One (2009)

A low pressure area formed along a decaying frontal boundary off the southeastern U.S. coast in late May. The system developed organized thunderstorms and became Tropical Depression One at 0600 UTC on 28 May 2009 while about 150 nautical miles east-northeast of Cape Hatteras, North Carolina. It moved northeastward then east-northeastward over the Gulf Stream, maintaining intermittent convection through 29 May. Cooler waters and increasing wind shear ended the convection, and the depression degenerated into a remnant low around 0000 UTC on 30 May about 300 nautical miles south-southeast of Halifax, Nova Scotia; the remnant low merged with a frontal system later that day.

The system did not make any landfalls as a tropical cyclone. Its center remained over offshore waters from formation until it lost tropical characteristics and merged with a front while well south of Nova Scotia.

Maximum sustained winds reached 30 knots (35 mph) and the minimum central pressure was 1006 millibars, corresponding to a weak tropical depression at its peak. The official best track lists 30 kt/1006 mb as the depression’s maximum recorded intensity on 28–29 May.

Storm surge and rainfall impacts were minimal to none from this system because it remained offshore and weakened quickly. The report did not list specific surge measurements or notable rainfall totals in coastal cities or counties.

There were no reported deaths or significant damage associated with Tropical Depression One. The system was notable for forming farther north in May than almost all historical May cyclones, having the northernmost genesis point among the 28 known May tropical or subtropical cyclones; its development was not widely expected until about 18 hours before designation.