A major lake-effect snow event has hit the Great Lakes region of the US, causing intense and paralysing snowfall. It started on Wednesday evening, and will probably carry on until the end of the weekend with the worst-affected places being Buffalo City on the eastern edges of Lake Erie, and areas around Watertown on Lake Ontario.
Lake-effect snow occurs when cold air blows across an unfrozen lake that is relatively warm, heating the cold air from below and creating heavy snow showers. These showers often form in narrow quasi-stationary bands causing significant amounts of snow to fall over a small area. This current event is caused by cold air sourced from Canada, blowing cyclonically around low-pressure located above the Great Lakes, becoming a returning south-westerly or westerly flow depending on location.
