John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.
Where and when you'll normally encounter the most violent twisters—mapped.
It's black and thundering out, with rain slashing at the windows and wind bashing the door like an enraged buffalo. Is this just a bad storm, or is it an incoming tornado about to make your life hell?
Staying on top of weather alerts always helps with that question. But for folks who want to know the odds ahead of time, check out this great map from U.S. Tornadoes. Using data from the Storm Prediction Center, it shows which month of the year every county in the contiguous United States hits its average peak tornado season. (Larger, interactive version here.)
Pick a month and you'll see, highlighted in white boxes, the places that normally encounter the most violent, swirling funnels at that time. Here's April, for instance—cities right now in their historical tornadic highs include Dallas; Little Rock, Arkansas; and Jackson, Mississippi.
Though tornadoes can strike almost anywhere, anytime, they tend to follow a migratory cycle. The U.S. Tornadoes crew explains more:
As we've shown in a number of other articles, tornadoes are like snowbirds—they winter in the South. Even there, cool and dry is the name of the game more often than not in the weeks around the new year when tornado tallies reach their minimum. Cold-season tornadoes are generally limited, but larger events happen.
Moving out of winter, we typically see tornadoes move back north and northwest through the Mid-South and Southeast during early spring, then into the Midwest and Plains heading into summer. The main tornado zone ultimately reaches the U.S./Canada border area by July or so, before crashing back southward (with occasional outbursts) during fall.
Tornadoes' favorite stomping ground in the country's midsection—home to the screamin' Tornado and Dixie alleys—is illustrated in this other map, with solid-colored counties racking up an average of more than 25 twisters that month. The summertime hot spots in Florida, for what it's worth, are heavily influenced by hurricanes and other powerful sea tempests.
Next month, 'burbs entering their typical annual peak will include Atlanta, Houston, Raleigh, Wichita, and Oklahoma City. Residents who'd rather escape the swirls this time around might consider vacationing in areas with a May average of zero tornadoes, such as Mineral, Nevada (population 4,772); the perpetually moist Whatcom, Washington; and Napa, California—though watch out for those earthquakes.