Iowa, 2021

Tornadoes and Damaging Winds in Iowa, December 15 to 16, 2021

December 15 to 16, 2021 · NWS FSD · 69 events in 11 counties and zones

An unprecedented storm system lifted across the central Plains from December 15 into the early hours of December 16. Kinematic fields were at the top of the climatological distributions, leading to extreme wind shear in the lowest levels.

Where it happened

Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
0
Injuries
0
Property damage
$4.0 million
Crop damage
None recorded
Events
69

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.

What happened

The episode as NWS FSD wrote it up.

An unprecedented storm system lifted across the central Plains from December 15 into the early hours of December 16. Kinematic fields were at the top of the climatological distributions, leading to extreme wind shear in the lowest levels. Ahead of the system, record high temperatures with surface dew point values into the 50s and lower 60s surged toward northwest Iowa and resulted in instability not typically found in December.

A serial derecho developed across Nebraska and Kansas during the early afternoon and raced to the northeast toward Iowa and Minnesota, with widespread damaging wind and a few tornadoes. The first Storm Prediction Center moderate risk, as well as severe thunderstorm and tornado warnings during December, were issued for the Sioux Falls warning area. There was even remaining snow cover in parts of northwest Iowa north of Highway 18 and into southwest Minnesota as the severe storms evolved during the afternoon and evening hours.

As the cold front swung through the area behind the convective line, 60 to 75 mph winds aloft were mixed to the surface and resulted in a few synoptic wind gusts up to hurricane force. Some light wintry precipitation also fell during the transition toward the much colder air, which led to flash freezing as temperatures fell as much as 40 degrees during the overnight hours.

What forecasters said that day

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 Dec 15, 2:50 PM CST, 1 hour 25 minutes earlier.

Area forecast discussion, Dec 15, 2:50 PM CST, 1 hour 25 minutes before
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
250 PM CST Wed Dec 15 2021

.SHORT TERM...(This Evening through early Thursday Morning)
Issued at 248 PM CST Wed Dec 15 2021

A SIGNIFICANT AND RARE EVENT FOR MID DECEMBER REMAINS ON TRACK

Let's jump right into it shall we? Early afternoon satellite imagery
showing an ACCAS field moving northeastwards into the area, and is a
great indicator of the mid-level instability that we currently have
in place across the region. Also on satellite, the leading edge of
the surface low can clearly be seen as it is lighting up a line of
showers and thunderstorms across south-central Nebraska as of ~1:15
PM. Expect this line to reach the Sioux City area right around 4 PM,
which will continue tracking northeastwards towards south central
Minnesota by around 6 PM.

With around 1000 J/kg of CAPE to work with, 50-80 knots of shear,
and 200-300 (m^2 s^-2) of ESRH, a line of thunderstorms currently
over central Nebraska are expected with embedded tornadoes possible.
Have collaborated and issued a tornado watch, and includes areas
along a line from Ponca, NE & Sioux City, IA out towards Jackson, MN
and Spencer, IA. While tornadoes are possible, the more confident
threat is for strong damaging winds as strong as 70 to 80 mph.
Severe Thunderstorm Warnings and Tornado Warning have already been
issued across central Nebraska, so please take these storms and
their warnings seriously.

For areas west of the main line of storms, showers and thunderstorms
are possible for the remaining afternoon hours before the inverted
trough reaches the area bringing cooler air along with it. This will
bring a changeover from rain to a wintry mix, where an hour or two
of rain/freezing rain/snow will be possible, before the switch all
to snow takes place as we head into the evening hours. The other
thing to watch this afternoon is the strong synoptically driven wind
gusts, which will begin to impact areas along the MO River Valley by
later this afternoon.

For the evening hours, the non-convective related winds will
continue to strengthen as the surface low and mid-level low move
across the area, with the southern periphery mixing down 60 to 80
knot winds. This will result in fairly widespread 60 to 70 mph wind
gusts down at the surface, with advisory level winds lingering
around past midnight. Might need to issue a wind advisory after the
high wind warning expires at 3 AM, but will hold off for now to
avoid confusion.

Winter weather wise, the transition to snow will continue to take
place during the evening hours, though no ice accumulations are
expected. Snowfall amounts have been increased slightly on the
backside of the low as some frontogenesis will likely lead to some
banding to take place, but again as this system is moving so quickly
snowfall accumulations will overall remain light, though a couple
locations could pick up a quick 1 to 2 inches. Due to the falling
snow and HREF probabilities showing a quick moving area of around 1
inch per hour snowfall rates very likely leading to reduced
visibilities, have expanded the Winter Weather Advisory to increase
awareness of this threat. The other threat tonight will be a flash
freeze event with all of this snowmelt and rainfall, so be vigilant
if you're traveling tonight.

