In the meantime, a weak clipper system will pass mainly to our north on Saturday which will help to set the stage for extreme cold, straight from the North Pole to come roaring in starting Saturday night. Most of the front passes through Sunday leading to dropping temperatures across most of the Midwest during the afternoon. The coldest of the days looks to fall on Monday.
Here are the latest numbers off the 12z European model from early this afternoon. Its nothing new to places such as northern Minnesota, but what is new is the fact the cold will run 100s of miles further south. Wind chills will range from -30 to -55 during much of the time period of Sunday night through Tuesday morning. Highs will struggle to reach single digits below zero all day on Monday leading to possible records. The all time record high minimum is -11 for Chicago, while this model projects a high of -12, a new record, wow!
Here you see a map of 850mb temperatures (about a mile above the surface) showing the extent of the cold. For a simple perspective, the bright pink on the map is usually reserved for the north pole and part of Siberia. In fact this is what we call the "Polar Vortex." Usually this feature sits on the North Pole, spins around the globe and traps such cold in Northern Canada and Russia. However, on Monday it is poised to move south into the United States, and dominate our temperatures for a few days, before sizzling away Wednesday and Thursday!
Now for the maps. Lets start with what will likely be the coldest day for most places, Monday. On the left you see the latest 12z EURO model run displaying what this computer model has for high temperatures on Monday. Much of these are records. And no, these are not wind chills (see below), they are actually HIGH temperatures. With winds in the 10-20mph ranges, wind chills will be substantial, with widespread wind chill warnings likely during this time. Expect multiple schools to shut down as dangerous "feels like" temperatures overspread the Midwest.
Now we have made it to another historic portion of this post. On the right you will see the 12z EURO forecasted low temperatures Monday morning, or Tuesday morning. Many of these numbers are all time record lows! Low temperatures are tougher to forecast this far out, as clear skies and light winds will be the determining factor as to how cold it can get. So the map on the left is one solution as to low temperatures. Be sure to stay tuned for updates, and plan accordingly if you are out and about during this stretch!
Finally, you made it to the piercing wind chill factors. Below is a snapshot of the wind chills Monday morning assuming reasonable wind speeds. In fact, they could be colder with the gusty winds expected. These are serious values, and can cause frost bite in 4-7 minutes! Take precautions.