Overall, precipitation near to a little above normal across northwest portions of Iowa led to the alleviation of severe drought for some areas.
Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
Overall, precipitation near to a little above normal across northwest portions of Iowa led to the alleviation of severe drought for some areas.
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 31, 9:25 PM CST, 2 hours 35 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 1025 PM CDT Tue Aug 31 2021 .SHORT TERM...(This Evening through Wednesday) Issued at 409 PM CDT Tue Aug 31 2021 The next 24 hours appears to be very quiet across the area as sharp ridging aloft builds through the northern Plains. With east to southeast flow today, have seen development of a flat diurnal cumulus field, and conditions have resulted in a slightly better mixing depth and drying out of dew point readings into the very comfortable lower to mid 50s most areas north of I-90. As a result, when winds diminish and cumulus dissipate this evening, temps should fall fairly efficiently, with lows likely in the mid 50s to lower 60s. On Wednesday, temps will likely be just a smidge warmer than today with increased southeasterly gradient resulting in gusts to 20-30 mph. About the worst part of a day which will feature an increase in higher level clouds through the afternoon with temps in the upper 70s to mid 80s. .LONG TERM...(Wednesday Night through Tuesday) Issued at 409 PM CDT Tue Aug 31 2021 Trough across the western U.S. ejects first piece of energy into the upper ridge which glances across the high plains later Wednesday into Wednesday night. This should start to push the low- level frontal zone into the western portions of the state, with development focused on this boundary in upslope flow. For this reason, will likely be a slower eastward progression with the high meridional component, with most of the threat likely holding off until after midnight, when the second piece of energy aloft coming out of the southwestern U.S. emerges into the western Plains. This wave comes along with a surge of monsoonal moisture, and a fairly deep moist layer aloft. Warm advection aloft will push out gradually through eastern SD later in the night with convergence in the lower levels drifting into central SD. Will likely get an elevated offshoot of convection swinging east/northeast across eastern SD late night. With mid-level lapse rates in pre-precip environment at 7.5-8.5C/km, is enough elevated instability that some severe weather a concern late night mainly as far east as south central SD to the mid-James River valley around KHON, but far more likely to have some locally heavy rainfall through Wednesday night, with effective shear not too impressive above 2km. Thursday will bring the best precipitation chances to most areas, but by no means should be an all-day affair. Other than the chance for a elevated flier scooting out ahead of the boundary with the early day warm advection, the strong dynamic push aloft and interaction with the low-level front should produce a broad swath of showers and embedded thunder across the area, pressing slowly toward the east. Instability suggested to be fairly meager (toward moist neutral profiles), and with the fairly warm cloud layer and persistence of meridional flow ahead of the front, should be more likely to find some areas of heavy rainfall (averaging 1-2", locally higher) with a somewhat smaller severe weather threat. 0-1 km shear does focus near the front, so would not be shocked to end up with the low-LCLs to find a rogue tornado or funnel, especially if the potential frontal wave develops as per most model solutions. Rainfall works eastward, and should be mostly out of the area by daybreak Friday, with the notable exception being more shallow light precipitation in advance of the inverted trough likely somewhere near northwest Iowa/southwest Minnesota per mean solutions. This should be mainly a morning phenomena, but not sure that rapidly weakening low-level flow behind wave/front will be enough to fully flush out the lower clouds. As stands, temps in the initial blend were roughly at the 25th percentile, and that seems to be an acceptable place to be given the potential for clouds and weakening flow. A quick moving wave looks to approach/pass north of the area later Friday night into early Saturday, and will bring a small chance of showers/isolated thunder, of which coverage should diminish heading east toward/past I-29. Transition to a northwest flow looks to keep the bulk of the weekend dry and seasonably cool for the unofficial end to summer with highs in the 70s and lows in the 50s. More uncertainty if waves in northwest flow could bring a small precip chance around Monday/Monday night with very little agreement in timing/track/strength. A bit earlier than the forecast blend is certainly in the more likely timing distribution, so will have to watch to see if Labor Day gets a blemish past the current small chance by evening. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1021 PM CDT Tue Aug 31 2021 Still at least some hints we could see some patchy fog in low lying areas across NW IA and far SE SD later tonight but have kept restrictions out of KSUX given low confidence. Otherwise, look for southeasterly winds gusting between 20-25 kts Wednesday afternoon with some upper level wildfire smoke returning. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && SHORT TERM...Chapman LONG TERM...Chapman AVIATION...Kalin
Hazardous Weather Outlook National Weather Service Sioux Falls SD 516 AM CDT Tue Aug 31 2021 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-011030- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee- Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson- Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory- Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook- Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton- Union- 516 AM CDT Tue Aug 31 2021 This Hazardous Weather Outlook is for northwest Iowa, west central Iowa, southwest Minnesota, northeast Nebraska, central South Dakota, east central South Dakota, south central South Dakota and southeast South Dakota. .DAY ONE...Today and tonight. No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. 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
831 PM CDT TUE AUG 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0527 PM HAIL 5 SW FREEMAN 43.30N 97.49W
08/30/2021 E1.75 INCH HUTCHINSON SD PUBLIC
LIGHT RAIN AND MOSTLY SMALL HAIL, BUT A FEW
STONES AS BIG AS GOLF BALLS.
