Hook- or comma-shaped echoes in Doppler radar images suggest that a tornado has formed.

Maps that show weather conditions are valuable to scientists who study the formation of thunderstorms and tornadoes. A series of such maps can show how conditions change both at ground level and high above the ground. Satellite images and Doppler radar displays show almost instantaneously how weather conditions are developing. However, even Doppler radar usually can’t “see” a tornado directly. The tools that scientists and forecasters use can indicate only when conditions may be right for a tornado to develop. The National Weather Service depends on trained tornado spotters to verify whether a tornado has actually formed.

 

Tim Samaras goes to the Internet for data showing where supercell thunderstorms are likely to develop. Still, even after he locates a storm, he relies on his own observations. He studies the shape and movement of a storm. Then, he decides where to position himself and his team for the best chance of deploying probes in the path of a tornado.

Mobile Doppler radar units can be stationed wherever they are needed. These units allow researchers and forecasters to collect tornado data that nonmobile radar could miss.