Charleston Weather Blog

Forecast explanations, atmospheric science, and other cool weather-related stuff for Charleston, SC

Friday & the weekend: Stormy end to the work week, but a humidity reprieve awaits

/ August 11, 2022 at 10:31 PM

A cold front will push southward across the area on Friday, likely bringing with it showers and storms especially in the afternoon and evening hours. The convection-allowing models generally agree on some sort of linear storm organization pushing southward into the area tomorrow evening; the greater question is whether storms will fire ahead of it as well. I’d be prepared for periods of unsettled weather throughout the day, and be ready for another commute impacted by showers and thunderstorms. A severe storm or two can’t be totally ruled out, but the main concern will be heavy rainfall and frequent lightning. Cloud cover and rain showers should help keep highs suppressed to the mid-and-upper 80s.

The front will move south of the area and stall out on Saturday, switching winds around to the northeast and beginning to usher in some cooler and drier air the likes of which we haven’t seen since late June. Dewpoints will fall into the mid-60s and cloud cover will scour out somewhat. However, there’s still a slight chance for showers and thunderstorms in the afternoon hours as a wave of low pressure develops along the front. If that wave develops nearby (as tonight’s NAM 3km suggests), it could spread some moisture ashore. That aside, Saturday should actually feel really terrific, especially further inland. Same for Sunday, where partly cloudy skies and mid-60s dewpoints will persist, making for another comfortably warm day across the Lowcountry.

Onshore winds and the recent full moon at perigee could contribute to water levels approaching minor flood stage with the Saturday evening high tide. So far, I’m not expecting any major tidal flooding issues, but it always bears watching with northeasterly wind directions near a full moon.

Rest of the work week: Turning unsettled as a front stalls out

/ August 9, 2022 at 10:17 PM

After a relatively quiet Tuesday, we’ll start to see rain chances trend back up starting Wednesday as a trough develops aloft and a cold front presses southward, which will eventually stall out somewhere in the area over the weekend. We still stay quite warm Wednesday into Thursday as highs top out in the low 90s and heat indices top out in the low 100s. Isolated to scattered showers and storms should develop along the seabreeze in the early afternoon and move inland as the day progresses. Same deal for Thursday, though we could see some additional coverage sprout up as the trough digs in a bit more down the East Coast and the front starts to drive southward a little more. By Friday, the front will be getting closer, and this will instigate greater shower and storm coverage as a result. Temperatures will also run a little cooler — by cooler, I mean upper 80s instead of low 90s — thanks to the more widespread cloud cover and rain coverage.

Heading into the weekend, we look to stay unsettled for at least part of Saturday, but drier air will be punching into the area. We should see a taste of mid-60s dewpoints starting Saturday afternoon, leading into what should be a rather gorgeous (by mid-August standards) Sunday. Fingers crossed these trends in the models continue — typically, it is still tough to get fronts this far south at this point in August, but then again, July’s deluge courtesy of southward-pushing fronts showed us that this hasn’t been a very typical summer. Stay tuned.

The week ahead: On and off showers and storms turn more numerous later this week

/ August 7, 2022 at 9:00 PM

Standard warm & muggy August weather will continue this week with an uptick in shower and thunderstorm coverage coming thanks to a stalling cold front.

Monday looks to remain somewhat on the unsettled side as a mid-level feature known as a TUTT (tropical upper-tropospheric trough — say that five times fast!) continues to whirl into the area. This should help kick off some isolated to scattered showers and storms to start the day near the coast. Eventually, we should see the seabreeze begin to push inland, and along with it, more isolated to scattered showers and storms, with rain chances moving westward with time. Temperatures will generally top out in the upper 80s to around 90° in the afternoon; heat indices will approach 100°.

Expect additional seabreeze-driven showers and storms Tuesday and Wednesday, with highs topping out in the low 90s each afternoon. Storm coverage ratchets up a little beginning Thursday afternoon as a front approaches the area; scattered to numerous storms are possible Friday with the aforementioned cold front approaching the area. We’ll stay unsettled into the weekend, with high temperatures trending down a little further into the 80s in the afternoons thanks to onshore flow and scattered storms.

The severe weather risk this week is low, but an isolated strong or severe storm can never be totally ruled out at this point in the year. Heavy rain and lightning will be the main concerns from thunderstorms, and slow storm motions at times may produce areas of isolated flooding. All in all, nothing terribly out of the ordinary for early-to-mid-August — just make sure the rain gear is close and that your outdoor activities have indoor backup plans.

Friday & the weekend: Standard August fare

/ August 4, 2022 at 6:20 PM

Atlantic high pressure keeps us appropriately warm and muggy by early August standards for tomorrow into the weekend. Onshore flow will help air temperatures run in the upper 80s to low 90s each afternoon, while humidity will make it feel closer to the upper 90s and low 100s.

The aforementioned onshore flow keeps a chance of showers in the forecast Friday morning closer to the coast. Rain chances will migrate inland with time, with a few thunderstorms possible as the seabreeze pushes inland across the area during the afternoon and early evening hours. Saturday’s setup looks similar, too, though the NAM nest is a little less excited about morning showers. Sunday could be a little more active as what looks like a weak TUTT (tropical upper-tropospheric trough) whirls into the area from the east, helping to enhance shower and storm coverage across the area. Overall, the risk for severe weather remains low, but as always, lightning makes every thunderstorm dangerous. When thunder roars, go indoors!

