AccuWeather's Bernie Rayno explains the mechanics that goes behind the creation of lake-effect snow as the season begins during the week of Thanksgiving for the Great Lakes region of the U.S.
00:00As we go through November and December, all of a sudden, it's lake effect snow season.
00:07Now, lake effect snow happens when we have the colder air going over the warm water.
00:11And when you have a sufficient temperature difference between the water temperatures of the lake and the temperature at about 5,000 feet, you get lake effect snow.
00:21Usually, you need that difference to be 23 degrees Fahrenheit.
00:24That is, the air at the loft is 23 degrees colder than the warm waters of the lake.
00:31Also, you need cyclonic curvature around the storm to increase the upward motion.
00:36That you need is because it's usually lake effect snow occurring behind the storm, not out ahead of it.
00:43And oftentimes, behind the storm, you have downward motion.
00:45But that cyclonic curvature produces upward motion.
00:49Now, the wind direction is what determines where the lake band set up.
00:55And in this case, we're going to see this first.
00:58More of a westerly wind at first, and then the winds go out of the west-northwest.
01:04So that's why we say the lake effect snow belts that get hit with the westerly wind and then the northwesterly winds are the ones that are going to get the most snow.
01:14All right, lake effect snow begins Wednesday night near the western lakes and then Thursday night across lakes Erie and Ontario.
01:23And boy, oh boy, is the snow going to be coming down heavy as that cold air comes in from the west-northwest here.
01:29In fact, it will resemble a blizzard in those west-northwest snow belts because the winds are going to be quite gusty.
01:36They start Wednesday, Wednesday night, and those winds continue as we head into Thursday and Thursday night.
01:44And of course, with the snow and blowing snow, this is going to resemble a blizzard near the lakes.
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