NOAA NWS National Hurricane Center – The National Hurricane Center (NHC) determined that a subtropical storm formed in the Atlantic Basin in mid-January 2023.
Through the course of typical re-assessment of weather systems in the National Hurricane Center’s (NHC) area of responsibility, NHC hurricane specialists have determined that an area of low pressure that formed off the northeastern coast of the United States in mid-January should be designated as a subtropical storm.
Specific information on the justification for the subtropical storm designation, as well as the system’s synoptic history and impacts, will be available in a Tropical Cyclone Report, which will likely be issued during the next couple of months.
This subtropical storm is being numbered as the first cyclone of 2023 in the Atlantic basin and will be given AL012023 as its system ID.
As a result, the next system that forms in 2023 in the Atlantic basin will be designated as AL022023, and advisories will be issued in AWIPS bin 2 (e.g., Public Advisories will be issued under AWIPS header TCPAT2 and WMO header WTNT32 KNHC).
If the system begins as a tropical depression, then it would be given the designation ‘TROPICAL DEPRESSION TWO’, and if it becomes a tropical storm, it would be given the name ‘ARLENE’.
National Weather Service policy (through NWS Instruction 10-607, Section 1) allows for marginal subtropical systems to be handled in real-time as non-tropical gale or storm events in NWS High Seas Forecast products. This was the procedure followed for the unnamed subtropical storm in mid-January.
However, the lack of real-time issuance of advisories does not preclude NHC from retroactively designating these systems as subtropical cyclones in post-analysis, if necessary.