Here's the Tribune's weather infographic for today:
The warmer-than-normal temperature formerly over Alaska has now swung around into the arctic, dragged by a persistent high pressure over the pole. That's pushing cold air down into the Prairie Provinces and the upper Midwest. Meanwhile, warmer-than-normal temperatures over the south-eastern U.S. and Caribbean is dragging moisture right over the lower Midwest.
Consequence: it's -12°C here right now, and in 36 hours we'll have 250 mm of snow.
We're getting a real winter this year. W00t. :/