11.   A new surge of arctic chill will sweep from central Canada to the upper Midwest on Monday.

12.   A wintry mix of precipitation will develop in the central Plains as warm, moist air just above the surface overruns a shallow layer of arctic chill.

13.   After frequent Arctic chill this month, the current thaw combined with expected rain is raising concern about ice jam floods on creeks and streams around Pittsburgh.

14.   After an Arctic chill this month, the current thaw combined with rain is raising concern about ice jam floods on creeks and streams.

15.   Brisk west winds will scour out the Arctic chill of recent days, in all but the deepest valleys of Idaho and Montana where some ice is still possible.

16.   Despite the shifting pattern, no major storms or Arctic chill will invade the nation through the end of the week.

17.   During autumn, arctic chill advances south from Canada as warmth clings to the southern United States.

18.   During the autumn, the deepening arctic chill advances southward from Canada as tropical warmth clings to the southernmost United States.

19.   Elsewhere, arctic chill will spill south and east from the Northern Plains into the Great Lakes and Northern New England.

20.   Even though the arctic chill will ease this weekend, an opportunity for heavy snow in Boston may come Tuesday.