Frigid temperatures this weekend prompt cold weather advisories

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The National Oceanic and Atmospheric Administration says the odds of a colder-than-average winter in the Upper Midwest appear to be higher than average this year thanks to a third straight 

However, a warming trend driven by climate change may be stronger.

So will La Niña or climate change win out this winter? Let’s assess. 

winter outlook released by NOAA on Thursday

 is based largely on the ongoing La Niña event in the tropical Pacific Ocean. This is now the third straight La Niña year. That’s happened only two other times since 1950 (1973-1976 and 1998-2001).

La Niña winters historically produce colder-than-average winters in Minnesota about 70 percent of the time. 

NOAA’s winter outlook also calls for equal chances for above or below-average snowfall across most of Minnesota. The only area favoring above-average snowfall is the tip of Minnesota’s Arrowhead region surrounding Grand Marais. 

It’s statistically true that Minnesota winters skew colder than average in most La Niña years, but the climate change forcing the effect of warmer winters in Minnesota appears to be stronger overall.

The Duluth National Weather Service office makes some good points with their 

 Thursday. Here are some data points that stand out to me. This particular data is for Duluth:

So you can see the character of the past two winters have been very different, even though both were La Niña winters.

Now let’s look at the effect of climate change on Minnesota winters.

As our climate shifts, winter is the fastest-warming season in Minnesota. NOAA data and 

 show Minnesota winters have warmed by 5.7 degrees on average since 1970. 

So the climate change forcing signal (+5.7 degrees) is actually stronger than the La Niña cooling signal (-2 degrees) in Minnesota.

So the variability of individual La Niña events and the background forcing of warmer winters due to climate change make for a high degree of uncertainty in Minnesota’s winter forecast this year. 

I’m much more confident in a forecast of warmer-than-average winters in El Niño years that favor warmer-than-average temperatures in Minnesota. In El Niño years, both the 

 and the climate change seasonal forcing factor are in alignment.  

Weather and Climate News

Updraft® - Minnesota Weather News

Paul Huttner

Author

The National Oceanic and Atmospheric Administration winter outlook released Thursday favors cold along with equal chances for above or below-average snowfall.

Minnesota winter outlook: Will La Niña or climate change rule?

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