A storm in the north-west Atlantic is forecast to reach hurricane-force winds this week and will not, at any point, be a hurricane.
Subtropical Storm Josephine formed late on Wednesday afternoon several hundred miles south of Cape Cod, Massachusetts, and is forecast to keep intensifying as it moves away from the United States, staying south of Nova Scotia. The account comes from Irene Sans, Bob Henson and Jeff Masters, writing for Yale Climate Connections.
The National Hurricane Center's 11 a.m. AST update had Josephine moving north-east at 12 mph, with maximum sustained winds of 65 mph.
"Note that even if its sustained winds do reach hurricane strength, Josephine would not be designated a hurricane unless its structure were to morph from subtropical to tropical, which is not expected," the authors write.
A subtropical storm has both tropical and non-tropical characteristics, usually drawing its energy from a combination of ocean heat and temperature differences in the atmosphere. Unlike a tropical system, whose strongest winds sit close to the centre, a subtropical storm concentrates its strongest winds farther out. It often has a warm core only in the lower atmosphere, and its thunderstorms are usually displaced well away from the middle.
Josephine is the tenth named system of the 2026 Atlantic hurricane season and its first subtropical storm. The season's tally stands at ten named storms, one hurricane, one major hurricane, and an accumulated cyclone energy index of 19, which is 17 per cent of average for the date.
Four of this year's named storms have reached the United States, two of them billion-dollar storms. On average the country sees three named storms make landfall in a season, two of them hurricanes.
Persistent onshore winds and waves pushed a storm surge of more than two feet to Duck, on North Carolina's Outer Banks, at high tide on Wednesday and Thursday. The resulting flooding was classed as "Minor" but was enough to damage NC-12, the road linking the islands to the mainland, which is now closed with an emergency ferry service to run until repairs are done. The same road was damaged by a nor'easter in September and closed for a week.
Gale warnings run through at least Friday afternoon, especially across coastal New England, with northerly gusts to about 40 mph and seas as high as 14 feet in the waters near Nantucket.
Josephine's career as a named storm will be short. It is forecast to become extratropical, with hurricane-force winds, by late Thursday or early Friday, to pass more than 150 miles south of St John's in Newfoundland and Labrador, and to be absorbed by a larger low-pressure system to the north by Sunday.
Subtropical storms are uncommon but not rare. Subtropical Storm One of 1968 is among the earliest officially documented in the Atlantic, and the basin officially recognises about one a season, though a study in the American Meteorological Society's Journal of Climate identified an average of 4.4 subtropical cyclones a year between 1958 and 2002. Last season's, Karen, lasted two days and formed at 44.5 degrees north, farther north than any other tropical or subtropical cyclone in the Hurricane Center's records.
The distinction being drawn here is not about wind. Josephine may blow at hurricane force and will still not be a hurricane, because the word describes where a storm keeps its thunderstorms.
Measured against the definition, Josephine fails on three counts. Its strongest winds are too far from its centre. Its warm core reaches only the lower atmosphere. Its thunderstorms are displaced well away from the middle. These are all questions of internal arrangement.
A storm cannot, therefore, be promoted by blowing harder. It must be reorganised. To qualify, Josephine would have to move its own weather in towards its own centre, which is not expected of it.
The Department of Unnecessary Research notes that the matter will be settled on Sunday, when a larger low-pressure system absorbs Josephine entirely and it ceases to be any category at all.
The wind reaching Nova Scotia on Friday will be of hurricane strength. It will not be told.