Lake Effect Snow – Geography Realm

Lakes large enough can have a dramatic impact on snow production and cause an extreme snowfall event.

This phenomenon is known as “lake effect snow” (also spelled lake effect snow).

Lake effect snow occurs when cold, dry air flows over a large lake. The airflow causes evaporation from the warmer water to rise into the colder air. While the now water-rich and warmer air flows on land, it cools down and the water falls to the ground as snow.

How the lake effect produces so much snow

Lake effect snow requires a large difference between the cold, dry air sweeping across the lake and the warmth of the body of water. A temperature difference of 14 degrees Celsius or more creates conditions that can fuel large snow deposits.

A diagram showing how lake effect snow is formed, with blue arrows for cold air and red arrows for warmer air as they flow across a lake and snow is falling on the other side of the lake.
The lake snow effect occurs when cold, dry air flows over a large lake with much warmer water temperatures, causing snow to fall downwind of the lake. Diagram: Caitlin Dempsey.

Other factors that affect snowfall are the length of the lake over which the air flows and the speed at which the air flows. The longer the path of the air across the lake, the more the water is loaded with water moisture through evaporation. Faster air will hold less water moisture than a slower moving air stream.

The result is the formation of heavy snow bands downwind of the lake.

The Great Lakes and the lake effect snow

One part of the United States where lake-effect snow is common is the Great Lakes Region.

Cold winds come in from Canada and sweep across the wide open waters of the Great Lakes before blanketing the winds with snow along the shores.

Satellite images taken after a lake effect snow event over the Great Lakes show belts of snow on the leeward side of the lakes.

These satellite images, acquired by NASA’s Terra satellite on December 9, 2006, show the aftermath of a lake-snow effect event over the Great Lakes region.

A satellite image shows snow covering land around the Great Lakes.
A lake effect snow event on December 9, 2006 around the Great Lakes. Satellite image: NASA Terra, public domain.

This satellite image taken on March 1, 2022 shows how the area around Lake Erie was covered in snow after a late season lake effect snow event that occurred between February 27 and 29, 2022.

Up to 0.6 meters of snow fell in cities such as Carthage and Croghan in upstate New York. Snow also fell in northwestern Pennsylvania and northern Ohio.

In parts of northwestern New York and Pennsylvania, lake-effect blizzards often cause up to two feet of snow to fall in a 24-hour period.

A satellite image showing snow-covered areas in Ohio, Pennsylvania, and New York south of Lake Erie.
The February 27–29, 2022 lake effect snow event left areas south and southeast of Lake Erie covered in snow. Image: NASA, public domain.

Buffalo, New York is known for receiving a lot of snow each year, due in large part to the lake effect snow phenomenon.

Buffalo averages a little under two feet of snow, 95.4 inches, each year. For the 2021-2022 season, which runs from July to June, Buffalo received 97.4 inches of snow.

Areas in the United States where lake-effect snow is common

In the United States, lake-effect snow is common on the Great Salt Lake in Utah, northern Wisconsin, western Michigan, northwest New York, and northwest Pennsylvania.

Lake-effect snow typically occurs in late fall, when large lakes still store much of the summer heat but colder air descends from the north. Beginning in February, areas such as the Great Lakes begin to experience a reduction in days with a lake-effect snow event.

Lake effect snow around the world

Other areas of the world with large lakes and cold winds, such as the Aral Sea, can experience lake-effect snow events.

This satellite image shows snow deposited on the western edge of the southern part of the South Aral Sea. Cold winds blow from east to west in this region of Central Asia.

Satellite image of the Aral Sea with snow at the top of the image and brown landscape at the bottom.
Snow on the western edge of the Aral Sea after a lake effect snow event. Image: NASA, December 27, 2020, public domain.

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