US braces for snow storms as 'polar vortex' blankets Midwest
6 January 2014 Last updated at 14:01 GMT
Temperatures in the US are expected to plummet to record lows after a weekend of heavy snowfall across much of the Midwest.
The plunging temperatures result from the polar vortex, an anti-clockwise pool of cold, dense air.
Hazardous conditions in many states have led to cancelled flights and motorists are being warned against venturing out onto the roads.
Mike Wooldridge reports.