More than a million Americans and Canadians are without power on Christmas Day as a severe winter storm hits North America.
A bomb cyclone, when atmospheric pressure drops, is caused by snow, strong winds and cold temperatures.
Nearly 250 million people have been affected and at least 19 deaths have been linked to the storm which has spread more than 2,000 miles (3,200 km) from Quebec to Texas.
Thousands of flights have been cancelled.
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The state of Montana in the western United States has been most affected by the cold, with temperatures dropping to-50F (- 45c).
White-out status has been found in the states of Minnesota, Iowa, Wisconsin and Michigan. In the city of Buffalo in New York state, the US National Weather Service (NWS) recorded “zero mile” visibility.
In the Pacific Northwest, some residents skate on the frozen streets of Seattle and Portland.
In the northeastern New England region of the United States, coastal flooding has hit communities and power lines have collapsed.
Severe restrictions have also been imposed in the South American States of Florida and Georgia.
It is the only city in California where mountain ranges help protect a large number of forests.
The Arctic explosion hit the Canadian provinces of Ontario and Quebec.
Most parts of the country, from British Columbia to Newfoundland, were under a cold and winter storm warning.
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Several deaths related to the storm include road traffic accidents, including a stack of 50 cars in Ohio that killed four motorists. Four others died on the spot in the accident.
Passenger problems across the country were exacerbated by snowplows caused by a shortage of operators, with low pay rates being blamed.
More than 100 daily cold temperature records could be built or broken in the next few days, the NWS said.