The shift is serious: Tornado shelters are common in Texas and Oklahoma but less so elsewhere.

Tornado Alley moving eastward is more than a meteorological curiosity. Milder winters mean the unstable air masses that can create supercells may become more likely in March or even earlier in the southeastern U.S. The dry line “can be a boundary for convection-the rising of warm air and sinking of colder air that can fuel storms,” wrote Ernest Agee, professor emeritus of atmospheric science at Purdue University, in the Conversation in 2022.Ĭlimate change may extend the typical tornado season as well. (To the east, thirsty crops such as corn predominate to the west, drought-tolerant wheat prevails.) The line, which for centuries has fallen roughly along the 100th meridian, has moved east by about 140 miles since the late 1800s. The imaginary line runs north from the U.S.-Mexico border up to Canada, dividing the wetter eastern U.S. Research suggests that the so-called dry line is also shifting eastward. Climate change is warming the Gulf of Mexico as well, which can send generous amounts of water vapor into the southeastern U.S. Tornadoes also are more likely to develop when the local atmosphere is unstable, “and warming increases instability,” says Zuohao Cao, a tornado expert at Environment and Climate Change Canada, who co-led a recent study on storm touchdown locations. Supercells tend to form when warm, humid, low-level air interacts with cool, dry, upper-level air, and climate change is generating warmer, moister air.

Why is this shift happening now? Most often tornadoes are created by a supercell-a strong thunderstorm with a rotating updraft of air. with just one tornado and more days when there are multiple tornadoes,” says Naresh Devineni, an associate professor at City University of New York, who co-led a 2021 geographical analysis of large tornado outbreaks. “It looks as if we may be having fewer days in the U.S. And outbreaks may be getting fiercer and more frequent. The swarms are clustering in a tighter geographical area than in the old Tornado Alley, too. Those events happened in just the run-up to peak season in April and May.ĭata gathered in the past two years show that in addition to solo storms, large tornado outbreaks-multiple twisters spawned by a single weather system-are shifting even more definitively to the east. A week later storms in the new tornado alley killed more than 30 people, and another group on April 4 damaged more than 80 structures in Bollinger County, Missouri. A violent twister with wind speeds of 170 miles per hour struck Rolling Fork, Miss., on March 24, killing at least 26 people. Tornado activity in early 2023 epitomized the trend. Huffman ( map) Source: “Examining the Changes in the Spatial Manifestation and the Rate of Arrival of Large Tornado Outbreaks,” by Niloufar Nouri and Naresh Devineni, in Environmental Research Communications, Vol.

Eastward sam