MIAMI (Reuters) - Meteorologists said a storm moving slowly toward the Carolinas, which is forecast to bring rain, high wind and flooding, had transitioned into a tropical storm early on Saturday, according to the US National Hurricane Center.
Tropical storm Ana, the first named storm of the 2015 Atlantic hurricane season, was lurking some 170 km southeast of Cape Fear, North Carolina around 5 a.m. local time, the Miami-based weather agency announced.
A warning is now in effect for areas along a 443 km swath from South Santee River, South Carolina to Cape Lookout, North Carolina, at the southern end of the Outer Banks, it said.
Forecasts show the system making landfall on Sunday near the border between North and South Carolina. As it swirled on Saturday morning, it packed maximum sustained winds of 95 km/h winds.
Ana stalled on Friday about 265 km south-southeast of Myrtle Beach, a South Carolina beach and golfing resort, before strengthening into Saturday. It is predicted to begin gradually weakening by Sunday morning.
The Hurricane Center said the storm would bring anywhere from 2.5-12.7cm of rain and the storm surge could bring flooding up to 61 cm in coastal areas.
Ana's formation is the earliest appearance of a named storm in the Atlantic since a previous incarnation of Subtropical Storm Ana on April 20, 2003, said Jeff Masters, chief meteorologist for Weather Underground, a commercial weather service.
The Atlantic hurricane season typically runs from June 1 through Nov. 30.
Subtropical and tropical storms do not generate very different wind strengths, but tropical storms cause more rain and have the potential to rapidly intensify into hurricanes, said Masters.
Forecasters with Colorado State University predicted in April that the Atlantic Ocean will see a "well below average" number of hurricanes this season due to cooler Caribbean waters and the El Niño effect.
El Niño, a warming of sea-surface temperatures in the Pacific, increases the odds of a quiet Atlantic hurricane season. El Niño typically brings high wind shear to the tropical Atlantic, disrupting hurricanes as they try to form.