Subtropical Storm Andrea (2007)

Subtropical Storm Andrea

Subtropical storm (SSHWS/NWS)
Andrea shortly before being classified as a subtropical storm on May 8
Formed	May 9, 2007
Dissipated	May 11, 2007
Highest winds	1-minute sustained: 60 mph (95 km/h)
Lowest pressure	1001 mbar (hPa); 29.56 inHg
Fatalities	6 indirect
Damage	Unknown
Areas affected	Virginia, Southeastern U.S., Bahamas
Part of the 2007 Atlantic hurricane season

Subtropical Storm Andrea was the first named storm and the first subtropical cyclone of the 2007 Atlantic hurricane season. It developed out of a non-tropical low on May 9 about 150 miles (240 km) northeast of Daytona Beach, Florida, three weeks before the official start of the season. After encountering dry air and strong vertical wind shear, Andrea weakened to a subtropical depression on May 10 while remaining nearly stationary, and the National Hurricane Center discontinued advisories early on May 11. Andrea was the first pre-season storm to develop since Tropical Storm Ana in April 2003. Additionally, the storm was the first Atlantic named storm in May since Tropical Storm Arlene in 1981.

The storm produced rough surf along the coastline from Florida to North Carolina, causing beach erosion and some damage. In some areas, the waves eroded up to 20 feet (6 m) of beach, leaving 70 homes in danger of collapse. Offshore North Carolina, high waves of 34 feet (10 m) and tropical-storm-force winds damaged three boats; their combined nine passengers were rescued by the Coast Guard, although all nine sustained injuries. Light rainfall was also reported in some coastal locations. Damage was minimal, but six people drowned as a result of the storm.

In early May, an upper-level trough dropped southward through the western Atlantic Ocean, forcing a back-door cold front—a cold front that moves southwestward ahead of a building surface ridge to its north or northeast—southward. For several days, forecast models had anticipated for the trough to evolve into a closed low pressure area, and on May 6, a frontal low with a large and well-defined circulation developed about 90 miles (140 km) east of Cape Hatteras. The low maintained scattered convection around its circulation center, and in conjunction with the strong high pressure to its north, a very tight pressure gradient produced gale-force winds near the coastline. The extratropical storm tracked southeastward and later turned to the southwest while steadily deepening; on May 7, it attained hurricane-force winds. With a lack of tropical moisture, its corresponding convection was minimal and scattered.