NOAA (National Oceanic & Atmospheric Administration) is the "official" source of all things related to hurricanes and here is what they say: http://www.aoml.noaa.gov/hrd/tcfaq/B7.html Since 1978, the United Nations' World Meteorological Organization, a group representing some 120 different countries, has used pre-determined lists of names for tropical storms for each ocean basin of the world. The Atlantic basin, which falls under Regional Association IV, has a six year supply of names with 21 names for each year. Why 21 names? Well, the letters Q, U, X, Y and Z are not used because names beginning with those letters are in short supply (you would need at least 3 male and 3 female names for each letter, plus a back-up supply for those retired). Think about it; how many men and women do you know whose names begin with these letters? For more information on hurricanes: http://www.nhc.noaa.gov/