River levels already high from excessive rains during late June received another push upward from heavy rainfall on July 1. Rainfall from one to two inches was common upstream in the basin.
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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 FSD wrote it up.
River levels already high from excessive rains during late June received another push upward from heavy rainfall on July 1. Rainfall from one to two inches was common upstream in the basin.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Jul 2, 2:01 PM CST, 2 hours 59 minutes earlier.
Area Forecast Discussion National Weather Service Sioux Falls SD 301 PM CDT Mon Jul 2 2018 .SHORT TERM...(This evening through Tuesday) Issued at 300 PM CDT Mon Jul 2 2018 Quasi-stationary front remains draped across central South Dakota early this afternoon. Temperatures continue to heat into the 80s and lower 90s, with dewpoints in the mid 60s. The strongest shear and instability remain across south central SD in our forecast area, however capping remains quite problematic throughout the region. Closer to the front in central and northeast SD, the capping is weakest, however the question will be whether the cap can weaken enough near our western border for storms to initial in our forecast area. Seeing some scattered cumulus forming in this area, however there is no sign of any upward growth. The low level jet does increase this evening into the early morning hours and could help aid storm develop in our extreme western counties, however right now stronger LLJ convergence will be across northeast SD outside of the forecast area. CAMS continue to struggle in producing convection even in south central, and what does develop, rapidly diminishes by mid to late evening. Bulk shear profiles reach around 35 to 40 kt in south central/east central, but decrease heading east and south, while DCAPE values above 1000 j/kg. If storms do manage to develop this evening in south central (west of the James), severe storms will be possible with hail and damaging wind threats. Elsewhere, severe weather is unlikely. Heat and humidity continue to build into midweek, with dewpoints surging into the low to mid 70s by Tuesday afternoon. Breezy southerly winds and partly cloudy skies will lead to highs in the mid 80s to lower 90s. Weak quasi-stationary frontal boundary is expected to remain northwest of the forecast area, with precipitation expected to hold off during the daytime. .LONG TERM...(Tuesday night through Monday) Issued at 300 PM CDT Mon Jul 2 2018 Frontal boundary shows very little movement across central through northeast SD into Tuesday night. Low level jet increases once again across central and northeast SD and will be the likely focal point for thunderstorm activity. The better chance for precipitation will be outside of the forecast area, however will leave a chance mainly in south central and the highway 14 corridor Tuesday night. Shear looks fairly weak across the area and decreases further south, thus the severe threat is fairly low. Hot and humid conditions continue into Independence day. Surface low and stationary boundary finally begin advancing eastward in the afternoon. With dewpoints rising into the lower to mid 70s once again, and temperatures reaching the upper 80s to lower 90s, we'll likely see heat index values reach 100 to 105. The worst conditions will be where temperatures will be hottest, mainly in far southeast SD, northeast NE, and northwest IA in the afternoon. Will likely need heat advisory headlines in the future. Isolated elevated showers and thunderstorms are expected to develop by Wednesday afternoon, with chances increasing into the evening with the advancing front. Shear profiles remain quite weak with this system, which will great limit any severe threat. Cooler temperatures return behind the exiting system, for the second half of the week. Surface high pressure slides through the region, with upper level ridging gradually rebuilding over the Plains into Saturday. This will keep the forecast dry with highs in the 80s. A wave attempts to flatten the ridge early next week, potentially bring the next chance of thunderstorms. Still seeing some uncertainty into the strength and track of the wave. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1209 PM CDT Mon Jul 2 2018 VFR conditions are expected through the TAF period. There will be a low chance of thunderstorms developing after 00z and continuing overnight, mainly across east central through south central SD. Have mentioned VCTS in the HON TAF, however chances further east are too low for mention. Strong low level jet this evening and overnight will lead to low level wind shear concerns at all TAF sites. Shear conditions improve after 12z. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM... LONG TERM... AVIATION...
Hazardous Weather Outlook National Weather Service Sioux Falls SD 516 AM CDT Mon Jul 2 2018 IAZ002-003-012>014-020>022-031-032-MNZ090-NEZ013-014-SDZ071- 031030- Osceola-Dickinson-Sioux-O'Brien-Clay IA-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Jackson-Dixon-Dakota-Union- 516 AM CDT Mon Jul 2 2018 This Hazardous Weather Outlook is for portions of northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, and southeast South Dakota. .DAY ONE...Today and Tonight Moderate to major flooding will continue on many rivers. Those with interest along area rivers will want to remain alert. For specific river details, visit: https://water.weather.gov. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Heat indices will climb to near 100 Wednesday afternoon. There is a chance of thunderstorms Wednesday night. A few of the storms may be strong producing strong winds and hail. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. IAZ001-MNZ080-081-089-097-098-SDZ056-060>062-065>070-031030- Lyon IA-Murray-Cottonwood-Nobles-Pipestone-Rock-Moody-Hanson- McCook-Minnehaha-Hutchinson-Turner-Lincoln SD-Bon Homme-Yankton- Clay SD- 516 AM CDT Mon Jul 2 2018 This Hazardous Weather Outlook is for portions of northwest Iowa, southwest Minnesota, east central South Dakota, and southeast South Dakota. .DAY ONE...Today and Tonight There is a slight chance of thunderstorms Monday night into Tuesday morning. These storms are not expected to be severe. Minor to moderate flooding will continue on some rivers, especially the Vermillion and Big Sioux. Those with interest along area rivers will want to remain alert. For specific river details, visit: https://water.weather.gov. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Thunderstorms are possible across the region Tuesday night. These storms are not expected to be severe. Additional storms are possible Wednesday night. A few of these storms may be strong producing strong winds or large hail. Heat and humidity will increase across the region creating heat indices near 100 Wednesday afternoon. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated. MNZ071-072-SDZ038>040-050-052>055-057>059-063-064-031030- Lincoln MN-Lyon MN-Beadle-Kingsbury-Brookings-Gregory-Jerauld- Sanborn-Miner-Lake-Brule-Aurora-Davison-Charles Mix-Douglas- 516 AM CDT Mon Jul 2 2018 This Hazardous Weather Outlook is for portions of southwest Minnesota, central South Dakota, east central South Dakota, south central South Dakota, and southeast South Dakota. .DAY ONE...Today and Tonight Thunderstorms are possible Monday evening into the overnight. A few storms may be strong to severe producing large hail up to the size of ping pong balls and damaging winds up to 60 mph. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Heat indices will approach 100 degrees Tuesday and Wednesday afternoon. Thunderstorms are once again possible Tuesday and Wednesday evenings into the overnight hours. A few storms may be strong producing large hail and damaging winds. .SPOTTER INFORMATION STATEMENT... Spotter activation is possible after 4 PM today.
The national radar mosaic for the moment the first event began.
4 flood. Local standard time, as filed.
Crop and pasture land near the Big Sioux River was impacted as river levels climbed to 1.0 feet above flood stage near Sioux Falls at Interstate 90 (gage site SFLS2).
Crop and pasture land near the Big Sioux River was impacted as river levels climbed to 0.6 feet above flood stage near Brandon (gage site BBSS2) on July 3.
Crop and pasture land near the Big Sioux River was impacted as river levels climbed to 0.6 feet above flood stage near Brandon (gage site BBSS2) on July 3.
Crop and pasture land near the Big Sioux River was impacted as river levels climbed to 0.4 feet above flood stage near Canton (gage site CBSS2) on July 4.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2018Every state in 2018This day in weather historyWarnings in South Dakota, July 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: 772482, 772480, 772481, 755056.