An inland trough of low pressure and sea breeze circulation helped produce strong/severe multi-cell thunderstorms within a warm and moist environment.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CHS wrote it up.
An inland trough of low pressure and sea breeze circulation helped produce strong/severe multi-cell thunderstorms within a warm and moist environment.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Charleston, SC wrote its last area forecast discussion before the first event at Aug 9, 3:12 PM EST, 1 hour 58 minutes earlier.
Area Forecast Discussion National Weather Service Charleston SC 412 PM EDT Thu Aug 9 2018 .SYNOPSIS... Inland low pressure will persist into next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Into Thursday evening: Multicell convection will continue along the I-16 corridor. Given MLCAPE values as high as 3000 J/KG and downdraft CAPE values exceeding 1000 J/KG in this area we will continue to assess the potential for isolated pulse severe/ brief damaging winds in this area. Meanwhile, isolated to scattered thunderstorms developing upstream will push into the region from inland/west toward the coast/east into the evening. Cannot rule out an isolated/brief severe thunderstorm with damaging wind gusts north of I-16 but the probability for severe weather will remain low. Also of note, the sea breeze will remain pinned near the coast, and isolated pulse thunderstorms will develop/dissipate near this boundary over coastal counties and adjacent coastal waters. This could enhance the potential for cloud to ground lightning at the beaches and adjacent waters. Later Thursday evening through the overnight: Multicell thunderstorms could continue to push into the region from inland locations well into the evening, but latest guidance suggests that overall coverage will gradually wane. Not long after midnight, PoPs fall to less than 15 percent with no explicit mention of showers/thunderstorms over land. Even near the coast, the land breeze/associated offshore flow should hold any overnight convection off the coast. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... The weather pattern becomes more unsettled across the Southeast. The mid-levels consist of broad high pressure centered in the southern Gulf of Mexico Friday. This high will slowly drift northward into Sunday. Meanwhile, a weak trough will be over the MS Valley Friday morning, moving eastward and passing over or just to our north Saturday morning. Then, a elongated low forms to our north Saturday and persist into Sunday. At the surface, a combination of troughing, low pressure, and a stationary front will be to our west during the short term. The interaction/development/dissipation of these surface features with the mid-levels will drive the weather each day. Though, the mesoscale details will be somewhat complex. We're generally forecasting chance POPs each afternoon. Though, Saturday and Sunday appear to be the more active days. PWATs hover around 2". Instability is more typical of mid-August values. So afternoon/evening showers and thunderstorms are a good bet. Given the atmospheric setup, severe storms (especially this weekend) with damaging winds cannot be ruled out. By the details are too hard to pin down at this point and will be best defined as the forecast rolls into the near term. Both high and low temperatures will be about 2-3 degrees above normal. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A cutoff low over the Midwest will dip southward early next week, making its closest approach to our area Monday into Tuesday. High pressure sliding into its more climatologically normal position to our east will turn low level flow more southwesterly during this time, and low level moisture will surge, with PWats over 2 inches. This, in combination with a series of shortwaves that will pivot around the southern periphery of the afore mentioned upper low will result in continued unsettled weather for the early part of the week. By midweek, the upper low will shift towards the Northeast and ridging will reestablish locally, ushering in a warmer and drier pattern. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... Expect thunderstorms in the KSAV vicinity into early evening. Expect amendments to account for direct thunderstorm impacts as this situation evolves. The chance for thunderstorms in the KCHS vicinity appears much more uncertain, and no mention of thunderstorms is justified through the 18Z TAF period. Outside any thunderstorms, expect VFR through the 18Z TAF period. Extended Aviation Outlook: Brief flight restrictions are possible in afternoon/evening showers/thunderstorms. Otherwise, VFR. && .MARINE... Tonight: The sea breeze will give way to enhanced SW winds as high as 15-20 kt, then winds will veer back to the west and will diminish somewhat by dawn. Seas of 2-3 feet will prevail, although seas as high as 4 feet could develop tonight beyond 20 nm. Given the west/offshore flow, thunderstorms over land could push into coastal waters and produce locally hazardous conditions, especially through this evening. The weather pattern becomes more unsettled across the Southeast as low pressure persists inland. The marine side can expect mostly SW winds. Winds could become gusty near the coast with the sea breeze each afternoon. Seas will average 2-3 ft through Saturday, then 2-4 ft Sunday onward. && .TIDES/COASTAL FLOODING... A Perigean Spring Tide will contribute to elevated high tide levels into early next week. The evening high tides could produce minor coastal flooding, mainly Friday into Mon. Thus, Coastal Flood Advisories are possible. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && NEAR TERM...SPR SHORT TERM...MS LONG TERM...CEB/MS AVIATION...MS/SPR MARINE...MS/SPR TIDES/COASTAL FLOODING...MS
