Squall Line Likely to Move through South Carolina Wednesday Night

Apr 28, 2020

Update as of Noon Wednesday:

Mostly sunny skies over the Palmetto State early Wednesday afternoon are not expected to last much longer. Showers and a few thunderstorms could develop over the Upstate as soon as the late afternoon hours. Nearly all high-resolution model simulations continue to forecast a squall line marching across the state tonight into early Thursday morning. The line may not produce a lot of lightning, but heavy rain and strong, gusty winds are likely to accompany this line. Widespread gusts of 35 to 55 mph are possible, with even a few stronger gusts with persistent thunderstorms within the line.

Here are the most likely times of arrival for selected locations across the state:

Wednesday 6 to 11 pm: Upstate, including Greenville and Spartanburg
Wednesday 9 pm to Thursday 3 am: Midlands, including Rock Hill, Columbia, Aiken, and Sumter
Thursday 2 to 6 am: Pee Dee region, including Florence, Conway, Bennettsville
Thursday 2 to 7 am: Lowcountry and Grand Strand, including Charleston, Orangeburg, Hilton Head, Myrtle Beach

Rainfall totals of around one-half inch are forecast in the Lowcountry, with upwards of 2 inches in parts of the Upstate. Conditions are expected to improve on Thursday morning over much of the state, but the rain may not exit the Grand Strand area until early Thursday afternoon.

Original article from Tuesday evening:

It may sound like a broken record for many South Carolinians, but strong thunderstorms are likely to bring the risk of damaging wind gusts again Wednesday evening into Thursday morning. The tornado risk far lower than previous events, but one cannot be ruled out.

The latest storm is forming over central United States as of late Tuesday afternoon. Southerly winds ahead of this storm are expected to become strong through a large portion of the atmosphere, acting to bring back moisture from the Gulf of Mexico. A line of thunderstorms is expected to form ahead of the cold front. Thanks to the strong atmospheric winds, these thunderstorms will have the potential to produce pockets of damaging wind gusts along the line.

The latest high-resolution models are forecasting widespread wind gusts of 35 to 55 mph with this line. As of mid-afternoon Tuesday, the Storm Prediction Center is not outlining a risk for tornadoes across the state. Residents are encouraged to monitor the forecasts for possible changes during the day Wednesday.

Some showers may trail the line of thunderstorms across the state, but most of the rain should move offshore by mid-afternoon on Thursday. A period of quieter and much warmer weather is likely over the upcoming weekend.