The latest batch in the seemingly endless waves of heavy rainfall that have moved across the state this winter is on track to move through Tuesday afternoon into Tuesday night.
A stationary front extends east to west from near Georgetown to about Aiken at midday Tuesday. Scattered showers are occurring near the front, along with a few thunderstorms from the Columbia metro area westward to the Greenwood and Anderson areas. More concentrated thunderstorms in the Atlanta metro area through the mountains of North Georgia and Alabama are expected to move into the Upstate and Midlands during the early and mid afternoon hours before departing around dusk. Localized flash flooding is the primary concern with any persistent thunderstorms; however, residents of the Midlands and even the Pee Dee should be aware that strong wind gusts are not out of the question. It’s unlikely, but a tornado or two is possible, as well.
A disturbance high in the atmosphere over the Southern Plains is expected to move along the front toward South Carolina late tonight into Wednesday morning. This means another round of rain is likely to spread into the Upstate around or a bit before midnight, spreading through the Midlands during the wee-hours of Wednesday morning before moving offshore of the Grand Strand and Lowcountry shortly after dawn Wednesday.
NOAA’s Weather Prediction Center says a widespread 1.5 to 3 inches of rainfall is likely over the Upstate and parts of the Northern Midlands, including the Greenville, Spartanburg, and Rock Hill areas. Some reliable forecast models indicate the potential of amounts reaching 3 to 5 inches, but this would likely be confined to where a few of the strongest, most persistent thunderstorms move over the same location. Lesser amounts of one-half inch or less are forecast in the Lowcountry, but any thunderstorm could easily dump 1 to 2 inches of rain in a few neighborhoods.
The storms tonight may also produce isolated reports of strong wind gusts or tornadoes. At this time, the air is not expected to be strongly unstable, so widespread damaging thunderstorms are unlikely. Despite the low overall threat, residents should still have multiple ways to receive weather warnings as a precautionary measure, including NOAA Weather Radio and Wireless Emergency Alerts (WEA) available on nearly all modern mobile devices.
The most widespread rain and storms are forecast to move offshore by mid-morning Wednesday. A few lingering scattered showers and storms are possible primarily over the Pee Dee and Lowcountry into Wednesday afternoon along an approaching cold front. The afternoon activity is not expected to be hazardous at this time.