The winter of 2021-2022 is now one of the deadliest on record in terms of tornadoes, following a trend that scientists have been tracking in recent years as winter shrinks in duration and more violent storm systems in fall and spring happen more frequently.
Tornadoes require warm, moist air in addition to other meteorological ingredients
and are difficult to predict how they will change in a warming climate
. In recent decades, tornado outbreaks (when 30+ tornadoes happen on the same day) have been getting more frequent, even as total numbers of tornadoes have remained about the same. Tornadoes have also been shifting further northward and eastward as the western megadrought expands into the central United States. This weekend’s tornadoes in Iowa fit all these trends. — Eric Holthaus