Possibly the biggest snowstorm in Chicago since this time last year is on its way, and it will make some noise.
WGN Meteorologist Tom Skilling said Thursday afternoon that a "moderate" snowstorm is making it's way to Chicago, and has already dumped on Missouri and Kansas, producing "thundersnow" along the way.
Skilling explained that thundersnow is a thunderstorm within a snow storm, created when "tremendous" amounts of vertical motion occur within it. Additionally, lightning that occurs during a snowstorm is more likely to last longer and have higher power, because the strikes are more likely to be positively charged. In a normal thunderstorm, about 10 percent of strikes are positively charged.
"These are the ones that are more likely to injure or cause damage," he said, adding that there's an equal chance--albeit small--that a person can be struck during a snowstorm as there is that he or she can be struck during a thunderstorm.
Thundersnow isn't all that uncommon, Skilling said. It just seems like it. Snow tends to block out the view of lightning that occurs, and the flakes often muffle the sound of any thunder. He estimates about a quarter to half of all snowstorms have some sort of lightning activity.
Skilling said the storm, which he estimates will dump 3 to 7 inches of snow on the area, will be most intense between 3 a.m. and 5 a.m. Friday morning. Thursday's evening commute will include flurries, but most of the mess will be in the morning, as freezing rain might be thrown into the mix as the morning goes on.
The storm is expected to rival the snow that fell last year on Feb. 24, when Chicago received 3.5 inches of snow.
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