Damaging winds, isolated tornadoes, and heavy rain are likely across portions of the Palmetto State beginning Sunday evening, lasting into Monday morning. Locations at greatest risk for the destructive storms are the Lowcountry, PeeDee and Grand Strand regions.
A warm front is expected to lift north through the southern half of South Carolina overnight, followed by a strong storm system and cold front approaching from the west on Monday. The warm front will separate a cool, stable air mass to the north from an increasingly warm and humid one farther south. Both of these boundaries will be the focusing mechanism for numerous clusters of thunderstorms over the nearly 18-hour period.
Forecast models suggest strong winds blowing in opposite directions with height are likely to create an environment favorable for rotating storms through the period, especially late Sunday night and early Monday morning. Conditions are also conducive for damaging wind gusts up to 70 mph and hail up to the size of nickels.
In a coordination call with our team at South Carolina Public Radio Sunday afternoon, Meteorologist Ray Hawthorne compared last Monday's event to this one, stating tonight's was more "messy and complicated." He posted a Twitter thread earlier in the day to explain why.
1/n - Will focus on #SouthCarolina first: strong warm front is over southern Georgia at midday. It's easy to pick out as the colors transition from purple to light orange quickly. Along and south of the boundary is where the air is warm, humid, and unstable. #scwx pic.twitter.com/YNL7l6r9dQ
— Ray Hawthorne (@ray_hawthorne) April 19, 2020
The most unstable air is likely to reside near and southeast of the I-20 corridor from Augusta, GA to Columbia and Florence, SC. The Storm Prediction Center has issued an Enhanced Risk (Risk level 3 out of 5) for the Lowcountry, Pee Dee, and eastern parts of the Midlands. The risk is “slight” (level 2 out of 5) for central and western sections of the Midlands, along with the far eastern counties in the Upstate.
This showers and thunderstorms will likely push offshore by midday Monday, as the cold front swings through. High pressure will begin to build from the northwest Tuesday, keeping skies clear and rain-free through at least midweek. The next storm system that could produce rain or thunder is on target to arrive Thursday.