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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.

Hot and occasionally stormy weekend ahead

/ July 30, 2021 at 9:41 PM

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.

Heat indices exceeding 110° — possibly approaching 115° — possible Friday

/ July 29, 2021 at 6:43 PM

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!

Hottest stretch of 2021 thus far begins on Thursday

/ July 28, 2021 at 9:47 PM

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.

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Scattered storms with heavy rain today

/ at 7:52 AM

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.)

Periods of heavy rain expected Tuesday

/ July 26, 2021 at 9:04 PM

We’ve got a muggy and potentially soggy Tuesday ahead. While it won’t rain all day, expect plenty of shower and thunderstorm coverage to bring just about everyone some rain at some point tomorrow. Given plentiful tropical moisture, some of this rainfall could become quite heavy at times, leading to the potential for isolated bouts of flooding where the heaviest rain falls. Heavy rain will be possible possibly as soon as shortly after daybreak, similarly to today, as it likely won’t take much heating to start convection. We’ll want to watch the 11:18am high tide closely as high-resolution guidance suggests storms in the area around that time.

Temperatures will remain on the warm and muggy side. We’ll start in the upper 70s across much of the area, with 80° lows possible along the coast and in downtown Charleston. Highs will only top out in the upper 80s given the expected shower and thunderstorm coverage.

High rain chances continue into Wednesday before moisture departs and we heat up for Thursday and especially on Friday, which could be the hottest day of 2021 thus far if the forecast of 96° remains on track. Stay tuned.

The week ahead: Tropical moisture returns, then we turn hot

/ July 25, 2021 at 8:24 PM

After a very rare weekend of relatively low humidity (for late July, anyway) we’ll see dewpoints return to the low to mid-70s as tropical moisture builds back into the area. Monday will feature isolated showers and thunderstorms primarily driven by the seabreeze, but as we get into Tuesday and Wednesday, a low pressure system — labeled by the National Hurricane Center as Invest 90L with a 50% chance of tropical development — will be approaching the coastline as we get into mid-week. Regardless of what it ends up doing from a tropical standpoint, it will enhance our shower and thunderstorm chances Tuesday and Wednesday, particularly in the afternoons. Temperatures will top out in the low 90s each day.

As we get closer to the end of the week, the strong high pressure over the central US noses its way into the eastern US. This, in turn, will drive down rain chances and drive up temperatures. Temperatures should top out in the mid-90s Thursday and Friday.

Owing to just how “mild” this summer has actually been, the hottest it’s been this year is 94°, which we’ve reached three times (twice in May and last on June 15). If Friday’s forecast of 96° verifies, that will be the warmest we’ve been all year.

By the weekend, we could see an uptick again in showers and thunderstorms as the ridge backs off a little bit and we get underneath some northwest flow aloft. NWS noted in its afternoon discussion that this could open up the pathway for summer thunderstorm complexes — the technical term for which is “mesoscale convective system” — to roar through the area starting this weekend. Something to watch, but nothing we need to be overly concerned about right now.

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Friday and the weekend: Drier with the right amount of July heat

/ July 22, 2021 at 10:38 PM

After another day of very heavy rain in the Charleston metro area — this time in West Ashley — we mercifully get Friday and the weekend to dry out a little bit as a front sags south of the area, turning winds to the east and northeast. This will keep temperatures right around, if not slightly below, late July normals. Heat indices will even be reasonably in check — upper 90s on Friday, but down to the mid-90s for Saturday and Sunday.

With the drier air comes a little less cloud cover and far lower shower and thunderstorm chances (though I suppose you can never totally rule out an afternoon shower or storm in late July). Wildfire smoke transported all the way from the western U.S. looks to filter into the area starting tonight and will last for the next few days. This will make for some interesting sunrises and sunsets. It doesn’t look like this smoke will be close enough to the ground to cause any major air quality impacts, at least right now. We’ll keep an eye on this in case it changes, but for now, good air quality is in the forecast for Friday.

We’ll also want to keep an eye on the risk for salt water flooding with the evening high tides this weekend. Onshore flow will combine with astronomical influences to produce a few rounds of sunny-day flooding through at least Sunday. Be ready for coastal flood advisories and possibly some closed roads due to salt water on the roads. Fortunately, we don’t look to have much if any rain on top, mitigating a more serious flooding issue.

All in all, it’ll be a pretty good July weekend — I hope you can take advantage.

Warm day yields to scattered showers and storms this afternoon; heavy rain, flooding possible

/ at 8:34 AM

We start this Thursday with temperatures already approaching 80° as of 8am. Highs around 90° look to be common before showers and thunderstorms erupt this afternoon.

Today’s setup could portend a flooding event in downtown Charleston this afternoon and evening. Westerly winds look to pin the seabreeze closer to the coast, and with a front advancing from the north, there will be numerous focal points for showers and thunderstorms to develop. Atmospheric moisture is readily available, with precipitable water values running over 2″ once again today (anything 2″ or over generally requires more scrutiny for flooding). Finally, we are in a king tide period, and this morning’s thinking from NWS on tonight’s high tide is that it will fall just short of the 7′ level at which sunny-day salt water flooding typically begins. (It may yet be high enough, though, to begin to produce some flooding on Fishburne and Hagood.)

Guidance suggests that showers and thunderstorms generally should start to form between 1-3 PM. Storm motions will approach the coastline today, and with a seabreeze trying to push the opposite direction, this certainly invites concern about heavy rainfall stalling out for a period of time. The high-resolution model ensemble this morning once again paints a 30% chance of 3″ of rain in 3 hours across the metro area this evening, further lending credence to this concern. While this isn’t a slam dunk, it’s important to keep an eye on the weather today as impacts to the evening commute are certainly in the cards. More on this later today — stay tuned.

Rest of the work week: Warming up with scattered storms

/ July 20, 2021 at 8:40 PM

We’ll get back into a warming trend for the rest of the work week as the mid-level trough that’s been keeping us quite unsettled yields to a little more ridging over the next few days. This will, in turn, help suppress the more widespread shower and thunderstorm development we’ve seen to start the week. Expect scattered showers and thunderstorms primarily each afternoon as daytime heating and the seabreeze kick in. Heavy rain will be possible within the strongest storms, particularly on Wednesday as deep tropical moisture remains in place. We’ll see this deeper moisture shunted a little further south getting into Thursday and Friday, cutting the heavy rain threat a little bit more, but it’s summer — an isolated downpour or two just cannot be ruled out.

As mentioned earlier, temperatures are going to warm up, and we’ll be back into the low 90s by Thursday. Mix in some humidity and it’s going to feel like the low 100s, so make sure you’re getting enough water and shade if you’re outdoors in the peak of the afternoon.

Heavy rain and isolated bouts of flooding possible again this evening

/ at 8:23 AM

We look to have another wet day ahead, with some showers already popping up west of the Ashley as I write this. The best chance for showers and thunderstorms will again be later this afternoon into this evening. There will once again be a chance for localized heavy rain, with a 30% probability of 3” of rain in 3 hours once again being indicated by the high-resolution ensemble data. Yesterday this bore out in the 17-A corridor headed into College Park, with floodwater on the ground for a few hours after the main rain event. Thus, we are going to need to watch radar trends carefully, noting that high tide will be coming up at 5:39 PM.

Clouds and rain will keep temperatures a few degrees below normal, with highs in the mid-80s expected across the area. A few peeks of sun aren’t out of the question, allowing temperatures in a few spots to perhaps jump quickly. Humidity will still factor in, though, and it’ll feel closer to 94-95° in the afternoon.

Try to stay dry and weather-aware once again today!