A deep warm cloud layer and weak steering flow resulted in persistent and slow-moving showers and thunderstorms. Rainfall from Brule to Sanborn and Beadle Counties generally ranged from 3 to 5 inches during the morning and mid-day hours.
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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.
A deep warm cloud layer and weak steering flow resulted in persistent and slow-moving showers and thunderstorms. Rainfall from Brule to Sanborn and Beadle Counties generally ranged from 3 to 5 inches during the morning and mid-day hours.
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 Aug 2, 11:16 AM CST, 29 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1216 PM CDT Fri Aug 2 2019 .UPDATE... Issued at 1157 AM CDT Fri Aug 2 2019 A moist atmosphere characterized by PWATs approaching 2 inches near/west of the James River, along with a deep warm cloud layer depth has resulted in very efficient rainfall across western portions of the FA. Gauge reports form both Chamberlain and Huron indicate rainfall over 2-3 inches with a spotter report of over 4 inches near Chamberlain. Area webcams have also shown ponding of water in fields. Considered a Flood Watch earlier this morning but given the ongoing nature of the event, will continue to cover the threat with more localized Flood Warnings. Model guidance has struggled with the eastward progression of this activity but current moisture transport vectors would suggest the heaviest rainfall generally should stay near/west of a Wagner to Mitchell to De Smet line with lighter more hit or miss activity to the east. Some locations west of the previously mentioned line may pick up an additional 2 or more inches or rain. && .SHORT TERM...(Today and Tonight) Issued at 351 AM CDT Fri Aug 2 2019 Mid/upper level energy drifting out of the Northern Rockies has produced scattered showers and isolated thunder west of Interstate 29 early this morning, though rainfall measurement has been hard to come by with low level dry air in place. This will remain the theme for the day as the shortwave slides eastward - with the better rain chances remaining in our western CWA - with strong high pressure residing over the Upper Mississippi Valley and increasingly drier air toward the east. With a strong moisture fetch into our western zones, a weak midlevel flow, and model PWAT values approaching 2" over that area, cannot rule out brief heavy rain, especially early in the day, and a WPC Marginal Risk for excessive rainfall seems appropriate. Instability is weak, so no severe storms are expected, and in fact lightning has been next to non existent over our area overnight. With abundant cloud cover remaining for much of the day, temperatures will be held down a bit with highs mainly mid to upper 70s. Any rainfall begins to taper off tonight as strengthening high pressure expands westward. With that, winds will become nearly calm, and if we can get some clearing areas of fog will be a possibility. Lows tonight will be in the lower to mid 60s. .LONG TERM...(Saturday through Thursday) Issued at 351 AM CDT Fri Aug 2 2019 By Saturday, upper level riding oriented over the western CONUS begins to build eastward, resulting in a drying trend and warmer temperatures into the beginning of next week. This will play out to highs into the mid and upper 80s by Sunday. Models still indicating a frontal passage for Monday and Monday night, which will bring increasing thunderstorm chances during that time frame, and usher in slightly cooler temperatures that will linger into the middle of next week. && .AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon) Issued at 1157 AM CDT Fri Aug 2 2019 Primary concern in the near term is the ongoing heavy rain/embedded thunder across areas near and west of the James River including KHON. This has resulted in IFR ceilings/vsby at times. Guidance has struggled with the eastward progression of this activity but current thinking is that the bulk of the precipitation will remain west of KFSD/KSUX this afternoon/evening with just lighter hit or miss showers working thru those terminals at times. Next period of potential concern comes later tonight into Saturday morning. Some of the latest guidance hints at additional precipitation development after midnight with the NAM furthest east along the I-29 corridor. Confidence in these solutions is quite low given their lack of run to run and model to model consistency so will not include mention in the TAF at this time. If this were to materialize, could see some lower ceilings in this activity. Previous guidance suggested more of a clearing trend which would have resulted in some fog threat, which still cannot completely discount. Overall, a fairly muddled forecast. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && UPDATE...Kalin SHORT TERM...JM LONG TERM...JM AVIATION...Kalin
Hazardous Weather Outlook National Weather Service Sioux Falls SD 410 AM CDT Fri Aug 2 2019 NEZ013-014-SDZ038>040-050-052>071-030915- Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory-Jerauld-Sanborn- Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-Minnehaha- Charles Mix-Douglas-Hutchinson-Turner-Lincoln-Bon Homme-Yankton-Clay- Union- 410 AM CDT Fri Aug 2 2019 This Hazardous Weather Outlook is for northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. Scattered showers and thunderstorms will be possible across the area through this evening. While severe storms are not expected, brief locally heavy rain is possible, mainly over south central SD and the James River Valley. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-030915- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock- 410 AM CDT Fri Aug 2 2019 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa and southwest Minnesota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1023 AM CDT FRI AUG 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1020 AM HEAVY RAIN 5 S CHAMBERLAIN 43.73N 99.31W
08/02/2019 M2.50 INCH BRULE SD CO-OP OBSERVER
2.5 INCHES OF RAIN HAS FALLEN IN THE LAST 30
MINUTES, WITH RAIN CONTINUING TO FALL.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1137 AM CDT FRI AUG 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1137 AM HEAVY RAIN 5 S CHAMBERLAIN 43.73N 99.31W
08/02/2019 M4.45 INCH BRULE SD CO-OP OBSERVER
90 MINUTE STORM TOTAL, THIS INCLUDES THE 2.5
INCHES REPORTED EARLIER.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1212 PM CDT FRI AUG 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1200 PM HEAVY RAIN 3 S CHAMBERLAIN 43.77N 99.32W
08/02/2019 M3.05 INCH BRULE SD PUBLIC
3 HOUR TOTAL FROM 9 AM TO 12 PM.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1216 PM CDT FRI AUG 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1200 PM HEAVY RAIN 3 S CHAMBERLAIN 43.77N 99.32W
08/02/2019 M3.05 INCH BRULE SD ASOS
CORRECTS PREVIOUS HEAVY RAIN REPORT FROM 3 S
CHAMBERLAIN. 3 HOUR TOTAL FROM 9 AM TO 12
PM.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1218 PM CDT FRI AUG 2 2019
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1200 PM HEAVY RAIN 2 NNW HURON 44.39N 98.23W
08/02/2019 M2.07 INCH BEADLE SD ASOS
2 HOUR STORM TOTAL, FROM 10 AM TO 12 PM.
&&
ATThe national radar mosaic for the moment the first event began.
5 flood. Local standard time, as filed.
Water up to a foot in depth ponded across sections of South Dakota Highway 37 south of Huron.
Water ponded to a few inches depth over U.S. Highway 14 on the east side of Huron.
Heavy rainfall of 3 to 5 inches produced flooding of fields and small creeks near Chamberlain. Several inches of flowing water was reported over roads.
Excessive rainfall caused erosion of a culvert under Truck Route 37 to the west of Huron.
Heavy rain resulted in street flooding to a depth of approximately 6 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2019Every state in 2019This day in weather historyWarnings in South Dakota, August 2019
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: 852036, 852041, 852053, 853944, 852058.