&&
TRMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
858 PM CDT TUE AUG 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1208 AM HAIL 2 SSE STICKNEY 43.56N 98.42W
08/31/2021 E1.00 INCH AURORA SD TRAINED SPOTTER
HEAVY RAIN AND HAIL UP TO THE SIZE OF
QUARTERS.
&&
TRMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
942 PM CDT TUE AUG 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1228 PM HAIL 6 E PARKSTON 43.40N 97.87W
08/30/2021 E0.88 INCH HUTCHINSON SD PUBLIC
HEAVY RAIN AND HAIL UP TO THE SIZE OF
NICKELS.
&&
TRMPRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1009 PM CDT TUE AUG 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1228 PM HAIL 6 E PARKSTON 43.40N 97.87W
08/30/2021 E0.88 INCH HUTCHINSON SD PUBLIC
HEAVY RAIN AND HAIL UP TO THE SIZE OF
NICKELS.
0441 PM HAIL 8 NW ETHAN 43.62N 98.11W
08/30/2021 E1.00 INCH DAVISON SD TRAINED SPOTTER
QUARTER SIZED HAIL AND HEAVY RAIN.
0503 PM HAIL 3 NNW ETHAN 43.58N 98.01W
08/30/2021 E1.00 INCH DAVISON SD TRAINED SPOTTER
LOTS OF VARIABLE SIZED HAIL AND HEAVY RAIN,
WITH BIGGEST STONES AS BIG AS QUARTERS.
0513 PM HAIL 1 NE ETHAN 43.55N 97.97W
08/30/2021 E0.88 INCH DAVISON SD TRAINED SPOTTER
HEAVY RAIN AND HAIL UP TO THE SIZE OF
NICKELS.
0518 PM HAIL 6 N MENNO 43.33N 97.58W
08/30/2021 E1.25 INCH HUTCHINSON SD PUBLIC
PICTURE VIA SOCIAL MEDIA. TIME ESTIMATED VIA
RADAR, LOCATION ESTIMATED VIA GENERAL
LOCATION ON SOCIAL MEDIA.
0527 PM HAIL 5 SW FREEMAN 43.30N 97.49W
08/30/2021 E1.75 INCH HUTCHINSON SD PUBLIC
LIGHT RAIN AND MOSTLY SMALL HAIL, BUT A FEW
STONES AS BIG AS GOLF BALLS.
0529 PM HAIL 6 S ALEXANDRIA 43.57N 97.79W
08/30/2021 E0.88 INCH HANSON SD PUBLIC
REPORT FROM SOCIAL MEDIA.
0538 PM HAIL 2 W CLAYTON 43.44N 97.69W
08/30/2021 E1.25 INCH HUTCHINSON SD TRAINED SPOTTER
HAIL UP TO THE SIZE OF HALF DOLLARS, AND
VERY LITTLE RAINFALL.
0548 PM HAIL 1 S CLAYTON 43.44N 97.66W
08/30/2021 M1.00 INCH HUTCHINSON SD PUBLIC
0706 PM HAIL HAWARDEN 43.00N 96.49W
08/30/2021 E1.00 INCH SIOUX IA PUBLIC
PICTURE VIA SOCIAL MEDIA.
