We may not get the heavy snow dumps like the western shore of our state, but Dexter is still affected by Great Lake effect snow. Here’s how it works and how it affects our area.
Along with mountain areas, parts of the Great Lakes are the snowiest places in the U.S. As the winter months begin, they bring the phenomenon that every Great Lakes resident knows (and either loves or hates): lake effect snow.
Lake effect snow is common across the Great Lakes region during the late fall and winter while the water is still unfrozen and relatively warm. Lake Effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes. As the cold air passes over the unfrozen and relatively warm waters of the Great Lakes, warmth and moisture are transferred into the lowest portion of the atmosphere. The air rises, clouds form and grow into narrow band that drops the moisture downwind producing 2 to 3 inches of snow per hour or more.
This might sound a little confusing — how “warm” lake water could result in cold snow. Well, the warmth from the lakes is only enough to get the moisture from the surface of the lake into the atmosphere. Once the moisture is up in that mass of cold air, it turns into snow and then falls — usually about the time it’s passing over whatever freeway you use for your afternoon commute, especially on the western side of Michigan.
Check out this map of the United States: you’ll notice that things generally get snowier the farther north you go, but that the really dramatic snowfall (average of more than 8 feet annually) occurs in two places: high mountain elevations and land adjacent to the Great Lakes. Many areas in the Great Lakes basin average at least 4 feet annually. You can thank lake effect snow for this.
Notice that the western shore of Lake Michigan and Southeast Michigan/Northwest Ohio are somewhat spared — wind patterns have a lot to do with this. It is not enough to just be next to a Great Lake — the wind has to be blowing your way. But all of Michigan has an average snowfall of at least 4 feet. This is due to the Great Lakes’ effect on our state’s early winter weather patterns.
Wind direction is a key component in determining which areas will receive lake effect snow. Heavy snow may be falling in one location, while the sun may be shining just a mile or two away in either direction. The physical geography of the land and water is also important. National Weather Service meteorologists consider these factors as well as others when forecasting lake effect snow.
The video below shows lake effect snow in action. The black arrows represent wind speed (length) and direction, and the color scale shows snow accumulation. This is model output re-creating a lake effect snow event from December of 2016.
The current weather forecast for Dexter for the upcoming Superbowl weekend is for 1-3 inches of snow but there is no mention of lake effect snow because of the ice coverage of the Great Lakes along with cooler temperatures of exposed water have diminished the impact.