NOAA Climate Prediction Center
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El Niño who? This is La Niña’s time.
According to a new forecast from the National Oceanic and Atmospheric Administration, La Niña could begin any day now, and the country is officially on watch. But what does that mean for Denver?
In a La Niña pattern, trade winds are stronger than usual, so more warm water goes toward Asia while colder water comes to the Pacific coast of America.
“These cold waters in the Pacific push the jet stream northward,” the NOAA forecast explains. “This tends to lead to drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than normal in the South and cooler than normal in the North. La Niña can also lead to a more severe hurricane season.”
Colorado is right on the cusp of the polar jet stream, so in the past, La Niña has had a variable impact on Denver’s weather. Still, six of the seven most recent La Niña effects have coincided with below-average snowfall in Colorado. Denver’s average snowfall is 56 inches, so that’s the number to monitor going forward.
Though Denver is experiencing a hot, dry fall as predicted, winter forecasts in Colorado have predicted high snowfall this year in the western half of the state. Similarly, La Niña could lead to less snow in the southern half of Colorado, but more snow in the northern half.
The latest NOAA prediction suggests a weak La Niña, with a 60 percent chance of setting in by the end of November. The effect could last through January or March 2025.
Last winter was governed by El Niño, which has the reverse effect: Northern states are drier and southern states are wetter. It could even out for Colorado, which is stuck in the middle during both weather patterns.
