More than 30 million people, roughly 10% of the U.S. population, now call the Great Lakes region their home — a place where all four seasons occur with extreme weather at times. One of the most intense seasons is winter, especially along the shores of these magnificent lakes.
Lake-effect snow is nothing new to the people who live along these lakes. It is a term used frequently by meteorologists, especially between the months of November and February.
Lake-effect snow is created when cold air rushes across the relatively warmer waters of the lakes. As this occurs, warmth and moisture from the lake are transferred into the lower layers of the atmosphere. This now warmer and wetter air mass will begin to rise. As it rises and moves away from the lake it will cool and condense into ice crystals known as snow. Snow bands created by this process could lead to intense, narrow strips of snow that could potentially produce 2 to 3 inches of snow per hour or more.
Wind direction plays a key role in where these lake-effect snow bands develop. Often times heavy snow will be falling in one location, but only a few miles away in either direction there is no snow at all and the sun is shining.
Lake-effect snow bands can sometimes reach to the Miami Valley. While they can be dangerous, more times than not snow squall events, created by the moisture from the lakes, lead to bigger problems. Sometimes, these quick bursts of snow can lead to whiteout conditions and treacherous travel. Snow squalls have been known to be deadly with multi-vehicle pileups on the expressway.
According to NOAA, as of January 18, 2020, only 9.4 percent of the lake was covered in ice. That’s important to note because more ice means a lesser chance for lake-effect snow. Of course, on the flip side, the lower the ice cover, the greater the risk for big lake-effect snow events or at least a higher number of snow events in general.
These vast bodies of water are critical to winter forecast in the Great Lakes, region but have you ever thought of how they were formed?
Around 10,000 to 12,000 years ago, at the end of the last glacial period, a massive sheet of glacial ice receded away from the northern United States. What was once covered by ice now revealed deep, cavernous rivers and basins. Over time, these carved out pieces of land would be filled with fresh water from the glacier itself as it melted away, and are now what’s considered the Great Lakes.
These five deep freshwater lakes are located on the U.S. and Canadian border touching Ontario in Canada, plus Michigan, Wisconsin, Minnesota, Illinois, Indiana, Ohio, Pennsylvania and New York in the United States. Lake Superior, Huron, Michigan, Erie and Ontario cover nearly 94,251 square miles and represent the largest surface of freshwater in the world. To give some perspective, that surface area is nearly the same size as the United Kingdom.
So, the next time you hear me say “lake-effect snow,” you’ll not only understand how it forms, but how the Great Lakes came to be.
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