A complex and potent storm system brought rain, freezing rain, sleet and even a tornado threat to the Carolinas on Tuesday, with ice knocking out power to thousands of customers in the foothills and mountains.

The worst of the weather apparently was in the foothills west and northwest of Charlotte, where up to a half-inch of ice accumulated. More than 12,000 power outages were reported shortly after 2 p.m.

Heavy rain that fell in Charlotte caused a few reports of flash flooding. The N.C. Department of Transportation said the ramp from the outer loop of the Brookshire Freeway to southbound Interstate 77 was closed for a while Tuesday morning due to flash flooding.

Temperatures hovered in the mid 30s Tuesday morning as the heaviest rain fell, but as the center of the low pressure system pushed northeast across the Carolinas on Tuesday afternoon, some of the warmer air on the southeast side of the low began filtering into the Charlotte area.

The 2 p.m. temperature in Charlotte was 45 degrees -- about 10 degrees warmer than in Statesville and Hickory. It was even warmer just a short distance to the southeast, with Wadesboro and Camden (S.C.), each about 50 miles away, reporting 55-degree temperatures. It was in the low 70s in the Charleston area.

As of early Tuesday afternoon, more than 1.1 inches of rain had fallen in Charlotte.

Areas in the warm section of the storm system could get severe weather Tuesday afternoon, meteorologists said. A tornado warning was issued Tuesday morning south of Charleston, but no twister was sighted.

The only reported temperature at or below freezing at 2 p.m. was the 32-degree reading in Boone.

The heaviest freezing rain fell along the Blue Ridge and northward into Watauga and Wilkes counties. Duke Energy reported 10,500 customers without power -- with 4,800 of those in Henderson County. McDowell County, served by both Duke Energy and Rutherford Electric, had more than 2,500 customers without power. About 1,100 Duke Energy customers in Polk County were affected.

Caldwell County, served by both Duke Energy and Blue Ridge Electric, had about 1,000 outages. Another 850 outages were reported in Wilkes County.

Ice accumulations of up to 1/2 inch were reported east of Asheville and near Hendersonville.

Reports on social media and weather Internet bulletin boards indicate about 2/10 of an inch of ice accumulated in northern Cleveland County, with between 1/10 and 2/10 of an inch in higher elevations of Rutherford, Burke, McDowell and Caldwell counties.

Boone was hard-hit by both sleet and freezing rain. An icy glaze covered sidewalks and some streets in Watauga County, where there were about 400 power outages reported.

A glaze was reported on power lines and tree limbs in Hickory, Taylorsville and Wilkesboro. And there were reports of slushy streets at daybreak in Hudson, in southern Caldwell County. Heavy sleet fell early Tuesday in Watauga County, leaving roads an icy mess in Boone.

Freezing rain also was reported in the Winston-Salem and Greensboro areas.

Schools were closed in Alleghany, Ashe, Avery and Watauga counties. There were delayed openings for the Alexander, Caldwell, Iredell-Statesville, McDowell and Wilkes county systems, along with Appalachian State University, Caldwell Community College, and Wilkes Community College.