Don’t be surprised if you missed it in January. The National Hurricane Center is just now reporting the system as a subtropical storm.
The NHC report released May 11, determined that a mid-January gale off of New England in the Atlantic should be classified as subtropical and not as a winter gale.
Details on the meteorological factors for the switch will be forthcoming in a future Tropical Cyclone Report.
What this means for the upcoming season is that it counts as the first cyclone of 2023 in the Atlantic basin but will not be named Arlene. Instead, the next tropical depression that forms will be designated Tropical Depression 2 and will get the name Arlene if it strengthens into a tropical storm.
The definition of a subtropical storm requires thunderstorms to focus around the center of the lowest pressure which has warmer temperatures at the core at the mid-levels of the atmosphere.
They differ from tropical storms due to a wider wind field located further from the center compared to pure typical tropical cyclones.
A greater hallmark is that they have no weather fronts linked to their center. Yet this January 18 storm appears to be connected to a strong cold front that moved off the east coast.
The forthcoming post storm analysis report may delve deeper into the reasoning behind the upgrade.