A severe thunderstorm watch covering much of the state of Maine last Monday brought out the typical "this NEVER happens!" commentary, but really, how common are severe weather watches around the United States?

Dozens of National Weather Service offices around the country issued 1,232 severe weather warnings as dangerous storms raked the eastern two-thirds of the United States. The map beautifully illustrates where the worst outbreaks occurred, as well as the general southwest-to-northeast path that the severe storms took.

A butterfly flapping its wings in Brazil may not cause a tornado in Texas, but winds blowing from the south can send moisture from the Gulf of Mexico thousands of miles away into remote sections of northern Canada. The maps that show this atmospheric flow are an awesome testament to the power of the weather.

This was a weather map drawn back on April 18, 1880, showing the weather at 1AM Eastern for every weather station in the United States. Less than 24 hours later, dozens of tornadoes would tear across the central United States, killing over 100 people.

Satellite images over the past few weeks have been anything but boring, and last night's thunderstorms were no exception. A weakening squall line moving through Illinois and Missouri formed into almost a perfect cane shape as the northern end wrapped around a strengthening low west of Chicago.