The United States has a hybrid, almost cyborg method for predicting tornadoes. For decades, meteorologists have been able to detect likely tornadoes remotely by looking for a hook shape on weather radar. But in the past three decades, there have been two major steps forward. First, forecasters can now detect wind speed and direction via Doppler radar, allowing them to identify centers of circulation in storms. Second, they can use reflective radar to look at the presence of objects in the atmosphere that are neither water nor cloud: debris. This technique, made available just in the past few years, lets them confirm the existence of a tornado remotely, by looking for debris lofted high in the sky.
But the service still relies on networks of in-person spotters, first formed in the 1940s as protection for military assets, to confirm the existence of a single tornado. (An earlier Army experiment with tornado spotters and forecasts ended in 1886; a Signal Corps officer had barred the use of the word tornado in the warnings, fearing that it might incite public panic.) On Tuesday, as a mile-wide EF-4 tornado cut across the Kansas City metropolitan area, in-person spotters could affirm its existence in addition to radar.
According to a preliminary report, nobody died in the tornado, though 18 people were injured. If that number holds, it’s “absolutely phenomenal,” Patrick Marsh, a forecaster at the Storm Prediction Center, told me.
This week is the biggest outbreak of tornadoes since the spring of 2011, when hundreds of storms wracked the Plains, killing more than 550 Americans. The death toll was so high, and the damage so awful, that the National Weather Service changed how it communicates severe weather in response. The service now favors direct, plainspoken, and nonscientific language when warning of an incoming tornado, hurricane, or other disaster. On Tuesday, for instance, National Weather Service forecasters explicitly told media outlets in Kansas City to use the strongest language possible when discussing the danger of the massive tornado.
Forecasters’ thinking on the benefits of direct communication has evolved dramatically over time. A century ago, the Weather Bureau, then run by the Department of Agriculture, prohibited its forecasters from mentioning tornadoes to the public at all; in the most dangerous circumstances, they could warn instead of “destructive local storms.” During the decades this ban held, from the early 1900s to the 1950s, research into tornadoes and their formation withered.
The success of the military’s spotter network and its forecasts began to dissolve the U.S. government’s official resistance to talking about tornadoes. In 1948, two military weathermen successfully forecast a tornado in the vicinity of Tinker Air Force Base; the military also developed a habit of leaking tornado forecasts to the public. At the same time, radar was being turned from military to meteorological uses, increasing both the accuracy and utility of tornado warnings. In July 1950, the U.S. Weather Bureau changed its policy. With routine forecasting and directed research, tornado warnings have become reliable and specific enough to create a life-saving buffer for people in their paths.