The chilliest air mass of the young winter season is bringing about a widespread case of weather whiplash and leading to areas of significant snow — just in time for Thanksgiving and Black Friday.

A potent and windy storm system is delivering a blizzard to parts of the Great Lakes region as it heads toward southeast Canada through Thursday. In the surrounding areas that will get the brunt of the precipitation — downwind of the lakes — yardsticks will be required to capture the full tallies.

Meanwhile, as most of the eastern two-thirds of the contiguous United States shivers in wintry winds, the Pacific Northwest will be facing its own rough holiday conditions. A storm system arriving there will soak the region through Thanksgiving and Friday, before spreading a new round of wintry condit

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