The surprising reason lake-effect snow buries cities: It's fluffy

Winter 2024 has made its presence known in December, as locations along the southern and eastern sides of the Great Lakes were hit with colossal amounts of snow.

When snow piles up in places such as Buffalo in western New York or Marquette in the Upper Peninsula of Michigan, people start talking about the lake-effect ‒ and the unthinkable amounts of snow it can produce.

That's in part because lake-effect snow has a low water content, making it light and fluffy — that makes it easier for it to quickly pile up.

According to weather historian Christopher Burt's book "Extreme Weather," extreme lake-effect snows are "normally very fluffy, with snow to water ratios as high as 40 inches of snow to melted precipitation." (Snow usually has a 10-to-1 ratio.)

In addition, Burt said the snow belts around the Great Lakes that get the most eye-popping snowfalls tend to be not right on the lakeshores, but rather places inland 20 or so miles, where hills provide the lift necessary to squeeze moisture from the onshore winds.

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How lake-effect snow forms

Lake-effect snow, which can last for only a few minutes to several days, develops from narrow bands of clouds that form when cold, dry arctic air passes over a large, relatively mild lake.

As the cold air passes over the unfrozen and "warm" waters of the Great Lakes, warmth and moisture are transferred into the lowest portion of the atmosphere, the National Weather Service says. The air rises, and clouds form and grow into narrow bands that produce 2 to 3 inches of snow an hour or more.

Wind direction is also a key component in determining which areas will receive lake-effect snow. Heavy snow may be falling in one spot, while the sun may be shining just a mile or two away in either direction.

These snows typically occur only in the fall or early winter, before the lakes freeze over. (But if the lakes don't freeze, lake-effect snow can occur throughout the winter and into the spring.)

Lake-effect snow records

How snowy? In the lake-effect parts of western New York state, for instance, Buffalo, Syracuse and Rochester annually top the nation's list of snowiest big cities, each averaging more than 8 feet a year because of their proximity to lakes Erie and Ontario.

The three cities vie each winter for the "Golden Snowball," awarded to the region's snowiest city.

Nearly unimaginable snowfalls have occurred in New York, thanks to lake-effect snow: The tiny town of Montague, downwind from Lake Ontario, holds the "unofficial" world record for 24-hour snowfall total ‒ nearly 6½ feet, set on Jan. 11-12, 1997.

And an impressive total of 5 inches of snow was once reported in just 20 minutes in Turin, N.Y. (Typically, a snow total of 2 to 3 inches an hour is considered "heavy.")

Sometimes lake-effect snow clouds develop enough up-and-down motion to create thundersnow – a snowstorm with thunder and lightning.

Though the USA's heaviest lake-effect snow falls around the Great Lakes, it also falls on other places, especially near the Great Salt Lake in Utah.

People who live where lake-effect snow is common take the prodigious snowfalls in stride: As a Syracuse resident was quoted as saying in the book "Lake Effect: Tales of Large Lakes, Arctic Winds and Recurrent Snows": "We have no natural disasters. We never have to worry about hurricanes. Very rarely a flood. I can live with the occasional snowstorm. Then you can get out there and ski."

This article originally appeared on USA TODAY: The surprising reason lake-effect snow buries cities in winter storms