge factor in what can make or break a winter outlook lies thousands of miles away. That would be El Niño or La Niña.

What is El Niño/La Niña?

Mike Ryan is a senior meteorologist with the National Weather Service in Indianapolis. He says, “What we are talking about when we mention La Niña and El Nino, they are different phases of the El Nino Southern Oscillation. Basically, that’s identifying what the water temps in the equatorial Pacific are doing.”

In a La Niña phase, the water temperatures are below normal off of the western South American coastline. In an El Niño phase, the water temperatures are above normal in these same locations.

Those water temperatures have an impact on the jet stream downwind into North America. Right now, a strong El Niño is in place and expected to last most of the winter.

Usually, this leads to the polar jet stream remaining separate from the subtropical jet stream during the winter months. This results in deeper moisture in the southern.

Similar El Niño winters

Previous years that had similar El Niño patterns provide great value on what we can potentially expect for this upcoming winter.

Ryan said, “We had a stronger one back 7-8 years ago in 2015-2016, which would be one we look at. Then really the two years a lot of folks look at is 82-83 and 1997-98. Those were stronger El Niños.”

In those winters, Ryan said, all of them had below-average snowfall. They also shared the similarity of above-average temperatures in December to February.

Predictions for this winter

Ryan said, “The last few years we have been well below that we have been averaging 10-15 inches. I think, a rough estimate, that’s where we will end up as well this year.”

National Oceanic and Atmospheric Administration’s winter outlook agrees with him. Below-average precipitation and above-average temperatures is where they are leaning.

El Niño gives us an idea of how a winter can play out on a larger scale. But remember, that only gives us a broad idea of what can happen. There are other factors — moisture from the Gulf; smaller-scale jet stream pattern changes; and localized snow bands — that can alter totals significantly on the smaller scale for the season.