The list of unnamed tropical cyclones since naming began includes all tropical cyclones that met the criteria for naming in a basin, but that for whatever reason, did not receive a name. These systems have occurred in all basins and for various reasons.

Scope, reasons, and naming overview

The unnamed subtropical storm 01L in the north Atlantic in 2023

Naming has been used since the 1950 season. In order to ease communications and advisories,^[1] tropical cyclones are named when, according to the appropriate Regional Specialized Meteorological Center or Tropical Cyclone Warning Center, it has reached tropical storm status. A tropical cyclone with winds of tropical storm intensity or higher goes unnamed when operationally, it is not considered to have met the criteria for naming. Reasons for this include:

• Being missed during a season, usually because of uncertainties in classification in real time. An example of this is the Azores subtropical storm from the 2005 Atlantic hurricane season.^[2]
• Disagreements between warning centre and naming centres over intensity of a cyclone. An example of this is Tropical Storm 06W from the 1995 Pacific typhoon season.^[3]
• Formation of a cyclone in an area where no official agency is responsible for naming. An example of this is Tropical Cyclone 29P from the 1996–97 South Pacific cyclone season.^[4][5]
• Intentionally left unnamed to avoid confusion. An example of this is the Perfect Storm from the 1991 Atlantic hurricane season.^[6]
• Post-operational upgrading. An example of this is Tropical Storm One-E from the 1996 Pacific hurricane season.^[7]

North Atlantic Ocean

Only unnamed subtropical cyclones that could have been named are included. This excludes several that existed, but that were unnamed because subtropical cyclones were not named when they existed.

South Atlantic Ocean

The South Atlantic is not officially classified as a tropical cyclone basin by the World Meteorological Organization and does not have a designated regional specialized meteorological center (RSMC) that gives official names to tropical cyclones. Despite this, in 2011, the Hydrographic Center of the Brazilian Navy began giving unofficial names to tropical and subtropical cyclones in the south Atlantic. Prior to that, a few systems in the south Atlantic were given names.

There has been one system, Tropical Storm 01Q in 2021, that was monitored and designated 01Q by the National Oceanic and Atmospheric Administration (NOAA). However, the Brazilian Navy did not recognize the system as a tropical cyclone and it remains unnamed.

Eastern and Central North Pacific Ocean

The unnamed tropical storm 07E in 2020

Naming began in 1960. Before 1960, a few systems in the central Pacific basin were given names, generally in an ad hoc manner.

Western North Pacific Ocean

The unnamed tropical storm 35W in 1996

The official practice of tropical cyclone naming started in 1945 within the western north Pacific.^[14][15] Due to differences in wind speed criteria between the Japan Meteorological Agency and the Joint Typhoon Warning Center, a system will sometimes be considered a tropical storm by the JTWC but only a depression by the JMA, or vice versa. This results in several apparent unnamed systems. Prior to 2000, the JTWC was responsible for tropical cyclone naming, with the JMA assuming responsibility for naming from 2000 and beyond. Due to this, unnamed cyclones that met the JMA's tropical storm criteria but not those of the JTWC prior to 2000 are excluded. Likewise, systems that met the JTWC's tropical storm criteria but not those of the JMA from 2000 to present are also excluded.

North Indian Ocean

Due to differences in wind speed criteria between the India Meteorological Department and the Joint Typhoon Warning Center, a system will sometimes be considered a tropical storm by the JTWC but only a depression by the IMD. This results in several apparent unnamed systems. Because the IMD is responsible for naming, unnamed cyclones that met the JTWC's tropical storm criteria but not those of the IMD are excluded.

Naming has taken place since mid-2003.

There have been no unnamed tropical cyclones using the India Meteorological Department's criteria. One system, 2007's Yemyin, was upgraded after the fact and retroactively named.^[16]

South-West Indian Ocean

The unnamed subtropical depression 11R during the 2000–01 season

Tropical cyclones have been named within this basin since 1960, with any tropical or subtropical depressions that RSMC La Réunion analyze as having 10-minute sustained windspeeds of at least 65 km/h, 40 mph being named. However, unlike other basins RSMC La Réunion does not name tropical depressions, as they delegate the rights to name tropical cyclones to the subregional tropical cyclone warning centers in Mauritius or Madagascar depending on whether the system is located east or west of the 55th meridian east.

Australian region

The unnamed cyclone 22U during the 2016–17 season

South Pacific Ocean

The unnamed cyclone 29P during the 1996–97 season

Notes

References

Unless otherwise indicated, all storms come from the following datasets from the Regional Specialized Meteorological Center:

• Atlantic: ^[21]
• Western north Pacific: "RSMC Best Track Data (Text)". Japan Meteorological Agency. Archived from the original on 2013-06-25. Retrieved 2008-06-21.
• Northern Indian, western north Pacific, Southern Hemisphere: "JTWC Tropical Cyclone Best Track Data Site". Joint Typhoon Warning Center. 2007-08-09. Retrieved 2008-05-21.
• Southwestern Indian Ocean: "Untitled". Météo-France. Archived from the original on 2008-04-21. Retrieved 2008-06-21.

External links

• Unisys Weather Data