Via the US National Weather Service's Weather Prediction Center: WPC's Short Range Public Discussion. Click through for a link to graphics.
***Record-breaking cold expected over much of Eastern U.S.***
***Snow and wintry mix with a developing surface low***
***Most of the Western U.S. will have quiet weather***
The coldest weather in years will be making its presence known from the Upper Midwest to the Mid-Atlantic region for the beginning of the work week. The polar vortex, a mid-upper level cyclonic feature normally present over northern Canada, will be displaced unusually far to the south over the northern Great Lakes and southern Ontario.
Owing to the deep layer of the cold air mass, this will provide for an incredibly strong surge of bitterly cold Arctic Air along with gusty winds.
The Upper Midwest will be affected first by Saturday night, and the brutal conditions will continue pushing southeastward to the Ohio Valley and Mid-South by Monday, and to the Northeast and Mid-Atlantic by Tuesday.
Particularly noteworthy will be the extreme wind chills and nearly unheard-of daytime highs that are forecast. A huge expanse of wind chill warnings are in effect from Montana all the way to the central Appalachians, with wind chills on the order of -20 to -50 degrees expected!
Afternoon highs on Monday for parts of the Midwest states and the Ohio Valley will fail to reach zero degrees [Fahrenheit]!
The good news is that it will be a quick event, and moderating temperatures are expected to return by Wednesday.
Ahead of the Arctic blast, a developing surface low along the cold front will result in widespread snow from Missouri to the Ohio Valley and into the Great Lakes. Areas that have persistent snow bands may receive on the order of 8 to 14 inches of snow, with locally higher amounts. Winter storm warnings are in effect as a result.
Along the East Coast, periods of light rain and a very brief period of warmer temperatures can be expected through Sunday night before an incredible drop in temperatures ensues by Monday night.
Elsewhere, with the exception of some orographically enhanced snow showers across the central and northern Rockies, the majority of the Western U.S. can expect relatively pleasant weather conditions through Tuesday.
Eastern Canada has already taken a beating, but here in Vancouver we enjoyed a cold, sunny day. Monday's forecast is a mix of sun and cloud with a high of 4ºC. Then it's rain for the rest of the week.