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WeatherWise: End of a La Nina era

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Posted at 4:11 PM, Feb 13, 2023

An exceptional and oddly behaving La Niña has come to an end in the Pacific which will spell changes for Montana and much of the world.

La Niña is the cooling of ocean water near the equator in the Pacific Ocean. This natural phenomenon usually has a global weather implications and historically has resulted in colder and snowier winters for Montana, the Northern Rockies and the Pacific Northwest.

La Niña normally lasts nine months to a year, but this recent La Niña lasted an unprecedented three years. So the last three winters should have been colder and snowier than normal here in Montana but that has not been the case. The last two winters were mild with below-average snow, and while this winter has had its moments of snow and below-normal temperatures, overall temperatures and snow have been close to average. So not only was this most recent La Niña unusually long, it was unusually dry and mild.

So what's next? It is likely that old pal El Niño returns this summer into the fall. El Niño and La Niña have less effect on summer weather than winter weather. If a stronger El Niño were to develop it might be the inverse of what was supposed to happen the last few years. Montana winters with El Niño are typically warmer and drier than normal. As La Niña ends these next few months and before El Niño pattern develops, it's likely Montana experiences normal conditions through the rest of winter and spring.

However. more research is needed to further understand La Niña, El Niño, and anomalies like what was just experienced over the last few years as things did not go as planned.