The Two Degree Difference: What a La Niña winter means for New York

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NEW YORK STATE (WETM/WFFF/WUTR/NEXSTAR) — Every winter we talk about snow, cold, and ice, and we will for sure see plenty of that this season. But how are things shaping up in comparison to our climate averages?

A La Niña winter is predicted, but what exactly does that mean for New York? How does the weather system—translated from Spanish as “little girl”—affect the winter? Will we be trending cooler, warmer, rainier, or snowier?

The Climate Prediction Center released its winter outlook, ranging from December 2021 through February 2022. It shows slightly cooler than average temperatures for the northwestern portion of the US. The outlook also shows above-average temperatures being favored across the South and most of the eastern US as La Niña climate conditions return for the second winter in a row.

According to NOAA, La Niña is a natural ocean-atmospheric phenomenon marked by cooler than average sea surface temperatures across the central and eastern Pacific Ocean near the equator. This cooling is due to trade winds blowing from east to west. During La Niña events, which push warm water near the equator to the west, which results in an upwelling of colder water. This is why the sea surface temperatures end up lower near the equator during La Niña events.

Cooler ocean waters shift the jet stream—which acts as our steering pattern for weather systems—to the north. Temperature gradients dictate the jet stream, which is pushed farther north due to the change in the temperature gradient from the north pole to the equator. A northward jet stream impacts our winter because its shape alters how weather systems come and go into the region and alter precipitation totals.

The shape of the jet stream digs southward at a specific point, helping usher in warmer air to the north. Above-average temperatures result due to this northward push of warmer air from the south. El Niño, meanwhile, is the opposite, pushing the polar jet stream south to warm winters in the north.

“It really depends where you are in the United States. It will vary by location,” NOAA climate scientist Michelle L’Heureux told Nexstar in August. “The southern tier during a La Nina is often drier than average during the winter, and that often extends into spring.”

That southern tier includes Southern California, the southwestern states, Texas, and the Gulf Coast states through to Florida. Many of those states, especially in the southwest, are plagued by drought, and a La Niña year could make that worse. The opposite is actually true for Northern California and the Pacific Northwest, where La Nina winters tend to bring more precipitation, not less. Later in winter, that extra precipitation tends to hit Ohio and the Tennessee Valley.

How La Niña affects the northeast is the biggest mystery, L’Heureux said. It’s pretty chances of a wet winter slightly edge out chances for a dry winter. The Climate Prediction Center’s seasonal temperature outlook indicates most of the country could see a slightly warmer winter. All but the most northern states are leaning above average. In terms of drought, long-term trends show an end to any drought-like conditions in the northeast this winter, along with worsening conditions in southern portions of the U.S., such as Texas.

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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