Polar vortex

• Officials sound alarm as unusual, dangerous phenomenon expected to sweep through Eastern US: 'Coldest ... of the season' - The agency stressed the importance of safety indoors and outdoors and provided several tips.
• Will it snow this week in Westchester, Rockland, Putnam? See forecast - When will it snow again in the Lower Hudson Valley? There may be a slight chance we could see more of the white stuff the week of Dec. 8.
• Triple polar vortex sends temperatures plunging in central and eastern U.S. as 1st Arctic cold blast moves in - The first of three rounds of bitter air has arrived, threatening record lows in cities from the Midwest to the Northeast.
• Triple polar vortex to plunge central and eastern U.S. into Arctic cold through mid-December - The first cold snap is happening this week.
• Weather Words: Sudden Stratospheric Warming - A Sudden Stratospheric Warming Event describes the rapid warming and disruption of the stratospheric polar vortex above the Arctic.
• Think it’s cold now? Just wait for this week’s Arctic blast that’s poised to break records - It’s cold now, but the next punch of Arctic air will take it to another level.