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La Niña is back: what that means for North Dakota’s winter

Published: Oct. 20, 2021 at 5:33 PM CDT|Updated: Oct. 20, 2021 at 6:27 PM CDT
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BISMARCK, N.D. (KFYR) - La Niña is officially back and will stick around throughout this upcoming winter, NOAA announced recently. But how does La Niña impact our weather in the Northern Plains?

Meteorologists often turn to ocean temperatures in the Pacific Ocean near the equator to determine if an El Niño or La Niña is present when creating a winter outlook. With a La Niña, stronger than normal winds in this part of the world push warmer water westward, allowing for cooler water to come to the surface farther east.

Current sea surface temperatures show this region of cooler than normal water, indicating a developing La Niña. This impacts the jet stream pattern, leading to downstream effects in the United States.

“So with La Niña, there is typically a blocking high in the Northern Pacific, and that leads to the jet stream arcing over the high, through Canada and into the central U.S. So that is really an easy way for colder air to come from the Arctic and from Canada, and come down into the Northern Plains, which is why with La Niña, we are typically associated with below average temperatures in our winter season,” said Megan Jones, a meteorologist at the National Weather Service Bismarck.

Average La Niña pattern across the United States highlighting where the jet stream usually sets...
Average La Niña pattern across the United States highlighting where the jet stream usually sets up and where temperature and precipitation anomalies usually occur(KFYR)

Even though temperatures were mostly above normal last winter, there was a La Niña in place. And there’s some signals that back-to-back La Niñas can provide.

“For the Northern Plains, it’s much more likely that the second of the back-to-back La Niñas is going to be colder than average,” said Jones.

Looking at winters that were second in a sequence of back-to-back La Niñas and assessing if temperatures were above or below normal throughout that winter on average, nine out of the eleven on record featured cooler than normal temperatures in Bismarck.

List of the 11 winters on record that were second in a sequence of back-to-back La Niñas and...
List of the 11 winters on record that were second in a sequence of back-to-back La Niñas and assessing if temperatures were above or below normal for December through February in Bismarck.(KFYR)

But what about for winter precipitation?

“For us, it’s kind of unfortunate that there is not too much of a precipitation signal with La Niña. A lot of people kind of associate cold with snowy, but that just is not always what we see,” said Jones.

However, with back-to-back La Niñas, some conclusions can be drawn.

“There is some signal that the second of the back-to-back La Niña is maybe favored for slightly above average precipitation,” said Jones.

While La Niña indicates that a cold and possibly snowy winter is ahead, it’s important to remember that there are many other factors and connections to other parts of the globe to investigate. La Niña plays a major role in a winter outlook, but it’s still just a part of the overall forecast.

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