The National Hurricane Center (NHC) announced today that a subtropical storm formed well east of the New Jersey shore. The catch is this determination is from a system that formed in January.
“Through the course of typical re-assessment of weather systems in the National Hurricane Center’s 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,” said the NHC in a Public Information Statement released today.
On January 16, images and data collected from NOAA’s GOES-East weather satellite showed what appeared to be a cyclone of some sort formed east of New Jersey. The system blossomed over an unusually warm Gulf Stream which sends warm water up the off-shore waters of the East Coast from the Bahamas. At the time, satellite imagery from the GOES-East satellite showed an eyewall of sorts forming, with satellite estimated wind speeds in the compact storm well over hurricane force.
The typical Atlantic Hurricane Season doesn’t begin until June and runs through November, making any January system a rare one. While rare, they aren’t impossible; there have been three on record, with the last one being Hurricane Alex in January 2016.
To be considered an actual hurricane and earn a name, though, the National Hurricane Center (NHC) must make certain the system meets all criteria for hurricane status, including detailing the type of core the system has and the type of atmospheric structure that exists around and within the storm. When the storm formed, the NHC wasn’t ready to label this as a tropical or subtropical storm.
At the time, the NHC wrote, “A non-tropical low pressure system centered over the northwestern Atlantic Ocean about 300 miles north of Bermuda is producing storm-force winds.” The NHC said added in their Special Tropical Outlook Update, “Although the cyclone is producing some thunderstorm activity near the center, it is embedded in a cold air mass with nearby frontal boundaries. The low is expected to move northeastward today and northward tonight, bringing the system over much colder waters and across Atlantic Canada by early Tuesday. Therefore, it is unlikely that the low will transition to a subtropical or tropical cyclone.”
While the system wasn’t classified right in January, the National Weather Service did issue advisories for it in their High Seas Forecasts. Because it was moving away from land, it was only a threat to shipping interests in the North Atlantic.
While this system is now the first tropical or subtropical system of 2023, it won’t be retroactively named. “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,” said the NHC today in their Public Information Statement.
If the next system of the season 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.”
According to the NHC, 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 National Weather Service High Seas Forecast products. The NHC said, “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 a subtropical cyclones in post-analysis, if necessary,” which is exactly what happened today.