Ice-breakers deployed to Lake Michigan
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Ice-breakers on Lake Michigan as US weather worsens

Parts of the US are braced for potentially record-breaking low temperatures as a "polar vortex" brings more freezing weather.

Temperatures in the north and central US could feel as low as -51C (-60F) with the effect of wind chill, forecasters say.

ABC News reports that ice-breakers have been deployed to Lake Michigan to clear the way for freighters.

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