Hurricanes follow an alphabetical naming sequence, but the process is governed by international rules. This standardized naming structure helps meteorologists, emergency management officials, and the media communicate clearly about specific storms, reducing confusion when multiple cyclones are active simultaneously. The system assigns a unique and easily recognizable name to every storm that reaches tropical storm strength (39 miles per hour) within a given basin.
The Hurricane Naming System
The naming of tropical cyclones is determined by the World Meteorological Organization (WMO) and follows a strict alphabetical order within a single season. In the Atlantic basin, a list of 21 names is used, beginning with A and progressing through W. The first named storm always starts with A, the second with B, and so on.
The standard alphabetical sequence skips certain letters due to practical considerations. In the Atlantic and Eastern North Pacific basins, the letters Q, U, X, Y, and Z are omitted. This is because there are not enough common names beginning with these letters that are easily recognizable and pronounceable across multiple languages. This leaves the standard list with 21 potential names for a given year.
Since 1979, the system has incorporated a gender alternation pattern to distinguish storms and maintain the sequence. If the first storm of the year is assigned a masculine name, the second will be feminine, and this alternating pattern continues through the entire list. This balance helps in record-keeping and ensures a clear, non-repetitive framework for identifying storms.
The Use of Rotating Lists
The established alphabetical lists are part of a cyclical system designed for long-term use, not generated anew each year. For the Atlantic and Eastern North Pacific basins, six distinct lists are maintained and used in a continuous, six-year rotation. The list of names used in the current year will be recycled and used again in six years, provided no names were permanently removed.
This rotation is an efficient way to manage names without the continuous need to create new ones. The six-year cycle ensures that the names remain standardized and ready for use at the start of each hurricane season.
Different ocean basins around the world operate under different naming conventions. For instance, the Western North Pacific uses a list contributed by various nations, structured more like a sequential roster than a strict alphabetical progression. Names are generally reused unless a particular storm causes such severe devastation that its name is deemed too sensitive to be used again.
Retiring Names of Significant Storms
The six-year rotating system has an exception designed to address public sensitivity and communication clarity following catastrophic events. If a hurricane causes extreme loss of life or extensive property damage, the name is permanently removed, or retired, from the rotating list. This decision is made by the WMO’s Hurricane Committee during its annual meeting.
The rationale for retirement is to prevent the future use of a name that would be confusing due to its association with a past tragedy. Once retired, a replacement name must be selected to take its place on the list for future rotations. The WMO ensures the replacement name maintains the same starting letter and gender as the name it is replacing.
This ensures the alphabetical sequence and the alternating gender pattern of the original list remain intact for the following cycle. For example, Katrina was retired after the devastating 2005 storm and was replaced by Katia on the list used six years later.
When the Alphabet Runs Out
In seasons where the number of named storms exceeds the 21 names on the standard list, a contingency plan is required. Historically, from 2005 through 2020, the WMO used the Greek alphabet as a secondary naming system once the standard list was exhausted. Storms were named Alpha, Beta, Gamma, and so on.
However, the use of the Greek alphabet was retired following the hyperactive 2020 season because the system proved confusing for several reasons. Greek letters created difficulties in communication and record-keeping, especially when trying to discuss multiple storms named after the same Greek letter across different years. Furthermore, the WMO found it challenging to retire a Greek letter name, as retiring Alpha, for instance, would then disrupt the entire secondary sequence.
In response to these issues, the WMO officially adopted a permanent Supplemental List of names in 2021 to replace the Greek alphabet system. This new list contains a pre-selected set of names used sequentially once the standard alphabetical list is exhausted. This change ensures that all storms, even in exceptionally busy seasons, receive a proper name that can be easily communicated and permanently retired if necessary.