A Winter Storm Watch has been issued for the Upstate and portions of the Midlands and Pee Dee ahead of a storm that will sweep through the Mid-Atlantic this weekend. Periods of heavy snow, freezing rain, and wintry mix are all expected from the system which should arrive Saturday night and linger through late Sunday.
On Thursday afternoon, observations indicated that an deepening area of low pressure off the Pacific Northwest coast. The vigorous Alberta Clipper, so named for its origin in the Canadian Rockies, will push into the Northern Plains early Friday. It is at that point that the system will be accelerated to the Southern Plains and Lower Mississippi Valley by an amplified jet stream. The strengthening low pressure will likely be guided through the Southeast on Saturday, before lifting through the Mid-Atlantic into the Northeast on Sunday and Monday.
The leading edge of this powerful winter storm could push into South Carolina as early as Saturday night. Both American and European weather models are in consensus, as of writing , that a wide swath of freezing rain and sleet will drape across the northern Midlands and Upstate as a shallow layer of warmer air moves in at around 5,000-feet. For areas close to the western North Carolina border, precipitation is likely to fall in the form of sleet, freezing rain, and some continued snow by the afternoon as warmer air aloft wins out over colder temperatures.
In addition, freezing rain is most likely in and near Columbia Sunday morning, with widespread snow and possibly some sleet likely along and north of I-85. In these areas, road conditions are expected to quickly deteriorate, and travelling will become dangerous.
Temperatures over the southern Midlands and the Low Country are expected to remain warm enough overnight Saturday into Sunday that the predominant form of precipitation will be rain. In these areas, locally heavy rainfall rates could lead to flooding in poorly drained and low lying areas.
Precipitation should gradually exit the Palmetto State by Sunday evening, however moisture wrapping around the backside of the exiting low pressure could provide continued snow showers in the higher elevations of Oconee, Pickens, and Greenville Counties into early Monday.
Specific timing and totals for snow, sleet, and freezing rain will be fine-tuned over the next 24- to 36-hours as the event gets closer to unfolding. Regardless of specific amounts of wintry precipitation, a wide range of impacts are likely to be felt across much of the state.