during the first week of september, a cold front moved off the east coast of the united states and stalled over the atlantic ocean. by september 8, a weak frontal wave began developing along the cold front. late on september 9, convection increased over the broad low pressure area, and the overall system intensified beneath an upper-level low. subsequently, the system abandoned its frontal features as its appearance became more circular. with persistent but limited convection near and to the west of the center, the national hurricane center (nhc) estimated the system developed into a subtropical depression late on september 10 about 375 mi (604 km) west-southwest of bermuda; it was considered subtropical because the upper-circulation was believed to have been cold-core. operationally, advisories on the system were not initiated until 21 hours later.