What is lake-effect snow? Crazy amounts can fall downwind of the Great Lakes
- Lake-effect snow, which can last for only a few minutes to several days, falls from narrow bands of clouds.
- These snows typically occur only in the fall or early winter, before the lakes freeze over.
- The cities of Buffalo, Syracuse and Rochester annually top the nation's list of snowiest big cities.
Locations along the southern and eastern sides of the Great Lakes are known for getting hit by huge 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.
But what, exactly, is lake-effect snow? How does it happen?
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.
Cold air over warm water
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.
WHAT IS A BOMB CYCLONE?:A winter hurricane, explained.
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 24-hour snowfall total of nearly 6½ feet, set on Jan. 11-12, 1997.
And a crazy total of 5 inches of snow was once reported in just 20 minutes in Turin, N.Y. Why crazy? 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."