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Author: Jared Smith

Jared Smith founded @chswx on Twitter in 2008 as an experiment in disseminating weather data through social media. In the ensuing decade-and-a-half, @chswx has provided live coverage of tropical cyclones, tornadoes, severe weather, and even a couple bouts of winter weather to the good people of Charleston, SC.

The week ahead: A climatologically normal last week of July

/ July 23, 2023 at 10:29 PM

Believe it or not, it’s already the last full week of July. Climatologically speaking, this week’s forecast is about as end-of-July as it gets: Mid-70s lows each morning, low 90s highs each afternoon with isolated to scattered afternoon thunderstorm chances as the trough that made Sunday in particular quite unsettled lifts out and ridging begins to build back in.

Monday could offer up some slightly better shower and storm chances during the day as a little spin remains in the atmosphere, but a repeat of Sunday’s deluge (more on that in a minute) is certainly not in the cards with generally scattered coverage expected.

Mid-week will feature highs generally 92-93° with a few seabreeze showers and thunderstorms each afternoon in a very standard summertime regime with Atlantic ridging firmly in place. If anything, that will get even a little stronger as we head into the weekend; temperatures will respond appropriately by heading back into the mid-90s on Saturday and upper 90s on Sunday. Dewpoints won’t quite be as nasty as they were this past week, but low-70s dewpoints should still yield a period of heat indices 104-106°.

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Sunday’s forecast: Storms turning likely by evening

/ July 22, 2023 at 10:01 PM

Standard July warmth and mugginess will continue on Sunday. We’ll start the day in the mid-70s under partly cloudy skies, and we should get the first part of the day in rain-free. From there, we’ll start to see showers and thunderstorms develop by mid-afternoon and make their way into the area from the west and southwest throughout the rest of the evening. The strongest storms could produce strong wind gusts, while heavy rain and frequent lightning will be more widespread concerns. Be ready to bring outdoor activities inside if thunderstorms approach.

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Weekend forecast: Scattered storms, not quite as hot (but still hot)

/ July 21, 2023 at 7:53 PM

Air temperatures return to more reasonable levels for mid-July this weekend as a trough digs in a bit more, nudging the ridge that had brought us quite a hot stretch back to the west. It will also improve shower and thunderstorm chances across the area starting Saturday afternoon. Granted, it will still be humid, and heat indices on Saturday in particular will head back north of 100°, but not quite as high as we’ve seen the past few days. Showers and thunderstorms should fire in the afternoon and evening as disturbances round the base of the trough. One or two of these storms could produce strong wind gusts. Be ready for rapidly changing conditions, but don’t cancel any outdoor plans, either.

Sunday could be a little more active as another disturbance passes by. It could instigate scattered storms by midday, but they’ll be more likely in the afternoon. Again, not expecting a washout by any stretch, but be ready to bring outdoor plans inside if thunderstorms approach your location. Highs top out in the low 90s Sunday with heat indices approaching 100°.

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Friday & the weekend: Turning “cooler” with more in the way of storms

/ July 20, 2023 at 9:25 PM

We have one more really hot day on Friday, with heat indices well in excess of 105° expected one more time in the afternoon. A few 110° readings won’t be ruled out, either, and it’s possible another Heat Advisory will be needed as air temperatures head into the upper 90s.

Scattered afternoon thunderstorms will again figure into the forecast, and one or two of them could produce damaging downburst winds. There is a risk for more organized severe weather moving down the Savannah River Friday night. The degree to which we experience this will be largely determined by the position of the subtropical ridge, which should retrograde a little more westward by tomorrow evening, keeping the main threat to our southwest. We’ll watch it, though.

Heading into Saturday and Sunday, troughing combined with a weak front stalling out nearby will keep afternoon shower and thunderstorm chances in vogue. Temperatures won’t be quite as scorching as we’ve seen, though, with highs topping out only in the low 90s thanks to the lower heights aloft. This is closer to normal for this point in the year. Heat indices, however, will still run above 100° each afternoon, and could make a run for 105° on Saturday. Stay cool if you’re spending time outdoors, and be ready to bring outdoor activities inside in case thunderstorms threaten.

Thursday: Heat index approaches 110° across the metro before storms move in

/ July 19, 2023 at 10:10 PM

Thursday is going to be another hot day across the area. Expect to start the day just barely below 80° inland and likely a couple degrees above it closer to the coast. We’ll warm back into the mid-90s during the day, and with dewpoints not mixing out quite as much — expect them to hang around in the mid-70s — we should see heat indices peak around 110° or so in the afternoon. This is certainly well into the danger zone for heat illness, so please do take it easy if you must be outside. There’s no Heat Advisory as of this writing, but don’t be surprised if one is issued by morning.

