Is a polar vortex outbreak in sight?

First, a winter storm targets western and southern Minnesota Friday

Snowfall potential Friday
Snowfall potential Friday.

Welcome to the warmest day across southern Minnesota since Christmas Eve. The mercury nudged 40 degrees at Minneapolis-St. Paul International Airport around 1 pm Wednesday.

Temperatures in the Twin Cities
Observed temperatures in the Twin Cities Wednesday.
National Oceanic and Atmospheric Administration / Federal Aviation Administration

So far, January temperatures are running about 10 degrees below average in the Twin Cities and much of Minnesota.

Light wintry mix overnight

We could see a light wintry mix overnight into early Thursday morning across parts of Minnesota. Patchy light snow and light freezing rain could cause some slick roads early Thursday.

Here’s the precipitation map for 1 a.m. Thursday:

Forecast weather conditions for 1 am Thursday
Forecast weather conditions for 1 a.m. Thursday.

Thursday brings another relatively mild day for southern Minnesota. We’ll top out in the lower 30s once again, with 40 degrees possible in the snow-free areas of southern Minnesota.

Forecast high temperatures Thursday
Forecast high temperatures Thursday.

Note that there’s still plenty of snow cover to play in across northern Minnesota. The National Oceanic and Atmospheric Administration’s snow cover map shows 30 to 40 inches on the ground in the Sawtooth Mountains above Lake Superior.

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Snow cover across Minnesota
Snow cover across Minnesota Wednesday.
NOAA / National Operational Hydrologic Remote Sensing Center

Friday brings snow basically south and west of Brainerd in central Minnesota to the eastern Twin Cities line. Check out my post from earlier Wednesday for details on Friday’s winter storm watch and likely snowfall totals.

Polar vortex in late January?

It’s a question we ask every year. Will we get a polar vortex outbreak this winter?

The latest medium-range maps suggest a possible polar vortex-style outbreak as we move toward the last week of January.

Jet stream forecasts for the last week of January hint at a chunk of the polar vortex spinning through the Great Lakes, with Minnesota under frigid northwest flow pushing in an air mass originating from the Arctic Circle.

Upper air forecast map for 6 pm January 26
Upper air forecast map for 6 p.m. Jan. 26.

It’s still too early for a high degree of confidence in the magnitude and duration of a possible subzero cold wave.

This may be overdone, but NOAA’s Global Forecast System model pushes pulses of subzero air with minus 20s and minus 30 across Minnesota as we move into the last week of January.

NOAA GFS temperature forecast
NOAA GFS temperature forecast Jan. 24-28.
NOAA, via tropical tidbits

It remains to be seen if we’ll get the brunt of a full-fledged polar vortex outbreak the last week of January, but the odds seem to be growing.

Stay tuned.