Hurricane researcher checking a map as he chases Hurricane Floyd. He is in a mobile radar vehicle called Doppler on Wheels (DOW 1). Tracking the development and movement of the hurricane on the ground allows valuable information to be gathered. Radar measurements of rainfall, wind speed and heading are all studied. The data can be used to advise people in the path of the storm of their best course of action. They are also used to help better predict the behaviour of subsequent hurricanes. Floyd hit the southwestern United States on 16th September 1999, and caused over 50 deaths. Photographed in North Carolina, USA.