Will our mild bias linger into December?

Longer-range products suggest a milder than average December.

NOAA week 3 and 4 temperature outlook
NOAA week 3 and 4 temperature outlook
NOAA

Hello La Niña? We’re waiting.

You may have read that there’s a La Niña event underway in the tropical Pacific Ocean. Colder than average water temperatures persist this fall across the equatorial Pacific.

Tropical Pacific SST departures from average
Tropical Pacific SST departures from average
NOAA

That periodic cooling of ocean temperatures in the tropical Pacific can generate changes in weather patterns across the globe. La Niña winters statistically skew colder and snowier for parts of Minnesota and the Upper Plains.

Typical La Nina winter pattern
Typical La Nina winter pattern
NOAA

So far November is running about three to more than six degrees warmer than average across the Upper Midwest and Great Lakes.

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November temperature departure
November temperature departure
Midwest Regional Climate Center

And while we still enjoy the day to day ups and downs of periodic warm and cold fronts, current forecast trends suggest our milder than average air overall may hang around into December this year.

Check out The National Oceanic and Atmospheric Administration’s week 3 to 4 temperature outlook.

NOAA week 3 and 4 temperature outlook
NOAA week 3 and 4 temperature outlook
NOAA

Mild December too?

NOAA’s CFS2 product gauges the chances and magnitude of above or below average temperatures on longer time scales. Recent NOAA CFS2 outlooks for December show a strong mild bias bull’s eye right across Minnesota and the Upper Midwest.

NOAA CFS2 temperature outlook for December 2020
NOAA CFS2 temperature outlook for December 2020
NOAA

It remains to be seen if December will remain milder than average. It’s also not a slam dunk that La Niña winters end up colder and snowier than average overall. But we’re off to a big start on snow this season.

And I can recall several La Niña winters that started mild in the first half, then turned bitterly cold for the second half of winter with severe polar vortex outbreaks.

Stay tuned.