The biggest lake-effect snow event so far this season will impact the snowbeltsto the lee of the Great Lakes during the period from Sunday through Wednesday.This will be caused by a blocking pattern that will keep the Central andEastern parts of the country in the deep freeze next week.
Lake-effect snowstorms run at full throttle from the second half of Novemberthrough December. That's because the temperature of the Great Lakes isrelatively mild compared to the arctic air masses that cross them. What thisproduces is a very unstable atmosphere. The low levels gain a little heat fromthe lakes, while it remains very cold aloft. This causes large bodies of air torise abruptly, forming clouds and snow.
The snow often falls in narrow bands that are strung out in the direction ofthe wind. Often, some of the worst lake-effect snowstorms hit from bands thatare barely 10 miles wide. The trick is keeping the band over one location for alength of time and, if that happens, you can get tremendous snowfalls. Giventhe most extreme situations, lake-effect storms can generate snowfall at therate of 4 or 5 inches per hour!For certain, some of the snowbelts are going to get really dumped on beginningSunday, and travel through these areas will be bad, if not dangerous.
The graph below is somewhat interesting. It shows that heavy lake-effectsnowstorms are far more likely during late autumn that the middle of winter.
That's because the Great Lakes get colder as time goes on, meaning lessinstability.
Story by AccuWeather.com Senior Meteorologist John Kocet.
