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Weather Wise: La Niña

Weather Wise: La Niña
Posted at 6:39 PM, Sep 13, 2021
and last updated 2021-09-13 20:49:22-04

Although summer is not even over yet, this week’s Weather Wise is going to take a look at the winter. Specifically, how La Niña will once again influence the upcoming season here in Montana, but likely not like last year’s weak winter.

Yes, it was a La Niña winter last year, yes it was a lackluster winter and yes, La Niña winters are typically colder and snowier than normal. So what happened last year then?

Approximately 30 percent of La Niña years have mild, drier winters than normal. That's what happened in the winter of 2020-2021. A larger, more dominant pattern in the Pacific called the “Pacific Decadal Oscillation” overruled La Niña, but this likely will not happen again.

With La Niña strengthening in the Pacific, the Climate Prediction Center is expecting a good chance of above-average precipitation, especially west of the Continental Divide for the winter months. temperatures are likely to be close to average, which of course average in Montana can be pretty darn cold.

A similar situation happened just a few years ago. after the record-breaking fire season and hot summer of 2017, a weak to moderate La Niña developed for the winter of 2017-18.

Here in Montana, mountain snowpack was generally well above average by the end of winter, with many of the state's mountains around 150% of normal snow water equivalent.