Lake Effect Snow In Action

March 14, 2017: Lake effect snow was the driving force behind last night’s snowfall, and all of the snow that fell in Chicago and southeast Wisconsin recently, resulting in some pretty impressive snow totals.Locations around Chicago saw between 5″ and 10″ of snow, while areas along the Lake Michigan coastline in Wisconsin saw between 1 ft to nearly 2ft of snow!  Snow amounts ranged between 1″ to 3″ Sunday night into Monday in Chicago, with a new 5″ to 7″ falling between Monday night and Tuesday during the lake effect portion.

Here’s a refresher on lake effect snow. You have to have cold, dry air flowing over warm, moist air.

This typically occurs over a large lake, when the air right above the lake waters is warmer and more humid than the air above it.

If the lake is big enough, there’s enough time and space to have the warm, moist air naturally rise very quickly into the cold, dry air. The bigger the temperature difference, the quicker the warmer air can rise, cool, and condense into clouds and showers. The humid lake air provides plenty of “fuel” to create snow.

At that point, you have intense snow showers forming, then falling over areas near the coastline, generally following the air flow off of the lake. These intense showers aren’t very wide, so snow amounts can jump quickly over a short area.

In this week’s example, snow amounts jumped 5″ or so only over a 15 mile span. This is especially hazardous for drivers- one minute you have clear to slightly snow roads, then next instance you can’t see because of the intense showers, and the roads become snow-covered and very slippery very quickly. Pileups can occur easily in these rapidly changing conditions.

The brief round of lake effect snow blowing in from Milwaukee Monday night added another 1″ to Rockford’s total ,bringing a lot of our area up to 4″ or more for total snowfall.

This is the most snow the area has received at one time since December.



Posted under weather

This post was written by Alex Kirchner on March 14, 2017

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