A frigid airmass will plunge south from northern Canada into the upper Midwest and western Great Lakes this weekend as part of the polar vortex shifts south-southeast. Temperatures at the 500mb level near the upper low are expected to hit around -40°C, which is remarkable. While we don’t live at 500mb (16,000-20,000 feet), surface temperatures will also take a significant dive, with highs only reaching the 20s to around 30 in northeast Minnesota and northwest Wisconsin, and lows dropping into the teens and 20s, with some spots possibly hitting single digits. Considering that normal highs in early November range from the upper 30s to lower 40s, and lows typically stay in the 20s, this cold spell is going to be quite noteworthy for this time of year.
While accumulating snow is unlikely in most of the Northland this weekend, the arrival of cold air combined with a strong upper low and trough moving through the area will likely bring occasional snow showers on Saturday and Sunday, with a light coating of accumulation possible in some spots.
Lake effect snow showers are expected to develop along the South Shore of Lake Superior in northern Wisconsin, with several inches of snow accumulation likely, particularly from Sunday into early Monday.
Another fast-moving system is expected to move east from the northern Plains on Thursday. Similar to the one on Tuesday night, this system will likely bring precipitation, primarily to northern Minnesota and the Arrowhead region, from mid to late Thursday afternoon into Friday morning.
The approaching system is expected to bring colder air, likely turning rain into snow Thursday night in far northern Minnesota, with lingering rain and snow showers persisting into Friday.
Note: Rain showers might occur in Duluth from mid to late afternoon on Thursday through Thursday evening, with a chance of a few rain or snow showers on Friday. No snow accumulation is expected in Duluth out of this system.
NAM 3km model simulated radar forecast valid 12 PM Thursday to 6 AM Friday.
Rain (green)
Snow (blue)
Here is my snowfall forecast for Thursday night through Friday morning, ending at 7 AM on Friday.
Less than 1 inch of snow for most in far northern Minnesota, but a small area in the Arrowhead, inland from Lake Superior in the higher terrain, could see around 1 to 2 inches of snow.
Precipitation totals on Thursday night are expected to be similar to those from Tuesday night, with higher amounts concentrated in far northern Minnesota and the Arrowhead, where 0.1 to 0.25 inches may fall. Much lower amounts are anticipated further south, ranging from just a trace to about 0.05 inches.
