Sometimes we focus too much on the Saffir-Simpson Hurricane Wind Scale (SSHWS) category. The SSHWS category is based on the maximum sustained wind speed, i.e., intensity. But there is often not a good correlation between the intensity and the size. For example, Andrew was a small but powerful Category 5 hurricane when it hit South Florida in 1992. Alex is currently (as of the 5 pm EDT Wednesday June 30, 2010 advisory) a Category 1 hurricane but it has a very large wind field with the tropical storm force winds extending out over 200 miles from the center (yellow area in figure below).
Track and intensity are important but don’t forget that size is important as well. The size obviously affects the distribution of impacts from storm surge, wind, rainfall and tornadoes. There is also considerable uncertainty in forecasting how the size of a tropical cyclone changes with time just as there is uncertainty in forecasting track and intensity.