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Tuesday: Another hot early-August day

/ August 1, 2022 at 9:41 PM

More warm and humid weather is on tap for Tuesday as air temperatures once again peak in the mid-90s after starting out in the mid-70s away from the warmer coastline. Mix in humidity and it’ll feel closer to the low 100s, especially as the seabreeze passes by in the afternoon. Rain-wise, it looks to be a fairly typical summer day. We could contend with a few showers in the morning near the coast, with primarily seabreeze-driven isolated shower and storm coverage in the afternoon. Storms will be able to produce some heavy rain and maybe a few strong wind gusts, but severe weather isn’t anticipated.

We could see a little better storm coverage on Wednesday before high pressure rebuilds later in the week. Temperatures will be trending down toward around normal for this point in the year as well, with highs around 90° each day from Thursday into next week.

The week ahead: A hot and humid start to August

/ July 31, 2022 at 10:00 PM

We say goodbye to July and hello to August with appropriately hot and humid conditions for this point in the summer, though we’ll see air temperatures fall a bit as the week progresses, which will have a little downward pressure on heat indices primarily as we get into the weekend. We have some rain chances in there as well, particularly mid-week.

Monday will be the hottest day air temperature-wise as highs look to peak in the mid-90s, though some drier air aloft will mix down and bring dewpoints to around 70° in the metro area, keeping heat indices in check to around 100-103°. An afternoon shower or storm can’t be ruled out, but coverage should be sparse.

Tuesday could see a little more convective coverage as high pressure aloft begins to shunt southward a little, while Wednesday should be even a little more active as a trough approaches from the southwest and return flow from the Gulf establishes itself nicely with Atlantic high pressure retrograding eastward. Thursday and Friday feature more typical afternoon thunderstorm chances. Highs in this period will steadily head down, ranging from 94° on Tuesday to 90° on Friday. However, the infusion of humidity will keep heat indices in the low 100s through Thursday despite the lowering air temperatures.

Temperatures will continue to fall into the weekend, with highs stopping short of 90° expected Saturday and Sunday thanks to a little more in the way of onshore flow as Atlantic high pressure shifts a little more northward. This could also keep rain chances a touch higher, as well, but no washout is currently in the cards for the weekend. Overall, pretty standard early-August fare for the Charleston metro area.

Friday & the weekend: Traditional July fare to close the month

/ July 28, 2022 at 8:59 PM

We’ll stay hot heading into the last few days of July as ridging continues to feature prominently in the weather pattern. Temperatures will run in the low to mid-90s each day, with heat indices between 105-108° a distinct possibility during the height of each afternoon. Lows, meanwhile, will struggle below 80° away from the coast, with temperatures not getting below 80° at the beaches for the foreseeable future. Isolated thunderstorms appear possible each afternoon — it’s hard to avoid this time of year, but the risk for additional rain remains quite low overall. Where storms develop, pockets of locally heavy rain and gusty winds will be possible, but as mentioned, they’ll be quite sparse — a relatively quiet end to what’s been a rather unsettled month.

Heat continues through the weekend and into next week

/ July 27, 2022 at 5:58 PM

Another hot day is in store Thursday. After starting in the upper 70s away from the coast and Downtown (lower 80s there, gross), temperatures will warm to the mid-90s in the afternoon under partly cloudy skies. Mix in humidity and that’ll yield heat indices around 106°, plenty warm enough for heat exhaustion concerns during the peak of the afternoon. Much like today, expect rain-free conditions to persist as high pressure and the surface and aloft keep thunderstorm development at bay. Indeed, the only relief may be a cumulus cloud or two blocking out a bit of sun for a time.

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Rest of the work week: Getting hot in here

/ July 26, 2022 at 9:44 PM

We’ll be closing out the last work week of July with a good bit of heat as high pressure dominates the weather pattern. Air temperatures will run into the mid-90s each afternoon, while humidity on top will make it feel well into the mid-100s. While heat indices will not reach the post-July 1 heat advisory criteria of 110°, it’ll still be enough to elevate the risk of heat-related illness. Make sure you’re getting plenty of fluids and taking plenty of shady breaks during the heat of the afternoon if you must be outdoors. Low temperatures will run quite warm as well, only bottoming out in the upper 70s away from the coast. Downtown and coastal communities may not see lows dip below 80° for several days. This lack of any real cooling off can add to cumulative heat stress over time.

The aforementioned high pressure will keep afternoon showers and thunderstorms to a minimum, with only isolated coverage expected along and ahead of the seabreeze on Wednesday and Thursday, with unmentionably low rain chances on Friday. It’s hard to stay totally rain-free this time of year, but don’t expect much out of storms over the next few days.

Tuesday turns warmer; storms less prevalent

/ July 25, 2022 at 6:12 PM

We saw a lot less rainfall across the area today as ridging began to take hold. This continues into tomorrow and for much of the rest of the week as high pressure strengthens and maintains its grip. Highs will top out in the low 90s; mix in some humidity and you’ve got yourself heat indices in the low 100s.

Rain-wise, there’s not too much to write home about: We’ll have a shot at a shower or storm or two in the morning along the coast, but much of that activity should remain largely offshore. An isolated storm or two cannot be totally ruled out in the afternoon; where a storm fires, the rain could turn heavy and winds could be briefly gusty. However, the vast majority of us should stay dry. Expect this pattern to largely repeat itself for the rest of the work week, too, just with warmer air temperatures contributing to heat indices eventually reaching 105-110° by Wednesday and Thursday.