.LONG TERM...(Thursday Morning through Wednesday)
Issued at 248 PM CST Wed Dec 15 2021

Thursday will likely remain a little breezy with seasonal
temperatures, with our next chance for light snow occurring on
Friday for areas along and north of the Highway 14 corridor. With
severe convection knocking on our southern counties, long term
discussion is ended early to focus on the current threats.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1132 AM CST Wed Dec 15 2021

The calm before the storm will continue for the next couple hours,
but by the mid/late afternoon hours expect that to change. A line of
thunderstorms is expected to form in eastern Nebraska, and will
blossom northeastwards across portions of far eastern Nebraska,
SW South Dakota, but mostly across NW Iowa. Wind gusts under the
storms could approach 70+ mph. Otherwise, non-storm related winds
will crank up later this afternoon into the evening hours as rain
spreads out across the area, with period of 60-70 mph being
possible. Snow moves in from the west this afternoon, bringing the
transition from rain to snow northeastwards into the evening
hours.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Warning until midnight CST tonight for SDZ050-063>071.

     Winter Weather Advisory until 3 AM CST Thursday for SDZ038>040-
     050-052>060-063-064.

     High Wind Warning until 3 AM CST Thursday for SDZ038>040-052>062.

MN...Winter Weather Advisory until 3 AM CST Thursday for MNZ071-072.

     High Wind Warning until 3 AM CST Thursday for MNZ071-072-080-081-
     089-090-097-098.

IA...High Wind Warning until midnight CST tonight for IAZ001>003-
     012>014-020>022-031-032.

NE...High Wind Warning until midnight CST tonight for NEZ013-014.

&&

SHORT TERM...APT
LONG TERM...APT
AVIATION...APT
Hazardous weather outlook, Dec 15, 4:17 AM CST, 11 hours 58 minutes before
Hazardous Weather Outlook
National Weather Service Sioux Falls SD
417 AM CST Wed Dec 15 2021

MNZ071-SDZ038>040-050-052>066-068-069-161030-
Lincoln-Beadle-Kingsbury-Brookings-Gregory-Jerauld-Sanborn-Miner-
Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-Minnehaha-
Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-
417 AM CST Wed Dec 15 2021

This Hazardous Weather Outlook is for portions of southwest
Minnesota, central South Dakota, east central South Dakota, south
central South Dakota, and southeast South Dakota.

.DAY ONE...Today and Tonight

Dense fog in areas along and east of I-29 is expected to continue
through late morning. If traveling, be sure to slow down,
increase your following distance, and use your low beam
headlights.

Expect very strong winds to prevail this afternoon and evening,
with gusts as high as 60 to 70 mp at times. Wind direction will
initially be from the south-southwest, turning westerly late this
afternoon.

Otherwise, look for temperatures to quickly plummet below
freezing later this evening, resulting in a transition to snow.
Strong winds during this time will also continue to linger,
causing reduced visibilities to become common. While
central/south-central SD stands the best chance of seeing any
accumulations, could see snow fall as far east as I-29. Lastly,
may also see a flash freeze occur across portions of our area,
resulting in slippery travel conditions through the overnight
period.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

IAZ001>003-012>014-020>022-031-032-MNZ072-080-081-089-090-097-098-
NEZ013-014-SDZ067-070-071-161030-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Lincoln-Union-
417 AM CST Wed Dec 15 2021

This Hazardous Weather Outlook is for portions of northwest Iowa,
west central Iowa, southwest Minnesota, northeast Nebraska, and
southeast South Dakota.

.DAY ONE...Today and Tonight

Dense fog in areas along and east of I-29 is expected to continue
through late morning. If traveling, be sure to slow down,
increase your following distance, and use your low beam
headlights.

Expect very strong winds to prevail this afternoon and evening,
with gusts as high as 60 to 70 mp at times. Wind direction will
initially be from the south-southwest, turning westerly late this
afternoon. In addition to the overall windy conditions, there is
also a chance for strong to severe thunderstorms across portions
of NW Iowa and SW Minnesota during the late afternoon and early
evening. Damaging winds would be the primary hazard with storms,
but isolated tornadoes are also possible.

Otherwise, look for temperatures to quickly plummet below
freezing later this evening, resulting in a transition to snow.
May also see a flash freeze occur across portions of our area,
resulting in slippery travel conditions through the overnight
period.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

The radar

The Omaha radar (KOAX), 108 km away, was scanning. The volume nearest the first event began at 22:15 UTC.

Open the radar archive at this moment

Event by event

43 thunderstorm wind, 15 tornado, 11 high wind. Local standard time, as filed.

Tornado, Woodbury

When
December 15, 4:15 PM CST to 4:16 PM CST
Where
Woodbury County, 2.53 mi SSW of Salix to 1.8 mi SW of Salix
Rating
EFU
Path length
0.8 mi
Path width
20 yd
Reported by
Public
Coordinates
42.288, -96.304

A public video revealed that a tornado briefly spun up in an open field southwest of Salix between Benton Avenue and Interstate 29 north of 290th Street. The tornado traveled north northeast and lifted just south of 280th Street. The average path width was estimated at 20 yards.

Thunderstorm Wind, Woodbury

When
December 15, 4:19 PM CST to 4:20 PM CST
Where
Woodbury County, Hornick
Measured
65 kt (75 mph) estimated gust
Property damage
$25,000
Reported by
Emergency Manager
Coordinates
42.230, -96.100

Thunderstorm winds overturned several propane tanks. Property damage costs are a rough estimate.

