We haven’t been getting snow dumped on us and it’s kind of disappointing. Lutsen, the downhill ski hill in our area, is open but had to make most of their snow. I’m sure they would appreciate four feet of the real stuff right about now. Cross-country skiers are biting at the chomp to hit the trails, including me, but it’s going to take a bunch of snow before the trails will open. Why aren’t we receiving lake effect snowfall? This article does a great job of explaining the process and if I had to guess at the reason we’re not getting big snowfall right now I would say it’s because there isn’t a big difference between the temperature of the water and the air on the North Shore. What do you think?
Science behind the lake effect
It’s no doubt that parts of the area are going to be dealing with an intense wintry blast over the next several days causing many headaches. There are other parts of the Great Lakes region, though, that will have it worse.
One key ingredient to lake effect snow is something called fetch. Fetch is the distance wind travels over water. The longer the fetch, the more intense the snow bands.
Since the prevailing wind over this part of the country is usually west to east, the fetch over Lake Michigan is relatively small, although still significant enough to create lake effect snow.
However, Lake Erie and Ontario are oriented more west to east so the prevailing wind matches up with the longest axis of both of those lakes resulting in much longer fetch. It’s no surprise that because of this, parts of northwest Pennsylvania and New York are going to be measuring snow in feet!
What about Lake Superior? The west to east distance is even greater than that of Erie or Ontario. Lake Superior is a much colder lake so the difference in air/lake temperature is never as great as it is on Erie and Ontario. The greater the temperature difference between air and water, the greater the instability, and as a result, stronger snow bands develop.
With a north wind Lake Michigan can really produce intense snow bands because the wind will travel along Lake Michigan’s longest axis which is a north to south distance of just over 300 miles. This is what generates major lake effect snow events in areas like LaPorte county. Due north winds are far more uncommon, however, than a west wind, since west is prevailing across this part of the country.
Another reason the eastern lakes have enhanced snowfall is because of the very hilly terrain across New York and Pennsylvania. This terrain causes the air to lift (called orographic lift) which results in heavier snow. Northern parts of Michigan, especially the UP, often see enhanced lake effect snow due to the higher terrain in places like the Porcupine Mountains.