(NBC News) An icy blast from Canada is plunging deep into the United States, setting up destructive and dangerous scenarios.
The polar vortex is pushing south again, and from Minnesota to Buffalo the thermometer will soon struggle to get above zero.
It's expected to worsen ice jams in already clogged rivers, like the Vermilion in Ohio and the Allegheny in Pennsylvania.
Residents living nearby are already nervous.
The system is expected to bring heavy snow to the Northeast by Friday.
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