Thunderstorms erupted late evening on June 16 along a slightly elevated boundary with 2500-3500 J/kg MUCAPE and 30-35 knots of deep-layer effective shear. Initial storms quickly became widespread along the boundary from south central to east central South Dakota and evolved into a large bow echo, which moved through southwest Minnesota and northwest Iowa with numerous reports of damaging winds…
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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.
Thunderstorms erupted late evening on June 16 along a slightly elevated boundary with 2500-3500 J/kg MUCAPE and 30-35 knots of deep-layer effective shear. Initial storms quickly became widespread along the boundary from south central to east central South Dakota and evolved into a large bow echo, which moved through southwest Minnesota and northwest Iowa with numerous reports of damaging winds mainly along and south of Interstate 90.
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 Jun 17, 1:06 AM CST, 19 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Sioux Falls SD 206 AM CDT Mon Jun 17 2024 .KEY MESSAGES... - Heavy rain continues to move through the Tri-State area this morning, with fairly widespread 1-3" totals expected and locally higher amounts. - Severe weather risk has diminished somewhat, with a more narrowed focus for large hail and some gusty winds along the Missouri River and then portions of northwest Iowa and southern Minnesota. - Continued uncertainty for severe weather risks for Monday, given cloud cover, lingering showers, and warming low-lvl temperatures. Lingering elevated hail risks may continue through the morning hours, with some renewed potential later this afternoon. - A progressive front moves through on Tuesday, bringing yet another risk for strong storms and locally heavy rainfall. - An unsettled week is ahead, with numerous thunderstorm risks into next weekend. The risk for locally heavy rainfall will be possible each day, with slightly more muted severe weather risks with lower shear. && .DISCUSSION... Issued at 204 AM CDT Mon Jun 17 2024 TONIGHT: Convection continues to track east across the Tri-State area. Generally the severe weather risks have lessoned as the strong mass convergence really gave no opportunity for storms to stay very discrete. Most guidance has also been focused far too north through the night, with the true effective low-lvl front focused south of I-90. Perhaps some residual severe weather risks will be possible along the Missouri River and then into portions of NW Iowa into Southern Minnesota, where instability is a bit higher, DCAPE remains nearly 1000 J/KG, and effective shear is AOA 40 KTs. However the greatest risk tonight will remain in the form of heavy rainfall. At this point, see no reason why convection will jog northward as some of the high resolution guidance suggests. Also, stronger shortwave energy continues to approach north central Nebraska, which will travel along the elevated boundary and continue the focus for heavy rain along and just north of the Missouri River and then further east into northern Iowa through 12Z. TODAY: We'll need to wait for the Nebraska shortwave to slide east before some weakening of deeper lift takes place. This may not happen until nearly mid-morning. However, with broad southwest flow and continued overrunning of the elevated boundary, persistent shower and thunderstorm development may continue north of the surface front through at least early to mid afternoon. Speaking of that surface front, it's current location south of the CWA may remain stationary until afternoon when some gradual retreat will begin in the afternoon. Convection risks later this afternoon and evening remain extremely conditional, partially due to continued capping over the CWA through the day, and the absence of deep synoptic lift. For now, will keep PoPs lower into the late afternoon hours, and temperatures cooler through the day due to cloud cover. TONIGHT: With the increase of the LLJ early in the evening, this could pose a risk for convection to develop along and north of the retreating warm front over northeastern SD. An additional focus point would be along a north to south oriented cold front in central South Dakota. However, unless a subtle wave sneaks through the Plains (ala the ECMWF) the best synoptic forcing is likely to take shape northwest of the CWA, so will only maintain a low chance PoP. The return of southerly surface flow behind the retreating warm front is likely to keep overnight low temperatures very warm and humid through the region. TUESDAY AFTERNOON-WEDNESDAY NIGHT: Uncertainty on where the surface cold front ends up Tuesday afternoon, but most guidance keeps this in our area (along/east of I-29) with the main surface low off to the north. Plenty of convergence along the front with lift by the evening hours as mid level wave and upper jet begin to track over the eastern half of the forecast area. Lots of warm and moist air ahead of the surface front; however, soundings show a fairly capped environment so afternoon/evening convection may be more elevated and tied to either the 850 mb or 700 mb front. Regardless, storms during Tuesday afternoon through night could be strong to severe. Main threats would be large hail and heavy rainfall. Can't rule out strong wind gusts, but this looks to be a secondary threat especially if storms are elevated. Prevailing storm motion is essentially parallel to the front so training storms could be a concern if the front is more slow moving. PWATs approach 2" which with days of rainfall, additional heavy rain could quickly pose issues with flooding. Stay weather aware. Showers and storms linger through Wednesday night as a couple of weak waves pass across the southwesterly flow regime and are supported by the right entrance of the upper jet. Some uncertainty with the subtle waves moving through the overall flow pattern. Not much in the way of instability during this time, so severe weather Wednesday into Wednesday night currently looks unlikely. Cooler temperatures look to prevail. THURSDAY ONWARD: Unsettled continues to be the theme of the forecast into next weekend with the blocking high remaining in place over the Mid Atlantic to TN Valley. Numerous waves/troughs swing through the mid level pattern, with the upper jet either overhead or just north. Models vary in the timing/location of each wave, but generally expect shower/storm chances to continue. Temperatures near normal.