Subtropical Storm Ana
Subtropical Storm Ana is seen in a view from the NOAA Suomi National Polar-obiting Partnership day/night band satellite captured around 02:51 am EDT (06:51 GMT) May 8, 2015. REUTERS/NOAA/NASA/Handout

A subtropical storm formed off the south east coast of the US on 7 May, becoming the first named storm of the 2015 hurricane season in the Atlantic.

According to the National Hurricane Center, Subtropical Storm Ana is "on the verge of becoming a tropical storm". The subtropical storm is located at 165 miles south-southeast of Myrtle Beach, South Carolina and is stationary, the latest advisory from the NHC stated.

A tropical storm warning is in effect from South Santee River, South Carolina to Cape Lookout, North Carolina, the advisory stated. Meanwhile, a tropical storm watch is in effect from Edisto Beach, South Carolina to south of South Santee River.

The NHC stated it expects Subtropical Storm Ana to "begin a north-nothwestward motion overnight". It added that the storm is expected to move north west with a slight increase in forward speed on Saturday 9 May. The centre of Storm Ana will be close to the coast of both South and North Carolina on Sunday, the agency noted.

Subtropical Storm Ana has maximum sustained winds of around 45 mph and higher gusts. The Weather Channel reported that winds gusted over 30 mph on Thursday 7 May in Wilmington, North Carolina.

The storm is expected to continue its transition into a tropical storm by early Saturday. However, the NHC noted, "Little change in strength is expected while the storm approaches the coastline over the next couple of days."

The NHC reported that Subtropical Storm Ana could cause water to rise 1ft to 2ft above ground at high tide in coastal areas from Cape Hatteras, North Carolina south through South Carolina. The storm is also expected to produce between 2in to 4in of rain fall over eastern parts of North and South Carolina.

Subtropical Storm Ana will reach landfall on Sunday, according to the Weather Channel. It noted: "While slowly weakening after landfall later Sunday into Monday, onshore gusty winds will continue along the southern coast of North Carolina, spreading northward into the Outer Banks and Virginia Tidewater Monday."