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Great Blizzard of 1978

Historically strong winter storm across central and eastern USA in 1978

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Meteorological synopsis

Late on Tuesday, January 24, 1978, surface maps revealed a moisture-laden Gulf low-pressure system developing over the southern United States, while a separate and unrelated low-pressure system was present over the Upper Midwest. A powerful Arctic jet stream (containing a wind max of 110 knots) surged straight south through the Northern Great Plains while a powerful subtropical jet (containing a wind max of 130 knots) moved south through Arizona, both during the time a huge upper ridge of high pressure forced the Pacific jet north into Northern Canada. These Arctic and subtropical jet streams merged (with maximum winds of 150 knots) which led the deepening Gulf low-pressure system, which had moved over Alabama and Georgia, to undergo explosive cyclogenesis and move rapidly northward towards West Virginia during the evening of January 25 (when record low pressures were logged across parts of the South and Mid-Atlantic). To be classified as undergoing explosive cyclogenesis, a storm's central pressure must drop at least 24 millibars, or an average of 1 millibar per hour, over a 24-hour period; the Great Blizzard dropped by a remarkable 40 millibars in that 24 hours.

The storm initially began as rain, but quickly changed to heavy snow during the predawn hours (as Arctic air deepened ahead of the storm), leading to frequent whiteouts and zero visibility during the day on January 26. As the storm headed for Ohio, it was "of unprecedented magnitude", according to the National Weather Service, which categorized it as a rare severe blizzard, the severest grade of winter storm. Particularly hard hit were Illinois, Indiana, Kentucky, Michigan, Ohio, and southeastern Wisconsin. Muskegon, Michigan, had up to 52 inches of snow in four days due to heavy lake-effect snow squalls after the blizzard began. Winds gusting up to 111 miles per hour (179 km/h) caused drifts that nearly buried some homes. Wind chill values reached −60 °F (−51 °C) across much of Ohio, where 51 of the at least 90 storm-related deaths occurred.

In Canada, the storm caused blizzard conditions across southwestern Ontario. In London, Ontario, 41 centimetres (16 in) of snow fell; the maximum wind-speed was 128 kilometres per hour (80 mph).

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