A deadly tornado outbreak in Iowa spawned the farthest north EF4 tornado recorded so early in the year in US history, after close analysis from meteorologists on Monday. A team of meteorologists from NWS Des Moines confirmed wind speeds up to 170mph over a path length of nearly 70 miles through the southern suburbs of Des Moines, Iowa.
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.
In fact, March is the month that has warmed the most in the US over the past 75 years. Large parts of the central and western US, including Iowa, have warmed more than 4 degrees Fahrenheit during March in that amount of time. 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.