Strong frontal forcing resulted in the redevelopment of elevated thunderstorms during the very early morning to the west of the band from the previous evening. Storms quickly became linear with the development of a couple of mesovortices, which were the focus of damaging winds while tracking northeast along the line.
Every event with a place to put it. 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.
Strong frontal forcing resulted in the redevelopment of elevated thunderstorms during the very early morning to the west of the band from the previous evening. Storms quickly became linear with the development of a couple of mesovortices, which were the focus of damaging winds while tracking northeast along the line. Heavy training rainfall brought areas of flooding.
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 9, 3:50 AM CST, 43 minutes earlier.
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
450 AM CDT Tue Jun 9 2020
.SHORT TERM...(Today and Tonight)
Issued at 450 AM CDT Tue Jun 9 2020
More active weather in the short term, with concern continuing
around the short term precipitation concerns west of the James
River, the potential for marginally severe hail in the same area, a
few more severe storms in and around northwest Iowa midday through
mid-afternoon, and stronger synoptic winds later today and tonight.
Ongoing convection as expected has backed gradually westward from
the earlier corridor of severe storms from the mid evening to early
overnight hours, in response to strong frontogenetic forcing with
the jet entrance across central SD. This jet associated with the
northern portions of a full latitude trough through the Rockies/high
Plains, with a second upper wave moving toward the central/southern
Plains, which is then steering northward the remnant
circulation/moisture from Cristobal toward the mid/upper Mississippi
valley. CAMS doing a decent job with this initial precipitation
across NE/SD, and given the 40-50kt shear and elevated instability
on order of 1000 J/kg for the elevated parcels over the slowly
expanding cold pool (edge to MML/FSD/YKN by 09z) would not close
minds toward potential for a couple of marginally severe hailstones
early this morning. However, much more pressing will be the
potential rainfall over the next 1-3 hours, with now a tendency for
linearly oriented bands to start to shift slowly eastward with the
deeper convergence axis now into Brule/Gregory/western Charles Mix
county. This will work toward areas which received some heavier
rainfall earlier in the night, and will be monitoring for flash
flood potential early this morning. However, signals for
maintaining the convection start to weaken a bit and shift eastward
through mid-morning, so will allow the flood watch to expire at 7 am.
Gradual eastward shift of the frontal precip will work into areas
that have been precipitation free during the morning, but likely to
remain below severe thresholds moving through eastern SD.
Complexity of the larger scale flow will put northwest Iowa and
southwest MN into weaker flow regime between the various pieces
during the day, but will also be the location of the lower-level
convergence by midday and early afternoon. Shear is not terribly
strong for any afternoon development, so the severe threat will be
more based on the roughly 1000-1400 J/kg MLCAPE with a decent surface-
3km component in proximity to any vorticity source due to
convergence in the weak flow field. Some marginally large hail,
water loaded wind gusts to 65 mph, and not out of the question for a
brief tornado. Potentially interfering with this will be the
influence of the Cristobal moisture into areas toward Highway 71
during the later morning and afternoon, which could act to stabilize
that area a bit more.
The main precipitation will continue to be focused along the mid-
level frontal boundary, but in a weakening state during the
afternoon and evening hours and the entire trough system slips
eastward. Have maintained the highest PoPs in this zone, and with
lapse rates not as weakly unstable, would see mainly rain with a few
embedded storms. Precip rates, while not as high as those with
storms in current night, could bring a good quarter to half inch per
hour in a few spots. Precipitation should shift mainly east of I-29
after midnight, and be mostly ended as subsidence behind the main
upper trough settles in early Wednesday morning.
The other issue with the frontal band will be some intense
synoptic winds expected to develop. Some stronger winds already
taking shape west of the leading precipitation banding through
central SD/NE early this morning, and most models indicate
potential for winds to reach 30 to 45 kts in the mixed layer as
the system shifts eastward through tonight. Some of the higher
winds (50-60 kts) seem to be overdone by select hi-res solutions,
but certainly bears watching especially given the winds already
revealing themselves this morning. For now, have issued a wind
advisory through the mid and lower Missouri River valley for later
this afternoon into tonight where gradient is somewhat stronger,
but could see the need to expand through I-29 and eastward.
Concern keeping away from an earlier and further west/north
issuance are potential precipitation drag.
.LONG TERM...(Wednesday through Monday)
Issued at 450 AM CDT Tue Jun 9 2020
Quiet weather, other than being quite breezy on Wednesday, looks
to settle in for much of the remainder of the forecast. Deep
mixing northwest flow with temps mainly in the lower to mid 70s
appears reasonable, with only a small chance for some lingering
precip early in the day east of I-29. More generally westerly flow
into Thursday as well, with a shade warmer in the upper 70s to
around 80.
Amplifying upper level ridge to the west late in the week will help
push a weak boundary southward into the area by Friday. Not
impossible that could be in play for a high-based shower/storm as
warm advection again commences aloft, but not recognized at this
point by the blend. Depending on the frontal location, in play for
temps to end up a shade warmer on Friday as well. Ridge shifts
eastward through the weekend, with conditions becoming more windy.
