MIAMI -- A tropical storm warning was issued Friday for parts of North and South Carolina as Ana approached the U.S. coast, kicking up rough surf and rip currents ahead of what was forecast to be a rainy weekend.
The storm formed nearly a month before the Atlantic Hurricane season officially kicks off June 1. The U.S. National Hurricane Center in Miami said Friday that Ana's maximum sustained winds are near 45 mph with slight strengthening forecast during the next day or so.
The storm is centered about 170 miles south-southeast of Myrtle Beach, South Carolina. The Hurricane Center says it's been nearly stationary over the last few hours but is expected to move north-northwest later in the day.
The tropical storm warning is in effect from the south Santee River in South Carolina to Surf City, North Carolina.
Rain is a concern because the system is moving so slow and won't clear out quickly. Ana is expected to deliver 2 to 4 inches of rain over the weekend, with some areas getting up to 6 inches.
Ana is currently a subtropical system, meaning it has characteristics of both a tropical storm, which gets its energy from warm ocean waters, and a traditional storm system driven by temperature changes.
"There's that just little prefix 'sub' before the storm that has meaning for meteorologists, but to the public it doesn't really matter," said James Franklin, chief of the Hurricane Center's Hurricane Specialist Unit.
Forecasters are also warning people to avoid dangerous surf and rip currents being kicked up by the storm. Some isolated flooding is also expected in some areas along the coast.
"We've lost a lot of lives in rip currents, let's try not to do that this weekend," said Hurricane Center director Rick Knabb.
May storms aren't unusual, with one forming every few years or so, Knabb said. But Ana marks the earliest subtropical or tropical storm to form in the Atlantic since 2003, the Hurricane Center said in a tweet. That storm's name? Ana.