Derechos, or ‘land hurricanes’, are laying siege to the country. Derechos don’t come from the ocean like regular hurricaens but are huge, fast-moving windstorms, accompanied by thunderstorms. Their winds are tossing trees around like confetti, killing people—at least 13 so far—in cars, homes, tents, as well as snapping power lines as if they were toothpicks. Over 3 million people are currently without power as a result of the weekend’s weather.

One derecho formed outside of Chicago on Friday and wreaked havoc from there to Washington, D.C. in just 13 hours. Then the east coast was hit again on Saturday with a second line of violent storms.

Tom Kines, senior meteorologist at AccuWeather.com, described how Friday’s mighty conflagration was set off. “There were a few ingredients that fell into place at the same time. First off, the record heat – it was around 100 F on Friday. Then there was the humidity. On top of that, there was also a small piece of energy in the upper atmosphere. To get a storm like that everything has to be perfect—and on Friday, everything fell into place.” He added, “A lot of us won’t see something like that again in our lifetimes—it was pretty special.”

Sounds reassuring, if only Kines had stopped there, but he continued by saying that, with the unusually hot weather expected to continue for 7 to 10 days, another storm like Friday’s is a possibility. Plus, “if indeed we are seeing global warming, then it will certainly increase the risk of something like this happening again.”