The season's first winter storm is poised to move into portions of upstate South Carolina Sunday, where several inches of snow and sleet are expected.
A Winter Storm Warning is in effect through midday Monday for areas along and west of the I-85 corridor from Anderson to Spartanburg. The warning extends east to include Laurens, Union, Chester, York and Lancaster counties of north-central South Carolina.
A Winter Weather Advisory is also in effect for Abbeville, Greenwood, Newberry, Fairfield, Kershaw and Chesterfield counties through Monday evening.
Rain began overspreading much of the state Saturday, when temperatures were safely above freezing. As the storm system strengthens and moves toward the coast, increasing northerly winds will send colder air into the piedmont and upstate regions where a transition into freezing rain, sleet or snow will occur.
The timing of the changeover to frozen precipitation will largely depend on elevation. Subfreezing temperatures are expected first in the Blue Ridge Mountains by sundown Saturday evening. Snow will be the primary precipitation type in these loations for the duration of the event where 4 to 8 inches of accumulation are possible.
Further east, along the I-85 corridor from Greenville to Spartanburg, the rain will change over to freezing rain and sleet during the overnight hours early Sunday. Sleet will become the primary form of precipitation in these areas through Sunday afternoon, before briefly changing to snow as it ends. One to two inches of sleet and snow are expected in these areas from the storm.
For locations under a Winter Weather Advisory, just north and west of Columbia, a dusting to one inch of sleet or snow is expected at this time. However, uncertainty in the track and strength of the storm have yielded lower confidence in frozen precipitation reaching these areas at the present time.
The winter storm will slowly exit Monday, but then be followed by another weaker disturbance crossing the mountains Monday night. This could produce lighter rain or snow showers again Monday afternoon and evening, but yielding little or no additional accumulation.