&& .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1127 PM CDT Sun Jun 16 2024 Storms have developed as of 17.04z from just north of KFSD stretching southwest into northwestern NE. Expect storms to continue developing and slowly moving northeast through the overnight hours. Large hail and heavy rainfall are possible. Expect MVFR and lower conditions with any storms. MVFR to possibly IFR stratus expected tomorrow with additional rounds of showers and storms through the period. Lower confidence in convective timing after daybreak Monday. Winds shift to more southerly through the period with gusts up to 30 knots. Could see some low level winds shear area wide after sunset Monday (18.01-02z) but given the expected gusts have omitted for now. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && DISCUSSION...Dux/SG AVIATION...SG
Hazardous Weather Outlook National Weather Service Sioux Falls SD 358 AM CDT Sun Jun 16 2024 IAZ020>022-031-032-NEZ013-014-SDZ071-171000- Plymouth-Cherokee-Buena Vista-Woodbury-Ida-Dixon-Dakota-Union- 358 AM CDT Sun Jun 16 2024 This Hazardous Weather Outlook is for portions of northwest Iowa, west central Iowa, northeast Nebraska, and southeast South Dakota. .DAY ONE...Today and Tonight A front focused along Highway 20 may be a focus point for isolated to scattered thunderstorms late Sunday afternoon and evening. If storms can develop, they will pose a risk of golf ball size hail and 60 mph winds. Additional thunderstorms are expected to develop after dark and into Monday morning, though some uncertainty remains on the exact location of development. Any storm overnight will be capable of producing 2 inch diameter hail and very heavy rainfall. .DAYS TWO THROUGH SEVEN...Monday through Friday. Isolated thunderstorms may be possible late Monday afternoon, and a strong storm could be possible before activity moves northward overnight. A very active weather pattern is likely through the next week, with several chances for thunderstorms capable of marginal severe weather and locally heavy rainfall. One slightly higher risk for severe storms may develop Tuesday afternoon and evening. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed this evening through early Monday morning. IAZ001>003-012>014-MNZ071-072-080-081-089-090-097-098-SDZ038>040- 050-052>070-171000- Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Lincoln-Murray- Cottonwood-Nobles-Jackson-Pipestone-Rock-Beadle-Kingsbury- Brookings-Gregory-Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora- Davison-Hanson-McCook-Minnehaha-Charles Mix-Douglas-Hutchinson- Turner-Bon Homme-Yankton- 358 AM CDT Sun Jun 16 2024 This Hazardous Weather Outlook is for portions of northwest Iowa, southwest Minnesota, central South Dakota, east central South Dakota, south central South Dakota, and southeast South Dakota. .DAY ONE...Today and Tonight Thunderstorms are expected late Sunday evening into Monday morning. Scattered strong to severe storms are possible, with the greatest risks of large hail up to and greater than 2 inches in diameter and 60 mph winds. Additionally, slow moving storms could produce locally heavy rainfall of 2 to 4 inches which could lead to flooding or brief flash flooding. There remains some uncertainty on where storms may develop. .DAYS TWO THROUGH SEVEN...Monday through Friday. Thunderstorms are expected to continue through at least early Monday afternoon. While some storms could still produce hail up to golf ball size, the greatest risk will come from locally heavy rain and potential flooding. Additional thunderstorms may begin to develop late Monday afternoon and Monday evening, with the greatest focus for storms west of the James River. Golf ball size hail and 60 mph winds may be possible in this activity. A very active weather pattern is likely through the next week, with several chances for thunderstorms capable of marginal severe weather and locally heavy rainfall. One slightly higher risk for severe storms may develop Tuesday afternoon and evening along and east of Interstate 29. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed late Sunday evening through mid- morning Monday.
The Sioux Falls radar (KFSD), 84 km away, was scanning. The volume nearest the first event began at 07:24 UTC.
6 thunderstorm wind. Local standard time, as filed.
Thunderstorm wind gusts up to 59 mph were measured by the Iowa Road Weather Information System site RSYI4 near Sibley.
Thunderstorm wind gusts up to 60 mph were measured by the Iowa Road Weather Information System site RTNI4 near Orange City.
Thunderstorm wind gusts to 59 mph were measured by a personal weather station in Lake Park.
Two cars were damaged at one residence and at least two other homes have trees and branches down on the buildings with minor damage due to thunderstorm wind gusts.
Thunderstorm wind gusts uprooted a 4 foot diameter cottonwood tree.
Thunderstorm wind gusts up to 60 mph were measured by a personal weather station near Orleans.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2024Every state in 2024This day in weather historyWarnings in Iowa, June 2024
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: 1195838, 1195839, 1195843, 1195841, 1195842, 1195840.