Over 50 people have died and many communities have been destroyed in the past few weeks as tornadoes tore through the southern and central regions of the US. Flights were canceled and millions of people were under tornado watches (The New York Times). Surprisingly, these tornadoes hit Arkansas, Alabama, Mississippi, Tennessee, and Illinois, as opposed to the typical “Tornado Alley” states of Texas, Oklahoma, Kansas, and Nebraska (The Guardian).
Tornadoes form due to instability in the air. Cold, dry air tops warm, moist air and this imbalance causes strong updrafts. Wind shear increases the strength of the updrafts and rotates the air; a tornado is born. Tornadoes originate from thunderstorms and are more likely to form if the storm is a supercell (NOAA). Supercells are severe and last for a long period of time (NOAA), and researchers have found that they will be more frequent this century (AMS). Additionally, atmospheric moisture and instability–two key ingredients for tornadoes–will increase as climate change intensifies. However, scientists are currently unable to predict the effects of climate change on wind shear, another factor in tornado formation, and tornadoes remain hard to forecast. We still do not know enough to establish a clear cause-and-effect relating tornado strength and frequency to climate change (ABC News; The Guardian).
The annual count of tornadoes has remained constant over the past few years, but the tornado alley has shifted eastward, with fewer tornadoes in the central and southern Great Plains and more tornadoes in the Midwest and Southeast (Nature). Because tornadoes are shifting east, they are more likely to hit developed and populated areas of the country, impacting more people’s lives than ever before (The Guardian).