Lake-effect snow in the USA

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  • Lake-effect snow in the USA
    11.12.2016 18:02

    Parts of the Midwestern and north-eastern states of the USA have been hit by continuous lake-effect snow over the past few days. With generally westerly winds the worst affected areas were those directly east of the Great Lakes, particularly of Lake Erie. For example, Perrysburg, to the east of Lake Erie received 17 inches of snow with snow falling at a rate of up to 2 inches an hour.

    Such incidences of lake-effect snow occur when a cold air mass flows over relatively warm water. The water heats the air directly above the surface, leading to an unstable profile, whereby warm, less dense air near the surface of the water wants to rise above the surrounding colder, denser air. The rising air cools and condenses to form shower clouds and when temperatures are cold enough, snow is produced.

    This effect is regularly seen in the USA in winter, as cold Arctic air flows over the relatively warm Great Lakes. As was the case this week, persistent westerly winds led to continuous bands of heavy snow being driven into the eastern sides of the Great Lakes, while some areas to the west have remained snow free.

    Over the next week the chance of lake effect snow will continue for some as north-westerly winds will bring a plunge of Arctic air across the eastern half of the USA. Maximum temperatures in the Chicago area are expected to be close to just -12C (10F) by Thursday. 

    By: Callum Stewart