Storms have remained mostly at bay today (aside from a few popups in the Walterboro/Summerville corridor) as we put in another hot day with highs topping out at 95° at the airport and 92° at Downtown.
We’ve seen showers and thunderstorms essentially split the area so far today; severe thunderstorms with even a few tornado-warned cells fired up in North Carolina, while a separate round of convection has been ongoing in far southern Georgia into Florida. This has kept the Charleston Metro Area fairly quiet, but I suspect that will be changing fairly soon as a frontal boundary continues its southward trajectory across the state. Radar is doing a good job at picking out an outflow boundary cutting through the Midlands right now, which has caused storms to fire in the Columbia metro area.
This outflow boundary is approaching a few smaller popup storms in Orangeburg and northern Berkeley counties. The atmosphere over Charleston continues to be fairly ripe for thunderstorm development, and short-term models continue to indicate additional shower and thunderstorm coverage developing in the I-95 corridor by 10PM. With the loss of daytime heating, instability has been waning, but there is still more than enough fuel for some loud and rainy thunderstorms in spots tonight.
The front helping to drive all this will stall out across the area tomorrow. With plenty of available moisture and instability, we’ll see several rounds of showers and thunderstorms over the next few days. I’ll have more details in another post later this evening.
Temperatures will once again reach the mid-90s this afternoon across the area (fun fact: yesterday was the first 95° day all year at the airport). Combined with moisture-laden air characterized by dewpoints near 80°, this will once again drive the risk for excessive heat indices upwards of 115° near the coast, where an Excessive Heat Warning is in effect for today. For the inland counties, a Heat Advisory will be in effect with heat indices approaching 110°. Regardless of whether you are in the advisory or warning area today, you’ll want to take precautions against heat illness if you must be outside during the afternoon.
Showers and thunderstorms look to initiate a little later in the day than we saw yesterday, with the best risk of storms coming in the late afternoon and early evening hours. Models suggest a line of thunderstorms could develop and move across the area today. Timing is always a question mark, but I would be on guard for storms starting about 3-4 PM, with the earlier timeframe the further north and west you are. Available energy will be abundant with such strong surface heating and moist dewpoints. Thus, a few storms could be on the strong to severe side with damaging wind gusts, but frequent cloud-to-surface lightning and pockets of heavy rain remain the overwhelming concern from any storms that form this afternoon.
A cold front looks to get close to the area tonight. This will help shut off the oppressive heat of the last few days, but at the cost of another few days of on and off heavy, flooding rainfall. Will have more on the upcoming week later this evening.
We will continue our string of hot days this weekend as we remain under mostly westerly flow at the surface and aloft. A cold front will be closer to the area, though, and this along with some upper-level energy will instigate a few more showers and thunderstorms starting Saturday afternoon. A few of these storms could turn severe with damaging wind gusts the primary concern; locally heavy rain and lightning will also certainly factor in. Shower and thunderstorm chances continue into Sunday, though it won’t rain all day.
Heat and humidity will continue to combine for heat indices around 110° on Saturday and perhaps approaching that number again on Sunday. A heat advisory is in effect for Saturday afternoon as a result; you’ll once again want to take heat safety precautions if you must be outside.
The heat will back off Monday, but at the cost of the resurgent potential for isolated flooding rainfall as deeper moisture and upper-level features become favorable once again for very heavy rainfall.
Friday will be the hottest day of 2021 so far. Temperatures will soar into the upper 90s in the afternoon as deep westerly to northwesterly flow in the troposphere pins the seabreeze to the coast, keeping the cooler marine air at bay for much of the day. On the other hand, this will allow very humid air characterized by dewpoints approaching 80° to pool near the coast. When the seabreeze finally begins its inland trek in the mid-to-late afternoon, the highest heat indices will then be realized as this incredibly moist air moves across the much warmer air found over land. Given this potential, an Excessive Heat Watch is in effect for the Tri-County area. Ridging aloft will put the kibosh on any shower or thunderstorm activity, so don’t count on that to bring any relief, either.
If it’s at all humanly possible, avoid exertion in the heat of the day tomorrow. If you must be outdoors, get shade and hydration on a very regular basis. If you begin to feel ill, move into an air-conditioned area immediately. If you feel faint and your skin is hot to the touch, that’s quite possibly heat stroke — a 911-worthy medical emergency requiring swift treatment.
High heat will continue through Sunday, and heat advisories for heat indices approaching 110° are certainly possible. Please take it easy!
We’ll trade the persistent rain of the last few days for a real taste of summer beginning on Thursday. Temperatures will easily rise into the low 90s in the afternoon under mostly sunny skies as high pressure builds in aloft and at the surface. The humidity will make it feel closer to 105°, which is as hot as the heat index has been all summer. Take appropriate precautions: Plenty of water, plenty of shade, and most importantly, look before you lock. One hot car death is too many.
Today will continue to feature scattered showers and thunderstorms, especially this morning as slow-moving storms develop and move in from the west. Flooding will certainly be a concern wherever thunderstorms set up and rain for long periods. The next high tide will be at 12:07 PM.
It won’t rain all day, however; high-res models have this batch of storms eventually fizzling out by early this afternoon. Another round of storms could fire along the coast this evening, and this may drive additional heavy rain concerns before departing later tonight.
This will be our last day in the 80s until next week; the hottest temperatures of the season will begin Thursday and last into Sunday with highs well into the 90s and heat indices approaching 110°. (More on that later today.)