Attention then turns to the potential for showers and thunderstorms to move into the area in the afternoon and evening courtesy of a disturbance rounding a retreating ridge of high pressure. Most of these storms should be efficient rainfall and lightning producers, and a few of these storms could be on the strong side with damaging wind gusts the main concern. Hail can’t be ruled out, either. Stay alert to rapidly changing conditions as we get into tomorrow afternoon and evening, and don’t be surprised if there are evening commute impacts.

Fortunately, wildfire smoke will play much less of a role in Thursday’s weather as it continues to disperse southward.

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Rest of the work week: Heat peaks with little in the way of relief

/ July 18, 2023 at 9:25 PM

We’ll continue this hot stretch of weather as we get into Wednesday and through the rest of the work week. Expect highs in the mid-to-upper 90s each afternoon with heat indices peaking around 105-110° each day in many spots, with perhaps even higher heat indices closer to the coast where the higher-dewpoint air will be found. Lows won’t offer much in the way of relief — generally expect just upper 70s across much of the metro, with temperatures not going below 80° downtown and at the beaches over the next few days. With drier air aloft, it’ll be hard to get much in the way of thunderstorms to fire along the pinned seabreeze, and they likely won’t be deep enough to really overturn the atmosphere much, possibly leaving even muggier conditions behind them.

Wildfire smoke will once again cloud the sky a little bit on Wednesday, but not quite to the degree that we saw on Tuesday. The air quality forecast is on the lower side of code yellow for Wednesday, but that seems to be primarily due to ozone. As always, we’ll keep an eye on this in case smoke mixes down a little more than expected.

Troughing digs back in across the area over the weekend, which will send temperatures downward and bring rain chances upward, breaking this mini-heat wave. (You either get the heat or storms this time of year — not really a third option!)

Tuesday’s forecast: Starting a hot stretch

/ July 17, 2023 at 10:12 PM

We begin a rather hot stretch of weather — yes, even warmer than we’ve been — starting Tuesday as ridging builds aloft. Downslope flow from the northwest will act to warm the air as it sinks as well as help to keep the seabreeze pinned closer to the coast, which will help drive air temperatures well into the mid-to-upper 90s across the area after an already warm start in the upper 70s to around 80° at the coast. Mix in humidity and you’ll find heat indices across the area ranging from about 105-110° during the height of the afternoon. We’ll be in this heat index “danger zone” for a few days, so be sure to take it easy if you have to be outdoors during this time, and get lots and lots of water.

As the ridge builds aloft, this will also help to put a lid on afternoon thunderstorms for the most part; a shower or storm can’t be totally ruled out, but don’t count on one for any sort of heat relief.

Finally, Canadian wildfire smoke will add a milky haze to the overall sky composition. Upstream observations suggest that there could be some minor air quality impacts, but so far no major issues are anticipated. Stay tuned, though.

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The week ahead: Ridging builds in, turning air temperatures up and storms down

/ July 16, 2023 at 10:20 PM

High pressure will ridge into the area for much of the new week ahead, sending air temperatures up and thunderstorm chances down before weakening into the weekend, bringing back a better chance of afternoon and evening showers and thunderstorms.

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Weekend forecast: Standard July heat, humidity, and scattered afternoon storms

/ July 14, 2023 at 8:13 PM

A fairly standard mid-July weekend lies ahead across the metro area. Highs top out in the low-to-mid-90s each day after starting out in the mid-to-upper 70s. The seabreeze will be the main instigator for afternoon and evening thunderstorms; as is customary for this point in the year, heavy rain and frequent lightning are the main threats, with gusty winds possible within the strongest storms. Severe or not, all thunderstorms are dangerous due to the lightning they produce. When thunder roars, go indoors.

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Friday & the weekend: Increasingly warm and stormy

/ July 13, 2023 at 5:57 PM

Friday and the weekend will feature another round of warm temperatures, with heat indices running 105-110° by the weekend, and a solid chance of thunderstorms each afternoon and evening. We’ll start each day in the upper 70s — perhaps not getting below 80° downtown and at the beaches — before warming to the mid-90s each afternoon. Surface dewpoints running solidly in the mid-70s will yield heat indices approaching 105° on Friday. The weekend should peak even hotter, with heat indices approaching 105-110° each afternoon. Stay tuned for the potential for Heat Advisories from the National Weather Service.

From there, showers and thunderstorms will fire each afternoon along and ahead of the seabreeze. Heavy rain and frequent lightning will be the main concerns, though the stronger updrafts found where outflow boundaries collide could be capable of producing a marginally severe storm or two with damaging wind gusts the main concern. As is often the case in July, it will not rain all day, and some of you may not see rain every day. Just be ready to bring outdoor activities inside in case thunderstorms approach. Severe or not, lightning makes every thunderstorm dangerous. “When thunder roars, go indoors!”