Sandy is number 18 on a list of only 21 potential tropical cyclone names.
In 1978, the World Meteorological Organization divided the planet into six regions based on their shared weather patterns. The regions then decided for themselves a list of human names -- easily recognizable, culturally sensible -- to give to the tropical cyclones that would come crashing through their waters and lands. The Atlantic region, for its cyclone list, uses a rotating selection of names determined by the 25 nations that region encompasses in North America, South America, and the Caribbean: Together, those countries created a list of easy-to-pronounce, inoffensive names that would recycle every six years. Each list contains 21 potential names -- one for each letter in the alphabet, minus the rare letters of Q, U, X, Y, and Z. And those are used in alphabetical order, from Alberto down to William.
For 2012, "Sandy" is the 18th on the Atlantic region's list of potential tropical cyclone names. There are only three more to go in the entire list of 21. Which means that we're getting to the bottom of the barrel, with an entire month left to go in the Atlantic's the six-month-long hurricane season.
This is unusual; the average number of named tropic cyclones each season is 10.1. But it also means that the alphabet, that quintessentially human technology, could be yet another thing being displaced by nature each hurricane season. As we may see an increasing number of tropical cyclones in the Atlantic region each year, 21 letters -- 21 names -- might not be enough.