As Hurricane Matthew barrels northward in the Atlantic Ocean, some areas on the coasts of Florida, Georgia and the Carolinas are bracing for as much as 10-12 inches of rain, according to the National Weather Service.

But Hall County is unlikely to see anywhere near that amount of precipitation. Vaughn Smith of the National Weather Service said the area is likely to see a maximum of a half inch of rain. The weather service is calling for a 20 percent chance of showers and thunderstorms Friday and mostly sunny weather Saturday in Hall County.

“This will not be a drought-buster for us,” Smith said.

Smith said a frontal boundary from the Mississippi River Valley has helped push Matthew’s projected track mostly offshore, leaving the highest rainfall totals over the ocean and much less inland.

Forecasters have placed all 100 miles of the Georgia coast under a hurricane watch.

The National Hurricane Center said Wednesday that Hurricane Matthew could bring powerful winds and dangerous storm surge to Georgia from the city of St. Marys near the Florida state line to Savannah.

Forecasts show Matthew will likely pass offshore Saturday, but close enough to land to cause potentially serious damage.

The hurricane center says tropical storm winds of 39 mph or greater could reach coastal Georgia today, while hurricane-force winds of 74 mph or greater could arrive late Friday. Several feet of storm surge are possible, especially if peak storm conditions occur during high tide.

Early in the day Wednesday, Chatham and Glynn counties called for a voluntary evacuation of about 47,000 residents. The city of Tybee Island issued a mandatory evaluation order that began at 3 p.m.

The Georgia coast hasn’t seen such a hurricane evacuation since a near-miss with Hurricane Floyd in 1999. No storm has made direct landfall along the state’s coastline since Hurricane David in 1979, and the last time Georgia saw a direct hit from a Category 3 or greater storm was in 1898. Category 3 hurricanes have winds in excess of 110 mph.

Public school classes in the Savannah area were canceled for Wednesday through Friday, and Gov. Nathan Deal has declared a state of emergency for 30 southeast Georgia counties and ordered state emergency management officials to work closely with local agencies.

Georgia Power said it “is monitoring the changing weather around the clock, mobilizing crews and preparing to respond to any service interruptions, which may occur.”

Meanwhile, wind gusts up to 30 mph Thursday night and 25 mph during the day Friday might be the closest Hall County comes to experiencing the storm’s effects.

The Red Cross is also preparing for the storm and is seeking blood donations to help with possible fallout from Matthew.

“We encourage eligible donors to please give blood or platelets before the storm arrives to help ensure we have a readily available blood supply for patients in need,” the agency said in a news release Wednesday. “All eligible donors in parts of the country unaffected by Hurricane Matthew are also urged to schedule an appointment.”