US big freeze

Americans across all 50 US states are still feeling the cold snap after temperatures plummeted to at least zero degrees Celsius (32 degrees Fahrenheit) on Tuesday, leaving people trapped in their homes and vehicles. Such temperatures are not usually expected until late December and early January.

The unseasonal weather has spread across the whole of North America, while heavy snow prompted a state of emergency in western New York where four people died as a result of a huge storms - one in a car accident and three from heart attacks whilst shoveling snow.

Troops from the National Guard were deployed to help residents cope with the extreme Arctic-born weather, which swept across the Rocky Mountains in northwestern America last week. Driving bans were also implemented in some areas.

Thunder snow

The snowstorms have also brought the unusual phenomenon of "thunder snow" or a lake-effect storm, which is the result of cold air passing over relatively warm water, such as that in Lake Erie in northwestern America.

"Some parts of our country are going to receive a years worth of snowfall in three days," said Erie county executive Mark Poloncarz.

In and around the city of Buffalo in upstate New York, a huge lake-effect snowstorm left behind between 1.2 - 1.5 meters (4-5 feet) of snow in less than 24 hours.

Coldest in 38 years

Snow blown by strong winds also left some motorists stranded in a 6.4-kilometer (4-mile) tailback on a section of the interstate highway near Buffalo for almost 24 hours. Efforts to free vehicles were delayed further after two tractor trailers jack-knifed as they were being moved.

Even the state of Hawaii, known for its warm tropical climate in the North Pacific Ocean, was also bitten by chilling temperatures, the National Weather Service said.

Tuesday morning was reported as the coldest across the country in November since 1976.

ksb/nm (Reuters, AFP, AP)