Lake-effect snow
Lake effect snow is produced in the winter when cold winds move across long expanses of warmer lake water, picking up water vapor which freezes and is deposited on the lee shores. This effect is enhanced when the moving air mass is uplifted by the orographic effect of higher elevations on the downwind shores. This uplifting can produce narrow, but very intense bands of precipitation, which deposit at a rate of many inches of snow per hour.
Cold winds in the winter typically prevail from the west-southwest to the northwest in the North Temperate Zone, producing the most dramatic lake effect snow falls on the northeast to south east shores of the United States' Great Lakes. This lake effect produces a significant difference between the snow fall on the eastern and western shores of the Great Lakes. If the air temperature is not low enough to keep the precipitation frozen, it falls as lake effect rain.
Similar snowfall can occur near large inland bays, where it is known as Bay effect snow. Note that Nor'easters are ocean effect storms produced by offshore lows, which bring moist, unstable air across land areas, often opposite to the usual prevailing winds.
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