Updraft® - Minnesota Weather News

Cold nights, light snows; milder air returns later in the week

Some places will get quite cold along the international border

500 height pattern
Mid and upper-level atmospheric pattern across North America
National Oceanic and Atmospheric Administration, via Pivotal Weather

A blocking pattern is forcing cold south, but not quite through Minnesota. Expect some cooler nights and a couple light snows for some. Milder air moves back in by the end of the week.

Greenland blocking pattern

We’re seeing the reemergence of a blocking pattern that was familiar in mid November, the “Greenland block.” This happens when an anomalous ridge of warmth develops through the North Atlantic into Greenland.

Another ridge of warmth pushes the flow of the atmosphere north over Alaska as well and this forces the coldest air over the North Pole into Siberia and North America.

500 set up
Blocking ridge across Greenland and Alaska splitting the cold into Siberia and North America
NOAA, via Pivotal Weather

This pattern has been happening on and off now since the second week of November and we can see its results. 30 day temperature anomalies show the much above normal “hot spots” over Alaska and Greenland, while the west coast into Minnesota have been colder than normal.

30 day temp anomalies
Past 30-day temperature anomalies (difference from normal) across the Northern Hemisphere
WeatherBELL Analytics

The result has created a lot of open water around Utqiagvik (formerly Barrow), Alaska, in the Chukchi sea.

sea ice extent Alaska
Sea ice extent compared to previous years and recent averages near Alaska
NOAA National Snow and Ice Data Center

Recent high temperatures in northern Alaska, above the arctic circle, were in the 30s and even low 40s for many locations!

Alaska high temperatures December 5
Dec. 5 high temperatures around Alaska
National Weather Service

Light snow clippers ride the edge of the cold

The polar vortex remains strong however so far, meaning that while these patterns can temporarily split or stretch the cold, it does regroup again into a more cohesive blob of cold again.

850 T loop
Forecast lower level temperature pattern through Friday across the Northern Hemisphere
NOAA, via Pivotal Weather

The edge of this very cold air will touch the border of Minnesota and Canada early this week. That means while we’ll also see cooler lows, in the single digits Monday and Tuesday nights. Hallock, Roseau, International Falls and other spots in northern and northwestern Minnesota will be close to minus 15 or minus20 Tuesday night.

Riding the edge of this cold air will be a few clipper systems bringing mainly light snows to Minnesota. We can really see this outlined when we compare the midlevel pattern and 72-hour snowfall forecasts:

heights & snow
Upper-level pattern of anomalous cold and warmth with 3-day snowfall totals below
NOAA, via Pivotal Weather

As the cold convergences into a larger area, toward the North Pole again later this week that will allow milder air to return. It looks like southern Minnesota is in for a string of days in the 30s starting Friday.