The Northern Tier is in the midst of arctic wave 2 of 3 with the best saved till last this weekend.

Ice covered barge enters Duluth ship canal yesterday morning.

With a ridge position near or over Alaska and a low containing a piece of the polar vortex on the west shore of Hudson Bay, waves of frigid air have been diving down the spine North America.

The first wave brought Casper, Wyoming’s coldest low (-33) in 25 years.

This morning was bitterly cold and coldest of the season for most Midwestern cities with Chicago dropping below 0 for the first time in 11 months.

Here’s today’s 500mb height anomaly

500mb temps measured a rare -52C over northern Quebec this morning.

This morning’s Midwest lows.

Lake Michigan seen steaming this morning.

This morning saw Great Falls, MT drop below 0 for an 11th straight morning. Longest streak since 1996.

12pm temps

Current wind chill.

Tonight should be the coldest of the season for the Northeast and Big Cities.

Temps lift through the night tonight as a swath of snow spreads across the Northern Tier Friday into Saturday.

This is followed by even colder air during the weekend.

Note the weather channel has a sub-zero high for Chicago Sunday. Even a high below 10 would be the first before Christmas since 1995 but a high below 0 would be the first since 1983.

Minneapolis could see their first December -20s since 1996 and may approach -24 for a low which would be the coldest since January 2004.

Watch this morning’s video.