Though tornado forecasting has vastly improved over the past few decades, predicting where a tornado will touch down next is virtually impossible. Meteorologists observe the development of temperature and wind flow patterns in the atmosphere. It is these factors which create moisture, instability, lift, and wind shear needed for ‘tornadic’ thunderstorms to develop. However, forecasting severe weather more than two days in advance is little more than guesswork.

A fleet of mobile radars known as Doppler on Wheels (DOWs) are based around tornado prone areas in America. DOWs record minute details of tornado features, including eyes and inflow jets, and wind speeds on and above ground level. Arguably, the most valuable source of information on tornado science and behaviour comes from grass-roots level.

A network of storm chasers and tornado watchers across the United States compile data on tornadoes as they happen. This can sometimes be a very dangerous task. Spotters feed live information to America’s National Weather Service as the tornados develop. This can often mean being what normal people would regard as suicidally close to a twister.

Tornado Alley

Tornadoes affect every state in the US. However, the bulk of them are concentrated in the wide flat expanse of land between the Rocky Mountains in the west, and the Mississippi River in the east. This is known as Tornado Alley – home to some of the most extreme weather phenomena on earth.

The reasons for this are both geographic and climactic. Tornadoes are more common here in the central plains because warm, humid air from the Gulf of Mexico collides with cooler, drier air coming down from Canada. These converging weather fronts create the huge storm clouds that sometimes generate tornadoes. Since Tornado Alley lies isolated from the influences of both Atlantic and Pacific Ocean storms, the unique conditions necessary for tornadoes to form occur more often here than anywhere else.