A huge storm system traversed the central United States at the end of April, causing weather impacts that included flash floods, severe thunderstorms, tornadoes, hail and strong winds, and even blizzard conditions. While a storms like these are not common, this kind of everything-but-the-kitchen-sink storm does tend to happen a couple of times each spring as drastically different air masses—warm and moist air from the tropics versus drier, still-wintry, air out of Canada—clash over the Great Plains.