LUCKY US: Buffalo is notorious for its mountains of snow but Bradford is no stranger to one of the mysterious phenomenon responsible — “lake effect snow.” In this case, of course, Lake Erie snow.
Our resident weatherman, Brad Ottums, owner/operator ofMcKeanweather.com, explains: “Lake effect snow, one of the lovely (?) weather patterns we see all too many times in northwestern Pennsylvania, occurs when a cold W/NW wind blows across the warmer waters of Lake Erie to create snowfall in large amounts.”
As a cold front moves through the region, the colder wind takes the evaporation off of the flat lake surface and forces it onshore. As the wind and moisture hits the land surface, it is forced up into the atmosphere a bit where a cloud cover will form.
As the moisture quickly freezes over land, it becomes heavier than the clouds can hold, and begins to fall as snow to the land surfaces below. This can be an instant transition, where folks along the shoreline sees plenty of snow, or it can take the moisture to travel a ways inland before it begins to fall. Higher elevations will create more snow.
Some of the largest snow totals during a lake-effect snow event are due to “fetch,” the distance rapidly moving cold air travels across the warmer bodies of water.
Certain winds can travel through the upper Great Lakes, say the length of Lake Huron then across Lake Erie and into Western New York and Pennsylvania. Meteorologists term this a Lake Huron/Lake Erie “connection” and those bands of heavy snow can travels hundreds of miles, gathering density as they go.
With Lake Erie being the shallowest and the smallest of the Great Lakes, by Mid-February it is mostly frozen over with a layer of ice, or a “cap” that keeps moisture escaping from the lake to a minimum, helping to reduce lake effect snow through the remainder of the winter and early spring.
Smaller bodies of water can also create a lake-effect-snow event, such as Lake Chautauqua or the Allegheny Reservoir. Given the right wind direction and fetch over the warmer water, lee sides of that wind can accumulate some “extra” snow through a storm.
In early fall and later in the spring, a not-so-talked-about lake-effect rain can materialize, giving the lee ward areas, at the very least, a fine mist.
