By Jonny Lupsha, Wondrium Staff Writer
A 2,000-mile storm of rain, snow, ice, and winds crippled the United States last week. Thousands of flights were canceled, homes lost heat, and roads iced over in the South, Midwest, and along the Atlantic. So-called “lake-effect snow” exacerbates things.
A winter storm, unofficially named “Landon,” by The Weather Channel, wrought havoc from Austin to Bangor last week. Cities in the Midwest received up to a foot of snow during its first wave, while Massachusetts reported as much as 30 inches. All in all, the snowstorm stretched approximately 2,000 miles, leaving hundreds of thousands without power and blanketing much of the country with dangerous icy conditions.
Wintry weather conditions can quickly turn deadly no matter which area they affect. However, one often overlooked kind of snow—known as lake-effect snow—can be especially precarious. In his video series The Science of Extreme Weather, Professor Eric R. Snodgrass, Director of Undergraduate Studies for the Department of Atmospheric Sciences at the University of Illinois at Urbana-Champaign, explains this curious phenomenon.
That’s So Fetch
Areas downwind of the Great Lakes receive as much as 16 feet of snow per year from the process of lake-effect snow. It all starts with the large bodies of water upwind of them and the high heat capacity of that water.
“The large thermal inertia of the water means that each winter, the water cools at a much slower rate than the land that surrounds it,” Professor Snodgrass said. “This physical property results in a much later freezing date for the water when compared to the nearby land. The lake effect snow occurs as Arctic air flows over the long fetch of unfrozen water.”
The biggest differences between lake-effect snowstorms and regular snowstorms are that lake-effect snow isn’t caused by a low pressure system and it’s always a localized event. Ordinary snowstorms create snowfall for several hours at a time, in periods lasting several days. Lake-effect snow dumps snow for up to 48 straight hours over its localized area.
Types of Lake-Effect Snow
According to Professor Snodgrass, lake-effect snow organizes into separate types, based on the orientation of the wind compared to the shape of the lake from which it originates. The first is called wind-parallel, lake-effect snow bands.
“Wind-parallel bands form when the wind crosses the long axis of the lake in a perpendicular fashion,” he said. “A west or northwest wind will blow perpendicular to the [long axis of Lake Michigan] and create several rows of lake-effect clouds. The clouds appear in rows because of the effects of rising air: When air rises in one location, it must sink in another, so as to fill the void left by the rising air.”
The same winds that blow over the long axis of Lake Michigan, Professor Snodgrass said, run parallel to the long axes of Lake Erie and Lake Ontario, producing a single “shore-parallel band” of snow. Buffalo, New York is often hit by a shore-parallel band.
“Shore-parallel bands of snow are hyperfocused snow machines,” he said. “[In November 2014,] parts of downtown Buffalo spent spent several hours underneath one of these intense shore-parallel bands—five to seven feet of snow piled up, yet the snow band missed part of the city just just a mile or so down the road. There, they received only an inch or two.”
Multi-band, and single-band, lake-effect snow each have very different effects and consequences on their environments.