Trough

A mid-latitude trough drawing Ophelia like a magnet northeast is expected to lift today and stop influencing the storm.

Pressure ridge

A strong high-pressure ridge is expected to replace the trough, acting like a wall and forcing Ophelia to turn back toward the coast late today or early Sunday.

Ridge strength

Everything depends on how strong that ridge is. If it’s strong enough, it could push Ophelia south of the state. If it’s weak, Ophelia could go north of the state’s coast. If it’s in between, S.C. could be in for trouble.

Winds

Upper-level winds that could keep Ophelia from strengthening are expected to move away, allowing it to strengthen to a 90-mph storm by landfall.

Computer models

One of the major computer models used to forecast hurricanes’ paths shows Ophelia slipping past the ridge and going north, away from land.