Josephine stays offshore as coastal hazards persist
· BehindLines newsroom
Josephine was moving away from the United States on Thursday, October 22, after changing category while coastal hazards continued. In its final public advisory, issued at 21:00 UTC, the US National Hurricane Center, or NHC, classified it as a post-tropical, extratropical cyclone. Its centre was about 380 kilometres east-southeast of Nantucket, Massachusetts. Maximum sustained winds were 100 km/h.
The sea carries effects beyond the centre
The NHC reported minor coastal flooding, locally moderate, already affecting parts of the US Mid-Atlantic coast. It expected flooding to continue around high tides for the rest of the week. Large swells were also affecting much of the US Atlantic seaboard and parts of Atlantic Canada, with dangerous surf and rip currents possible.
Associated Press also describes coastal effects, drawing on US weather services.
The system's earlier hybrid stage
NASA says Josephine received its name on October 21. Its notice published on October 22 accompanies an image acquired the previous day by the Terra satellite. The explanation describes a subtropical system drawing energy both from warm ocean water and from temperature differences between air masses.
That combination helps explain why the storm's name and its effects cannot be understood simply by measuring how far its centre lies from the shore.
The transition has occurred; strengthening is still forecast
The NHC's 21:00 UTC discussion identifies a developing frontal structure and an elongated centre: the transition to an extratropical system has now occurred. It still forecasts strengthening during the night of October 22–23, with hurricane-force winds, followed by weakening. That wind strength remains a forecast; it does not mean Josephine has been classified as a hurricane.
The NHC is ending its advisory series for this system and directing further monitoring to marine forecasts and local weather services. The end of that series therefore does not announce an end to coastal hazards.
In its marine forecasts on the evening of October 22, the OPC still forecasts that strengthening offshore. Boston’s weather office keeps gale warnings for some coastal waters through Friday, October 23.