'Lake-effect' snow paralyses parts of New York state - and forecasters warn more is on the way

A weather phenomenon known as "lake-effect" snow has paralysed parts of New York state.

Almost two feet of snow fell overnight in parts of western and northern New York, along the eastern end of Lake Erie, with warnings of more to come.

Schools and train stations shut in Buffalo, while numerous flights from the city's airport were cancelled.

The NFL said it would relocate the Buffalo Bills' home game against Cleveland Browns to Detroit.

Orchard Park, where the team plays, was under more than two feet (61 cm) of snow by mid-morning on Friday.

New York governor Kathy Hochul declared a state of emergency in 11 counties.

Driving was banned in Erie County as heavy snow punctuated by thunder and lightning - known as 'thundersnow' - moved into Buffalo.

The most intense snowfall was expected to last into Friday evening, with more falling on Saturday into Sunday.

Some 4.5ft (1.4m) could build up in or near Buffalo, according to the National Weather Service.

Lake-effect snow forms when dry, freezing air picks up moisture and heat as it moves along warmer lake water, according to the National Oceanic and Atmospheric Administration.

It causes some of the lake water to evaporate into the air, making it warmer and wetter.

As the air cools and moves from the lake, it dumps all the moisture on the ground. And when it's cold enough, it results in massive snowfall.