Subtropical Storm Josephine developed off the East Coast of the U.S. on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Subtropical Storm Josephine was located at latitude 37.4°N and longitude 69.5°W which put the center about 265 miles (425 km) south of Nantucket, Massachusetts.  Josephine was moving toward the north at 6 m.p.h. (10 km/h).  The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h).  The minimum surface pressure was 990 mb.

The U.S. National Hurricane Center designated a low pressure system off the East Coast of the U.S. as Subtropical Storm Josephine on Wednesday afternoon.

Subtropical Storm Josephine made a transition from an extratropical cyclone to a subtropical cyclone on Wednesday.  The warm front and cold front that had been attached to the low pressure system dissipated.  Even though the fronts had dissipated, the distribution of thunderstorms in Subtropical Storm Josephine was asymmetrical.  Thunderstorms were occurring in bands in the northern and western parts of Josephine’s circulation.  Bands in the eastern and southern parts of Josephine consisted primarily of showers and lower clouds.

The distribution of wind speeds in Subtropical Storm Josephine was also asymmetrical.  Winds to tropical storm force extended out 415 miles (665 km) in the northern half of Josephine’s circulation.  Winds to tropical storm force extended out 150 miles (240 km) in the southern half of Subtropical Storm Josephine.

Subtropical Storm Josephine will move through an environment favorable for the intensification of a subtropical storm during the next 24 hours.  Josephine will move over water where the Sea Surface Temperatures are near 24°C.  It will move under the southeastern part of an upper level trough that will be over the Great Lakes.  The upper level trough will produce southwesterly winds that will blow toward the top of Josephine’s circulation.  Those winds will cause strong vertical wind shear.  However, the upper level winds may also contribute to upper level divergence.  Subtropical Storm Josephine could intensify on Thursday because of the upper level divergence.

The upper level trough over the Great Lakes will steer Subtropical Storm Josephine toward the northeast during the next 24 hours.  On its anticipated track, Subtropical Storm Josephine will pass south of Nova Scotia on Thursday.