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.
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:
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.
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.
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.
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.
^Was deliberately left unnamed to avoid any confusion as the news media was focused on the Perfect Storm and was expected to be short-lived and primarily of concern to maritime interests.[6]
^ abSubtropical storms were not given names prior to 2002. However, since this system was recognized post-operationally it is included in this list.
^Advisories were not issued on this system during August/September 2011 because of the intermittent nature of the convection and the somewhat frontal nature of the satellite presentation.[8]
^This system was upgraded from a tropical depression to a tropical storm after a letter from a ship called the Golden State prompted a re evaluation of the system.[9]
^This system was upgraded from a tropical depression to a tropical storm after a ship called the Richfield reported sustained winds of 115 km/h (70 mph).[9]
^This system was not named or numbered as a tropical cyclone operationally, but has been recognized as an unnamed tropical storm since.[10][11]
^Was upgraded from a tropical depression to a tropical storm after the United States Coast Guard relayed ship reports to the National Hurricane Center, that suggested the cyclone was a tropical storm.[12]
^Was upgraded from a tropical depression to a tropical storm after European Space Agency's Advanced Scatterometer (ASCAT) suggested that the cyclone was a tropical storm.[13]
^Was operationally classified as a depression by both the JTWC and PAGASA, the latter of which named the system Ningning. However, it was later determined by JTWC that the system reached tropical storm intensity.
^Could not be named during February 1997 as it had developed into a tropical cyclone within the subtropic region of the Southern Pacific.[4][5]
^ abRSMC Nadi — Tropical Cyclone Centre; TCWC Brisbane; TCWC Wellington (May 22, 2009). "RSMC Nadi — Tropical Cyclone Centre Best Track Data for 1996/97 Cyclone Season". Fiji Meteorological Service, Meteorological Service of New Zealand Limited, Australian Bureau of Meteorology. United States: International Best Track Archive for Climate Stewardship. Retrieved January 31, 2013.
^ ab"Matt Megan's World". The Manawatu Standard. Palmerston North, New Zealand. April 2, 1997. p. 3. – via Lexis Nexis (subscription required)
^Blake, Eric S; Kimberlain, Todd B; National Hurricane Center (December 2, 2011). Unnamed Tropical Storm: September 1 - 2, 2011(PDF) (Tropical Cyclone Report). United States National Oceanic and Atmospheric Administration's National Weather Service. p. 2. Archived(PDF) from the original on August 5, 2013. Retrieved August 5, 2013.
^ abBenkman, Walter E (1963). Rosendal, Hans E (ed.). Tropical Cyclones in the Eastern North Pacific, 1962 (Mariners Weather Log: Volume 7 Issue 2: March 1963). United States National Oceanic and Atmospheric Administration. pp. 46–49. ISSN0025-3367. OCLC648466886.
^Landsea, Christopher W; Dorst, Neal M (June 1, 2014). "Subject: Tropical Cyclone Names: B1) How are tropical cyclones named?". Tropical Cyclone Frequently Asked Question. United States National Oceanic and Atmospheric Administration's Hurricane Research Division. Archived from the original on December 10, 2018. Retrieved May 19, 2017.
