The six lists are used in rotation and the 2022 list will be used again in 2028.
The list of hurricane names covers only 21 letters of the alphabet as it is difficult to find six suitable names (one for each of the 6 rotating lists) starting with Q, U, X, Y and Z. In the interests of safety, the name must be instantly recognizable. In addition, English, French and Spanish names are used in balance on the list in order to reflect the geographical coverage of Atlantic and Caribbean storms. The list is also gender balanced and respectful of societal sensitivities.
Until 2020, when a very active hurricane season occurred and the list was exhausted, the Greek alphabet was used (Alpha, Beta, Gamma, Delta, Epsilon, Zeta, Eta, Theta, etc). This has occurred twice. The first time was in 2005 - a record-breaking year with several devastating hurricanes including Katrina, Rita and Wilma, whose names were all retired - when six names from the Greek alphabet were used. The second was in 2020 - a new new-record-breaking year with 30 named tropical storms of which nine names from the Greek alphabet, including the devastating hurricanes Eta and Iota.
Starting 2021, in lieu of the Greek alphabet, the lists of supplemental tropical cyclones names will be used.
A name can be retired or withdrawn from the active list at the request of any Member State if a tropical cyclone by that name acquires special notoriety because of the human casualties and damage incurred. The decision to withdraw or retire a name is reached by consensus (or majority vote) during the WMO Regional Association IV Hurricane Committee session that immediately follows the season in question.
Background information regarding the use of the Greek alphabet
The WMO Regional Association IV Hurricane Committee annual session in 2006 discussed the use of the Greek alphabet for hurricane naming, and whether a Greek alphabet name should be retired as done for a regular name when it meets the criteria for retirement. The Committee felt that the use of the Greek alphabet was not expected to be frequent enough to warrant any change in the existing naming procedure for the foreseeable future and therefore decided that the naming system would remain unchanged and that the Greek alphabet would continue to be used.
In this connection, the Committee also agreed that it was not practical to “retire into hurricane history” a letter in the Greek alphabet. Therefore, if a significant storm designated by a letter of the Greek alphabet, in either the Atlantic or eastern North Pacific Basin, is “retired”, the year of occurrence and other details would be included.
However, after the record-breaking 2020 season, the WMO Regional Association IV Hurricane Committee annual session in 2021, decided to end the use of the Greek alphabet and instead, established two lists of supplemental tropical cyclone names, one of the Atlantic, one for the Pacific.