Hazardous Weather Outlook National Weather Service Charleston SC 347 PM EDT Thu Aug 9 2018 AMZ330-350-352-354-374-GAZ087-088-099>101-114>116-118-137-138-140- SCZ040-042>045-047-052-102000- Charleston Harbor- Waters from South Santee River to Edisto Beach SC out 20 NM- Waters from Edisto Beach SC to Savannah GA out 20 NM- Waters from Savannah GA to Altamaha Sound GA out 20 NM, including Grays Reef National Marine Sanctuary- Waters from Savannah GA to Altamaha Sound GA extending from 20 to 60 NM-Jenkins-Screven-Candler-Bulloch-Effingham-Tattnall-Evans- Inland Bryan-Inland Chatham-Long-Inland Liberty-Inland McIntosh- Allendale-Hampton-Inland Colleton-Dorchester-Inland Berkeley- Inland Jasper-Tidal Berkeley- 347 PM EDT Thu Aug 9 2018 This Hazardous Weather Outlook is for Atlantic coastal waters, southeast Georgia and southeast South Carolina. .DAY ONE...This afternoon and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter assistance is not anticipated at this time. GAZ117-119-139-141-SCZ048>051-102000- Coastal Bryan-Coastal Chatham-Coastal Liberty-Coastal McIntosh- Beaufort-Coastal Colleton-Charleston-Coastal Jasper- 347 PM EDT Thu Aug 9 2018 This Hazardous Weather Outlook is for southeast Georgia and southeast South Carolina. .DAY ONE...This afternoon and tonight. There is a low probability for widespread hazardous weather. .DAYS TWO THROUGH SEVEN...Friday through Wednesday. Coastal Flooding: Astronomical factors and winds turning somewhat onshore each evening will lead to elevated tides through the weekend. Minor coastal flooding is possible with the evening high tides, mainly Friday into Monday. Coastal Flood Advisories may be needed. .SPOTTER INFORMATION STATEMENT... Spotter assistance is not anticipated at this time.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHARLESTON SC
609 PM EDT THU AUG 09 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0549 PM TSTM WND DMG 1 SSW MILLHAVEN 32.92N 81.66W
08/09/2018 SCREVEN GA 911 CALL CENTER
SCREVEN COUNTY 911 CENTER REPORTED A TREE DOWN ALONG
MILLHAVEN ROAD NEAR THE JOHNSON GROVE ROAD INTERSECTION.
TIME OF EVENT WAS ESTIMATED FROM RADAR DATA.
&&
EVENT NUMBER CHS1800700
SPRThe Charleston,SC radar (KCLX), 70 km away, was scanning. The volume nearest the first event began at 22:07 UTC.
29 thunderstorm wind, 1 lightning. Local standard time, as filed.
The public reported two large trees uprooted. The trees were healthy and 30-40 feet tall.
An emergency manager reported minor damage to a county building.
An emergency manager reported a tree down and across both lanes of Mixon Corner Road.
The South Carolina Highway Patrol reported a tree down in the 1200 block of Penny Creek Drive.
The South Carolina Highway Patrol reported a tree down in the 2300 block of Hendersonville Highway and U.S. 17 Alternate.
A trained spotter reported multiple trees down on Ivanhoe Road.
The Colleton County Fire and Rescue reported a large tree down and blocking all four lanes of South Jefferies Boulevard.
A trained spotter reported a tree down on U.S. 17 North Alternate.
The South Carolina Highway Patrol reported 2 trees down on Interstate 95. One tree was down near mile marker 53 northbound and the other was down between mile markers 54 and 55.
The South Carolina Highway Patrol reported a tree down in the 2000 block of Bells Highway.
The South Carolina Highway Patrol reported a tree down in the 2200 block of Green Pond Highway.
The South Carolina Highway Patrol reported a tree down on Highway 303 near Rivers Street.
The South Carolina Highway Patrol reported a tree down on Highway 64 about one half mile from Rodeo Drive.
The South Carolina Highway Patrol reported a tree down on Highway 15 near Wire Road.
The South Carolina Highway Patrol reported a tree down on Charleston Highway near the intersection with Saint Peters Road.
The South Carolina Highway Patrol reported a tree down on Jacksonboro Road near the intersection with Bodison Memorial Drive.
The Colleton County Fire and Rescue reported a tree down on a house near the 10400 block of Cottageville Highway. One person sustained minor injuries as the tree went through the house.
The South Carolina Highway Patrol reported a tree down on Peirce Road between Elf Jac Way and McDanieltown Road.
The South Carolina Highway Patrol reported a tree down on Highway 17 Alternate near Clubhouse Road.
The Dorchester County 911 Call Center reported a tree down along Highway 61 near the intersection with Bacons Bridge Road.
The Charleston County 911 Call Center reported a tree down along Salters Hill Road near Hollywood.
The South Carolina Highway Patrol reported a tree down near 8600 Moffett Road.
The Charleston County 911 Call Center reported a tree down on power lines near the intersection of County Line Road and Hyde Park Road.
The Dorchester 911 Call Center reported a tree blown down on Dorchester Road near Wescott Park.
A 5 inch diameter tree limb fell on a driveway in Boltons Landing Subdivision in West Ashley.
The public reported a tree and power line down in Summerville near Gahagan Park.
The media reported a tree down beside a house on Opal Avenue.
A trained spotter reported a tree down and blocking the road near the intersection of Benson Street and Huger Street.
The media reported a large tree down on a house in the area of Blakeway Street and Schooner Street. The house sustained roof damage and water damage to a second floor room.
The police reported a tree down and blocking part of the road on U.S. Highway 17 near the intersection with Mathis Ferry Road in Mount Pleasant.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Carolina in 2018Every state in 2018This day in weather historyWarnings in South Carolina, August 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 780405, 780681, 780406, 780682, 780683, 780686, 780687, 780688, 780689, 780690, 780691, 780698, 780699, 780700, 780701, 780702, 780703, 780705, 780707, 780708, 780709, 780710, 780711, 780712, 780713, 780715, 780716, 781059, 781061, 781064.