Charleston Weather Blog

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

A little more persistent cloud cover for Tuesday

/ March 22, 2021 at 8:50 PM

Cloud cover will look to be a bit more persistent on Tuesday, once again keeping temperatures right around 70° in the afternoon with low pressure stuck offshore, roughly about where the NC and SC border would be. Conditions should remain rain-free throughout the day, and we should get the sun peeking in and out as well.

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The week ahead: Getting warmer, with scattered storms mixing in

/ March 21, 2021 at 10:28 PM

We’ll be warming up as the week goes on — the last full week of March, already! — with isolated to scattered showers and storms possible beginning Tuesday night. The next significant storm system on the docket is expected to arrive sometime Thursday or Friday, but persistent low pressure keeps rain chances in the picture well before that.

Gusty winds will continue overnight into Monday, with 30-40 MPH gusts possible near the coast and on bridges. This is due to a tight pressure gradient between a wedge of high pressure inland and a surface low migrating northeastward off the coast. Northeast winds look to relax a little on Tuesday, but could still be gusty at times near the coast. A High Surf Advisory and a High Risk of Rip Currents is in effect for Monday — not a great beach day, for sure.

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Friday & the weekend: The wedge returns

/ March 18, 2021 at 7:23 PM

We’ll get Friday off to a nice start in the wake of the cold front which instigated a lot of the rough weather over the last couple days in the eastern half of the country. Temperatures will start around 50-51° under mostly clear skies. We’ll warm to the mid-60s before another cold front “backdoors” in from the north, bringing much cooler temperatures and a return to cloud cover.

Yes, folks…the wedge is back.

Saturday will start out much cooler than normal, with highs in the upper 30s. Temperatures will only head up to the mid-50s as the wedge settles in. At the same time, a low will spin up off the Florida and Georgia coast. Convergence on the northern half of the low could help spread a few showers into the area as early as Saturday, but slightly better rain chances arrive on Sunday as the low heads northeast, coming a little bit closer to our coastline. Sunday looks a bit warmer with highs near 60° as the wedge seems to weaken a little bit. Don’t fret — we’re back in the 70s by next Tuesday.

Tornado watch has expired

/ at 11:50 AM

UPDATE 6:00 PM: The National Weather Service has canceled the tornado watch. The risk for severe weather has ended across the Lowcountry.

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Today’s severe weather threat: Updated timing and impacts

/ at 8:09 AM

Today could feature a severe weather episode across the Lowcountry in the afternoon and early evening hours as a squall line pushes through the area. Damaging straight-line wind gusts are the primary concern, but embedded strong tornadoes and some large hail will be possible as well. We may see some weakening of the storms as they approach the Charleston metro area as the line interacts with a more stable marine layer, but I wouldn’t hang my hat on it as these storms could remain vigorous enough to overcome the stable air.

Before the storms arrive, expect mostly cloudy skies with some peeks of sun. Highs should top out in the upper 70s provided the line does not sweep through earlier than anticipated. It’ll turn windy outside of thunderstorms as the low-level jet kicks up throughout the day. Gusts to 30+ MPH will be possible, making bridge driving a little more tricky.

Storms should clear the area by around 6-7 PM if current timings hold, and we will turn much cooler tomorrow.

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Strong to severe storms may become widespread ahead of a cold front Thursday

/ March 17, 2021 at 6:07 PM

Severe weather appears to be in the cards for Thursday as a cold front approaches the area in the afternoon and early evening hours. This cold front is expected to be bringing a squall line with it, and the atmosphere ahead of the line will become increasingly favorable for sustaining severe weather. Temperatures will surge to near 80° especially away from the immediate coast before being tamped down later in the day. Even outside of thunderstorms, it will be windy, with gusts 30-40 MPH possible thanks to a strengthening low-level jet, which will help contribute to increased shear to help organize severe thunderstorms.

The squall line is the main concern, though. The line could enter western portions of the Tri-County as early as 1-2 PM, and may exit as late as 8 PM, based on the National Weather Service’s latest timing estimates. The line is slowly starting to take shape across Louisiana, and we will want to watch its progress closely over the next 24 hours to ensure timing and forecast is on track. A somewhat later arrival could mean more time for the atmosphere to destabilize, increasing the severe weather threat.

Hazards with the line include the risk for widespread damaging straight-line winds as well as a few tornadoes — a couple of which could be on the strong side, particularly near the I-95 corridor. Quarter-size hail is a possibility as well. Additionally, while not explicitly modeled in our area, we’ll want to keep an eye on any storms that might try to get going ahead of the line as those could pose a higher tornado risk.

Finally, it’s most important to note that not all of you will see severe weather tomorrow. There are limiting factors at play, including the role that the cooler Atlantic shelf waters may play in stabilizing the atmosphere closer to the coast and just how unstable the atmosphere can ultimately get here due to cloud cover. Severe weather forecasts are rarely a slam dunk in the Lowcountry because of our unique geography. With all that said, though, let’s be ready for the worst, but hopeful for a relatively quiet day.

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Wednesday: Some calm before Thursday’s storms

/ March 16, 2021 at 9:56 PM

Another round of rain is expected overnight tonight as an upper-level disturbance moves through, with isolated showers possible during the day Wednesday.

The high pressure wedge won the day today, keeping temperatures well below forecasted levels in the low to mid-60s in the Charleston metro, while Moncks Corner struggled to 50°. It appears that the wedge will once again put a dent in temperatures tomorrow, with highs in the upper 60s in the Charleston metro perhaps being a bit generous if this afternoon’s high-resolution model runs have anything to say about it. Bottom line: Don’t misplace the light jacket tomorrow, preferably the green one given St. Patrick’s Day.

While we’ll be relatively calm tomorrow, a severe weather outbreak is expected from western Tennessee to Alabama as a strong storm system moves across the Mid-South. This storm system will head eastward and play a potentially major part in our weather on Thursday.

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