0732 PM HAIL 6 S BERESFORD 42.99N 96.77W
08/30/2021 E1.75 INCH UNION SD PUBLIC
0738 PM HAIL 7 SW ALCESTER 42.94N 96.71W
08/30/2021 E0.75 INCH UNION SD PUBLIC
0758 PM HAIL 6 S BRIDGEWATER 43.46N 97.51W
08/30/2021 E1.00 INCH HUTCHINSON SD PUBLIC
CORRECTS PREVIOUS HAIL REPORT FROM 6 S
BRIDGEWATER. MOSTLY PEA SIZED HAIL, BUT A
FEW QUARTER SIZED STONES, AND HEAVY RAIN.
0930 PM HAIL 3 SSW FREEMAN 43.31N 97.46W
08/30/2021 E0.88 INCH HUTCHINSON SD PUBLIC
0936 PM HAIL 2 SW FREEMAN 43.33N 97.45W
08/30/2021 E0.75 INCH HUTCHINSON SD PUBLIC
CORRECTS PREVIOUS HAIL REPORT FROM 1 NW
FREEMAN.
0954 PM HAIL 2 SE IDA GROVE 42.32N 95.44W
08/30/2021 E0.75 INCH IDA IA TRAINED SPOTTER
HEAVY RAIN AND MOSTLY PEA SIZED HAIL, BUT A
FEW STONES AS BIG AS PENNIES.
1002 PM HAIL 6 S ARTHUR 42.25N 95.35W
08/30/2021 E1.75 INCH IDA IA TRAINED SPOTTER
GOLF BALL SIZED HAIL SHREDDED AND POUNDED
CROPS IN THE FIELD.
1208 AM HAIL 2 SSE STICKNEY 43.56N 98.42W
08/31/2021 E1.00 INCH AURORA SD TRAINED SPOTTER
HEAVY RAIN AND HAIL UP TO THE SIZE OF
QUARTERS.
0141 AM TSTM WND GST 2 WSW PICKSTOWN 43.05N 98.57W
08/31/2021 M55 MPH GREGORY SD MESONET
MESONET STATION 244 SD RWIS FT. RANDALL DAM.
0158 AM TSTM WND GST 1 E WAGNER 43.08N 98.28W
08/31/2021 M50 MPH CHARLES MIX SD MESONET
PERSONAL WEATHER STATION RECORDED WIND GUST
OF 50 MPH.
&&PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1038 PM CDT TUE AUG 31 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1006 PM HAIL 8 S ARTHUR 42.23N 95.34W
08/30/2021 E1.75 INCH IDA IA TRAINED SPOTTER
CROPS BADLY DAMAGED BY HAIL ESTIMATED AS
LARGE AS GOLF BALLS.
&&
TRMThe national radar mosaic for the moment the first event began.
7 drought. Local standard time, as filed.
Temperatures at Sioux Rapids and Storm Lake were 2 to 3 degrees above normal during September, with precipitation from 75-100 percent of normal, which led to a continuation of severe (D2) drought conditions.
Temperatures during September averaged around 2 degrees above normal at Cherokee, while precipitation remained 75-100 percent of normal, which led to a continuation of severe (D2) drought conditions. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
Temperatures at Spencer were 2 to 3 degrees above normal during September, with precipitation below normal until heavy rainfall occurred on the final day of the month to push amounts to 100-125 percent of normal. Severe (D2) drought conditions continued through the month.
Nearly two inches of rainfall at the beginning of September at Spirit Lake and Lake Park led to an improvement in drought conditions from severe (D2) to moderate (D1) at the start of the month. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
Temperatures during September averaged 3 to 4 degrees above normal at Primghar and Sanborn, while precipitation remained around 75 percent of normal, which led to continuation of severe (D2) drought conditions. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
Rainfall of a half inch to inch at the beginning of September at Le Mars and Remsen led to an improvement in drought conditions from severe (D2) to moderate (D1) by mid-month. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
Rainfall around an inch at the beginning of September at Sioux City and 4 miles north northeast of Hornick led to an improvement in drought conditions from severe (D2) to moderate (D1) by mid-month. Crop damage is an estimate from insured losses. Information provided by the United States Department of Agriculture.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2021Every state in 2021This day in weather historyWarnings in Iowa, September 2021
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: 985464, 985465, 985466, 985467, 985468, 985469, 985470.