Perhaps an isolated shower/storm late in the weekend, but nowhere
near a lock. Warmest day likely by Monday with front moving toward
the area, and well within the thermal ridge.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1257 AM CDT Tue Jun 9 2020
Widespread precipitation around the James River valley and
westward will be hard pressed to expand too much eastward
overnight. Expansion of the cold pool likely to keep more intense
convection as well as the main thunder threat along the eastern
tier of increasing stratiform area, meaning likely just some
infrequent thunder threat around KHON. Will be a while before
precipitation actually works into KFSD/KSUX areas, which will
likely come as the synoptic boundary shifts into Iowa by early
afternoon. Winds will increase behind the surface front, likely
gusting at times to 30-40 knots through the evening.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Flash Flood Watch until 7 AM CDT this morning for SDZ038-039-050-
052>054-057>060-063>065-068.
Wind Advisory from 4 PM this afternoon to 4 AM CDT Wednesday for
SDZ068>070.
Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
SDZ071.
MN...NONE.
IA...Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
IAZ020-031.
NE...Wind Advisory from 4 PM this afternoon to 4 AM CDT Wednesday for
NEZ013.
Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
NEZ014.
&&
SHORT TERM...Chapman
LONG TERM...Chapman
AVIATION...ChapmanPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1135 PM CDT MON JUN 8 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1028 PM HAIL DELMONT 43.27N 98.16W
06/08/2020 E0.70 INCH DOUGLAS SD TRAINED SPOTTER
MOSTLY PEA-SIZED HAIL, SOME DIMES.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1143 PM CDT MON JUN 8 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1134 PM TORNADO 8 E CARTHAGE 44.17N 97.56W
06/08/2020 MINER SD TRAINED SPOTTER
CONFIRMED TORNADO ON THE GROUND.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1208 AM CDT TUE JUN 9 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1104 PM HAIL FEDORA 44.01N 97.79W
06/08/2020 M1.00 INCH MINER SD TRAINED SPOTTER
TIME ESTIMATED FROM RADAR.
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1229 AM CDT TUE JUN 9 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1155 PM TSTM WND GST 5 SSE CANOVA 43.81N 97.48W
06/08/2020 M56 MPH MCCOOK SD PUBLIC
&&
ATPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1231 AM CDT TUE JUN 9 2020
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1155 PM TSTM WND GST 5 S CANOVA 43.81N 97.49W
06/08/2020 M56 MPH MCCOOK SD PUBLIC
TIME ESTIMATED FROM RADAR.
&&
ATThe Sioux Falls radar (KFSD), 141 km away, was scanning. The volume nearest the first event began at 10:33 UTC.
16 thunderstorm wind, 3 flash flood. Local standard time, as filed.
Damage was done to several trees, and the covering was ripped off a hoop barn. Property damage costs are rough estimates.
A concrete silo was toppled and a door to a metal shed bent inward. Property damage costs are rough estimates.
A farmstead suffered damage to several trees and two grain bins. A concrete silo was toppled. Property damage costs are rough estimates.
On a farmstead, a concrete silo was toppled, trees uprooted, and windows broken on the house. Property damage costs are rough estimates.
Extensive damage occurred to a grain bin, with minor damage done to the roof of a pole barn. Property damage costs are rough estimates.
A personal weather station measured a wind gust to 59 mph.
Cattle and calf shelters were damaged. Several calves were killed. Property damage costs are rough estimates.
A pole barn was significantly damaged. Property damage costs are rough estimates.
A barn was destroyed, along with damage to the roof and siding of a home. Property damage costs are rough estimates.
The main floor of a home was destroyed. A detached garage was also destroyed. Property damage costs are rough estimates.
Several power poles were downed or snapped by wind. Property damage costs are rough estimates.
Numerous trees were uprooted or snapped throughout Mt. Vernon. Property damage costs are rough estimates.
Portions of a hog barn roof were blown off. Property damage costs are rough estimates.
Numerous three inch limbs were taken down, along with a few power poles. Property damage costs are rough estimates.
Numerous trees were uprooted or snapped throughout Mitchell. Property damage costs are rough estimates.
Several large branches were removed from trees, and a pickup topper was blown down the street. Property damage costs are rough estimates.
Several county roads were flooded. Rainfall overnight and through the morning totalled 3.94 inches at Corsica and 3.33 inches 10 miles west of Dimock. Property damage costs are rough estimates.
County roads were flooded from rainfall averaging from 3 to 4 inches across the area. 3.94 inches of rainfall occurred during the overnight and morning hours at Corsica, with 3.33 inches 10 miles west of Dimock. Property damage costs are rough estimates.
Several county roads were flooded from rainfall which averaged 3 to 4 inches around the area during the overnight and morning hours. Up to 3.95 inches rainfall occurred near Pickstown. Property damage costs are rough estimates.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2020Every state in 2020This day in weather historyWarnings in South Dakota, June 2020
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 2026-09-30. Each event’s entry at NCEI: 905358, 905363, 905372, 905380, 905387, 905495, 905425, 905438, 905442, 905454, 905465, 905469, 905477, 905486, 905491, 905493, 905526, 905541, 905549.