IT is called a ‘lake-effect’ snowstorm — and it has paralysed cities across the US, with temperatures falling to freezing in all 50 states, including Hawaii. Lake-effect snow is produced during cooler atmospheric conditions when cold winds move across long expanses of warmer lake water, providing energy and picking up water vapour, which freezes and is deposited on the leeward shores.
CNN meteorologist Chad Myers calls it ‘thunder snow’.

“The steam from the lake … (is) still much warmer than the air,” he said.

“The air is in the teens and the water in the 40s. That steam comes up and wants to rise. That rise … creates a thunder storm but it’s so cold it doesn’t rain. It just snows.”

The phenomenon paralysed the upstate New York city of Buffalo yesterday, forcing state police on snowmobiles to deliver blankets to stranded motorists on the main highway across New York State. At least four people were killed in the storm, CNN reports.
One of the storm-related deaths was a vehicle accident, said Peter Anderson, a spokesman for the county executive. Three others were cardiac arrests as a result of shovelling…. see more

source: news.com.au