An isolated storm along a frontal boundary produced a local burst of damaging wind.
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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.
An isolated storm along a frontal boundary produced a local burst of damaging wind.
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 21, 5:30 PM CST, 36 minutes earlier.
AREA FORECAST DISCUSSION National Weather Service Sioux Falls SD 630 PM CDT Fri Jul 21 2023 .SHORT TERM...(This Evening through Saturday Night) Issued at 241 PM CDT Fri Jul 21 2023 Key Messages: 1. Chances for showers and storms continue for the rest of today and tomorrow. 2. A low end chance for severe storms is on the table tomorrow with large hail up to 1 inch in diameter and damaging gusts up to 60 mph possible. 2. Temperatures continue to warm with highs into the 90s likely by early next week. Dry conditions are likely with the incoming hot temperatures. --------------------------------------------------------------------- Another fairly nice afternoon is on tap for today as temperatures have warmed to the 70s and 80s while dew points have remained in the 50s to low 60s. Isolated showers have developed mainly along and east of a De Smet, South Dakota to Dell Rapids, South Dakota, to Spencer Iowa line. Should see these showers translate southeastwards through the rest of the afternoon hours. In terms of environment, low amounts of CAPE, < 1000 J/kg, are present along with only modest deep layer shear up to around 30 knots. Soundings reveal that the bulk of the instability is residing between 750 - 600 mb. This is also "splitting" the freezing level. With instability split around the freezing level, think that it will be hard to achieve adequate charge separation and thus result in limited lightning with any shower or storm. However, the same soundings also show an inverted-v signature below 750 mb which will allow for some gusty winds to mix to the surface. These gusts are expected to be below severe limits, maxing out around 30-40 mph. Any chance for rain will come to an end this evening as the boundary layer stabilizes. Low temperatures will fall to the 60s overnight. Saturday will be quite similar to Friday but highs will warm a touch more in response to slightly warmer 850 mb temperatures. Highs look to span from the low to mid 80s east of I-29 to the mid 80s to low 90s west of the interstate. The warmest temperatures will reside along the Missouri River, especially towards central South Dakota. Another shortwave trough will be traveling down the northwest flow, again remaining mainly in Minnesota. This wave looks to encounter a slightly better environment as instability will be bit higher with CAPE values up to 1000 - 1500 J/kg and effective shear between 30-40 knots. Soundings also show tall, skinny CAPE profiles since mid level lapse rates are less than 7 C/km. Dry air will again reside beneath 750 mb but inverted-v profiles will be larger than they were on Friday, indicating of DCAPE values up to either side of 1000 J/kg. Looking towards the top of the troposphere, upper level winds will be a bit stronger which is indicative of stronger shear aloft. This is just enough to introduce a low end hail risk tomorrow with the largest hail stones maxing out at the size of a quarter or 1 inch in diameter. Damaging winds are also possible given the low level dry air in place, with the strongest gusts reaching up to 60 mph. Any chance for storms will come to an end as diurnal mixing ceases in the evening. Low temperatures will again fall to the upper 50 to low 60s. .LONG TERM...(Sunday through Friday) Issued at 241 PM CDT Fri Jul 21 2023 Temperatures begin to warm on Sunday as 850 mb temperatures warm to the upper teens to mid 20s. Mixing this to the surface will result in high temperatures in the 80s east of the James River and 90s west of the James. Medium range guidance does hint at more shortwave troughs passing through the area. However, a cap will be in place due to the previously mentioned warm 850 mb temperatures. This cap looks to prevent any chance for convective initiation from being reached and thus keeping conditions on the quiet side. Overnight low temperatures will also be warmer as temperatures only fall to the 60s. Attention turns to the building upper ridge over the southwestern CONUS Monday through Friday next week. 850 mb temperatures will continue to warm up to well into the 20s, resulting in hot high temperatures into the upper 80s to upper 90s. Ensembles remain in agreement in temperatures as they all show a near 100% chance for temperatures to exceed 90 degrees. Temperatures may also reach 100 degrees but confidence is not as high in this possibility. The GFS and Euro ensembles show a 30-60% chance for exceeding 100 degree temperatures but the Canadian ensemble shows a zero percent chance for breaking into the triple digits. Think this may be because of the models cold bias. Questions remain in terms of precipitation. Medium range guidance does show the better jet energy getting pushed into Canada. Weaker shortwaves are shown rounding the top of the ridge but capping due to the strong thermal ridge may prevent convection from developing. BUFKIT soundings do show the possibility of fully mixing out and eroding the cap. However, fully mixing out will mix dry air to the surface and diminish instability. Ensembles agree with the lack of precipitation as they all show only a 10-30% chance for exceeding a tenth of an inch of rain. All this to say that next week looks to be a hot and dry week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 620 PM CDT Fri Jul 21 2023 Scattered showers/storms continue through sunset, generally along/east of I-29. Could see some small hail and gusts to 35 knots with the stronger storms. Cloud bases and visibility have generally stayed above VFR criteria, but have seen some isolated MVFR conditions in heavier rain. Did not include TSRA mention at KSUX for now as confidence is low in storms holding together as they head southeast, and should remain outside the vicinity. Winds have become light and variable due to the numerous outflow boundaries and weakening of daytime mixing. Winds tonight remain light and variable, and can't rule out some patchy fog development for those which received rainfall this evening and in river valleys. Winds increase and turn northwesterly into Saturday early afternoon. Diurnal cumulus redevelop tomorrow, with additional isolated to scattered showers/storms mainly along/east of I-29. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && SHORT TERM...Meyers LONG TERM...Meyers AVIATION...SG
Hazardous Weather Outlook National Weather Service Sioux Falls SD 429 AM CDT Fri Jul 21 2023 IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097- 098-NEZ013-014-SDZ038>040-050-052>071-220930- 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- 429 AM CDT Fri Jul 21 2023 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. Isolated to scattered thunderstorms will be possible this afternoon and early evening. Severe weather is not expected, though storms may produce locally gusty winds. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Isolated to scattered thunderstorms are possible again Saturday afternoon and evening. While the risk of severe weather is low, isolated stronger storms could produce strong wind gusts and small hail. Increasing heat will build east across the region Sunday through much of next week. By Tuesday and Wednesday, widespread highs in the 90s are likely, with heat indices possibly topping 100 degrees. Prepare now to ensure you are ready for the combination of dangerous heat and humidity. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
Preliminary Local Storm Report
National Weather Service Sioux Falls SD
633 PM CDT Fri Jul 21 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0622 PM Hail 4 SW Ward 44.11N 96.51W
07/21/2023 M0.88 inch Moody SD Trained Spotter
&&
JCThe Sioux Falls radar (KFSD), 112 km away, was scanning. The volume nearest the first event began at 00:06 UTC.
1 thunderstorm wind. Local standard time, as filed.
Several 3 to 4 inch diameter tree limbs were downed by thunderstorm winds.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2023Every state in 2023This day in weather historyWarnings in Iowa, July 2023
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: 1123963.