A slower frontal progression from the north will allow air temperatures to head back into the mid-to-upper 90s on Sunday, prompting another round of Heat Advisories and juicing up the atmosphere for another round of strong to potentially severe thunderstorms in the afternoon and evening.
With the slower progression of the front, expect another round of hot and humid temperatures for Sunday. Lows bottom out in the upper 70s inland to around 80° at the coast and in downtown Charleston, which has only gone below 80° once in the past week thanks to the heavy rain on Friday. From there, we’ll warm back to the mid-to-upper 90s in the afternoon. Dewpoints in the 70s will once again drive heat indices well into the 100s. Closer to the Highway 17 corridor, heat indices should spike to 109-110° in the immediate wake of the seabreeze. This prompted a Heat Advisory for Berkeley and Charleston counties. While Dorchester will still feel plenty of heat, it won’t rise to the Heat Advisory criteria of 108° for two or more hours.
As we get into the afternoon and convective temperatures are reached, another round of showers and thunderstorms will develop along the seabreeze along with airmass storms further inland. As storms gust out, their outflow boundaries will interact and generate additional thunderstorms. The environment will be conducive to damaging downburst winds, with a wind-driven level 2 out of 5 severe weather risk across much of South Carolina as a result. A few more Severe Thunderstorm Warnings seem probable, so be sure to listen for those warnings and head indoors if storms threaten.
There will also be a risk for heavy rain from these thunderstorms, and with water levels reaching the 7′ coastal flooding threshold in Charleston Harbor between 6-8 PM, any storms downtown could lead to another round of flooding and road closures. Be alert to possible Flash Flood Warnings once again.
The edge comes off the heat a bit as we head into next week, but at the cost of widespread showers and thunderstorms with a decaying front in the area. More typical summertime conditions return by midweek…