A dangerous type of storm called a derecho hit the Great Lakes area on Monday, with lightning striking Chicago's Willis Tower as heavy clouds hung overhead. So what, exactly, is a derecho? It's a large group of thunderstorms with winds that can grow as strong as 50 to 100 mph, capable of affecting areas several miles wide and more than a hundred miles long. Most common in the Spring and Summer, a derecho reaches a much larger region than a tornado, and it typically leaves far more damage in its wake. Following Monday's storm, several injuries were reported along with two deaths [1], and flood warnings have been issued throughout areas of Illinois, Wisconsin, Indiana, Michigan, and Iowa. Take a look at some of the most shocking Instagram snaps of the storm below.

Source: Instagram user rmhess [2]

Source: Instagram user kirkchi [3]

Source: Instagram user kasper_withakay [4]

Source: Instagram user tat_ventures [5]

Source: Instagram user karabeaner17 [6]

Source: Instagram user yilmoose [7]

Source: Instagram user kdloker [8]

Source: Instagram user ericallixrogers [9]

Source: Instagram user rmhess [10]

Source: Instagram user kbucklandphoto [11]

Source: Instagram user thagoods22 [12]

Source: Instagram user hmklein [13]

Source: Instagram user instadurr [14]