Spring is the most likely time for tornadoes to spin up in the United States; a fact that the people of Oklahoma know only too well. Two weeks ago a devastating tornado swept through Moore, a suburb of Oklahoma, taking twenty-four lives, injuring hundreds, and flattening more than 12,000 homes. Residents had just over thirty minutes warning to try and take shelter from the deadly twister. In tornado terms that was generous: the average lead time is just thirteen minutes. However, an ambitious project, known as VORTEX2, hopes to make major improvements.
In the United States, tornado forecasters have to keep an eye on the 100,000 thunderstorms that form each year. Just 1000 of these (one per cent) form tornadoes, and of those 1000 only one is likely to reach the intensity of the tornado that struck Moore in Oklahoma.
Meteorologists have to rely on radar to identify which storms are spinning, but radar images can't show whether a tornado has reached the ground. During 2009 and 2010, VORTEX2 scientists chased tornadoes across the US, measuring them with an array of mobile radars and weather stations, from every direction. Now the scientists are analysing this data and trying to establish what a twister's early warning signs might be.
With this greater understanding they expect to be able to reduce false alarms from around one in four to less than one in two, and increase the average warning time to more than 20 minutes – vital extra minutes that will save lives.