We'll be in an active weather setup through the end of this week. This afternoon, parts of the Upstate are under a Severe Thunderstorm Watch until 4:00 p.m. Severe storms have already erupted over the Upstate.
This map shows the area covered by a Severe Thunderstorm Watch until 4:00 p.m., including Greenville, Spartanburg, Cherokee and York Counties.
We may see more severe thunderstorm watches issued this afternoon. Conditions are favorable for storms to become severe in the summery air mass present over the state today. It's very unstable over the northern half of the state, and the setup is quite favorable for damaging wind and hail. We could see higher-end damaging wind and hail (local 70+ mph wind gusts and larger-than-golf ball hail). The tornado risk is very low, despite the potential for supercell storms to form, because the wind shear that causes them to form will only exist well above the surface, and cloud bases will be relatively high.
SPC's Severe Weather Outlook graphic for today and tonight with South Carolina highlighted shows a severe storm risk for most of the state, highest over the
Upstate and vicinity, which is covered with a level 3 of 5 severe storm risk.
The storms will march southeast through this evening and should reach the I-20 Corridor toward nightfall. After it gets dark, the storms should become less intense, but locally damaging wind and hail will remain a threat with the storms as they cross the Pee Dee and Midlands tonight while they wane.
While our storms romp over the northern part of the state through this evening, we will watch a major outbreak of severe thunderstorms and tornadoes take shape over the lower Mississippi Valley. These thunderstorms will plow east across the zone between the Tennessee and Ohio valleys tonight. The unseasonably sultry air over our region will ensure those thunderstorms survive through the night and reach us. Only the timing is in question. Some of our computer guidance brings the storms to the Upstate by midnight, while others hold them off until 3-4 a.m. Faster is usually better for intense thunderstorm outbreaks, so if the exact timing matters to you, be ready for the storms to start rumbling through the Upstate during the midnight to 2 a.m. time frame.
By the time the storms get to South Carolina, they likely will be consolidated into a squall line. This setup is favorable for damaging wind and hail and less favorable for tornadoes, though the tornado risk will be non-zero with this round of storms.
This line of storms will push southeastward through the northern half of the state and should arrive in the I-77 and I-20 Corridors before daybreak. The intensity should lessen, but these storms can still produce locally damaging winds even into early Thursday.
SPC's Severe Weather Outlook graphic for Thursday has the entire state in a level 2 of 5 risk area for severe thunderstorms. However, there is a good chance the severe storms mostly occur before this outlook period begins at 8 a.m. along and north of I-20.
What happens next is uncertain, but it is likely that the storms reload over the Coastal Plain starting around midday Thursday, especially over the Lowcountry, where SPC indicates the highest severe storm risk. So, this area will be the one to watch for locally damaging wind and hail. Once again, higher-end wind and hail will be possible, and the tornado risk will not be zero close to the Savannah River. These storms should diminish or move offshore by evening. We'll have to watch out for more storms popping over the Upstate again in the afternoon, but the earlier rounds of thunderstorms should limit the risk in that area.
We'll have a quiet spell Thursday night before another disturbance rolls through on Friday and triggers more thunderstorms, some severe. While most of the state will be at risk, the Lowcountry and Grand Strand appear to have the highest risk for severe storms. Once again, damaging wind and hail should be the primary risk, with a low but non-zero tornado risk.
SPC's Severe Weather Outlook graphic for Friday and Friday night, showing a level 1 of 5 risk for storms over most of South Carolina.
It still looks like we'll get a nice break in the action for the upcoming weekend as it turns cooler and less humid for a few days behind a cold front that will cross the state in the wake of Friday's storms. Moisture and stormy weather will likely return by Tuesday.
Have your severe storm prep "A-game" ready for the storms headed your way. Have at least two ways to receive warnings, especially tonight as storms hit while most of us are trying to get to sleep. This will be a night to try to get to bed early because some "bumps in the night" are likely. As always, tornado and severe storm prep information is available from SCEMD and Ready.gov.
