A battle of the seasons is anticipated over the next couple of days as a powerful cold front approaches the Southeastern United States delivering a wet Christmas Eve followed by a frigid arctic air mass Christmas Day.
On Wednesday a deepening low pressure system near the Great Lakes was continuing to track eastward while dragging a cold air mass southward and pulling a long and powerful cold front which stretches down to the Gulf Coast.
Ahead of the cold front southerly winds will deliver above average temperatures to much of the Southeast United States including South Carolina for Christmas Eve. Temperatures are forecast to rise into the upper 60s. Coastal regions from Charleston and southward could even climb into the lower 70s by the afternoon. Cooler conditions are anticipated in the Upstate with highs in the mid to upper 50s.
Overnight Wednesday and through Christmas Eve the strong cold front will approach South Carolina from the west. Ahead of the cold front showers and a few thunderstorms will move through the Upstate and western parts of the Midlands beginning Thursday morning and into the early afternoon. Heavy rainfall could trigger localized flash flooding especially around the Appalachians. The severe threat will likely be minimal for western locations, however the line of thunderstorms is expected to gradually strengthen as it moves eastward towards the coast late Thursday afternoon. Fierce winds a few hundred feet above the ground will create an environment of strong wind shear ahead of the approaching cold front. This will help to fuel thunderstorm activity through the afternoon with some storms capable of producing strong, potentially damaging wind gusts, and even a few isolated tornadoes for parts of the eastern Midlands, Pee Dee, and the Lowcountry.
The Storm Prediction Center Wednesday issued an Enhanced Risk (risk level 3 out of 5) for extreme southeastern portions of Pee Dee for the chance of strong to severe thunderstorms Thursday ahead of the powerful cold front. A Slight Risk (risk level 2 out of 5) is in place for the remainder of Pee Dee and northern parts of the Lowcountry including the city of Charleston.
Showers and thunderstorms are anticipated to move offshore late Thursday evening with the cold front quickly passing overhead overnight. Upon the passage of the cold front temperatures will rapidly drop overnight Christmas Eve and into Christmas Day. Some remnant precipitation behind the passage of the front could translate to a wintry mix or even snow. However, this will likely only occur in higher elevations in the Upstate.
Once the cold front moves through the region, the jet stream following behind the front will dive southward, encompassing most of the Southeast for Christmas Day. Morning low temperatures are expected to sink into the 20s across the Upstate and Midlands with 30s towards the coast. Afternoon temperatures will remain frigid for Christmas Day with highs ranging from the upper 30s in the west to the lower 40s along the coast. Even colder temperatures will move in overnight Christmas Day and into Saturday with most areas state-wide falling into the 20s. Wind chill values could lower into the teens.
Mostly clear skies will dominate the Palmetto State for the weekend with temperatures gradually warming as the arctic air from the jet stream shifts eastward into the Atlantic.