Tornado, Woodbury

When
December 15, 4:20 PM CST to 4:24 PM CST
Where
Woodbury County, 3.37 mi NNW of Salix to 4.08 mi ENE of Sergeant Bluff
Rating
EF1
Path length
4.56 mi
Path width
75 yd
Property damage
$250,000
Reported by
NWS Storm Survey
Coordinates
42.366, -96.302

The tornado touched down near Buchanan Avenue between 230th and 240th streets and moved north northeast, impacting four farmsteads. One machine shed was completely destroyed with debris deposited about 1 mile downstream in an open field. Several other outbuildings were damaged along the track along with a few trees. The tornado lifted just east of the intersection of Old Highway 141 and County Home Road. The average path width was 50 yards and the maximum estimated wind speed was 105 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:21 PM CST
Where
Woodbury County, 5.28 mi WNW of Sioux City
Measured
61 kt (70 mph) estimated gust
Reported by
Public
Coordinates
42.520, -96.480

A large tree was uprooted by thunderstorm winds.

Thunderstorm Wind, Woodbury

When
December 15, 4:23 PM CST
Where
Woodbury County, 3.74 mi NW of Bronson
Measured
61 kt (70 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.455, -96.256

Roofing material on several hoop barns was damaged. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:23 PM CST to 4:24 PM CST
Where
Woodbury County, 0.86 mi SE of (Sux)sioux City Arpt
Measured
71 kt (82 mph) measured gust
Reported by
ASOS
Coordinates
42.390, -96.370

A thunderstorm wind gust of 82 mph was measured by Automated Surface Observing System KSUX.

Tornado, Woodbury

When
December 15, 4:25 PM CST to 4:32 PM CST
Where
Woodbury County, 1.11 mi NE of Bronson to 4.96 mi NNE of Lawton
Rating
EF2
Path length
8.44 mi
Path width
100 yd
Property damage
$500,000
Reported by
NWS Storm Survey
Coordinates
42.429, -96.182

The tornado spun up two miles northeast of Bronson along 190th Street, around one mile west of the intersection with Emmett Ave, where it ripped a portion of the roof off a single family home and damaged an outbuilding, with debris sent 100 yards to the north into a field. The tornado continued northeast across open fields until it hit two large metal utility transmission towers, and deposited the electric lines across U.S. Highway 20, resulting in the closure of U.S. Highway 20 east of Lawton for two days. The tornado crossed U.S. Highway 20 less than a mile east of Lawton, then made a more northward turn. As the tornado approached Fayette Avenue, it impacted multiple farmsteads with damage to a few barns and sheds, as well as broken and snapped tree limbs. A machine shed at one farmstead was completely destroyed along with a concrete silo and lean-to shed. Multiple power poles were snapped along 140th Street. Minor damage was also noted to shingles on a couple single family homes.|The tornado eventually lifted near the intersection of 110th Street and Fayette Avenue. The average path width was 75 yards and the maximum estimated wind speed was 130 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:25 PM CST to 4:26 PM CST
Where
Woodbury County, 2.95 mi SSE of Sioux City
Measured
65 kt (75 mph) estimated gust
Property damage
$10,000
Reported by
Public
Coordinates
42.460, -96.360

Several power poles were leaning after strong thunderstorm winds. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:28 PM CST to 4:29 PM CST
Where
Woodbury County, 0.99 mi NE of Lawton
Measured
70 kt (81 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.489, -96.165

Thunderstorm winds tossed an empty grain bin, and resulted in considerable tree damage. Minor roof damage was also done to the residence at this location. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:28 PM CST to 4:29 PM CST
Where
Woodbury County, 1.46 mi ENE of Lawton
Measured
69 kt (79 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.489, -96.154

Thunderstorm winds dented large grain bins on the southeast facing side, and numerous shingles were removed from the south side of a house. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:31 PM CST to 4:32 PM CST
Where
Woodbury County, 3.35 mi NE of Lawton
Measured
69 kt (79 mph) estimated gust
Property damage
$10,000
Reported by
NWS Storm Survey
Coordinates
42.519, -96.141

Thunderstorm winds removed numerous shingles from a house. Property damage costs are a rough estimate.

Thunderstorm Wind, Woodbury

When
December 15, 4:34 PM CST to 4:35 PM CST
Where
Woodbury County, 0.86 mi SW of Anthon
Measured
74 kt (85 mph) estimated gust
Property damage
$75,000
Reported by
Public
Coordinates
42.390, -95.880

Thunderstorm winds destroyed a garage and cattle barn. Property damage costs are a rough estimate.

Tornado, Woodbury

When
December 15, 4:35 PM CST to 4:39 PM CST
Where
Woodbury County, 3.99 mi E of Moville to 3.94 mi W of Pierson
Rating
EF1
Path length
4.28 mi
Path width
75 yd
Property damage
$200,000
Reported by
NWS Storm Survey
Coordinates
42.505, -95.992

This tornado formed around 4 miles east-northeast of Moville, one-quarter mile east of the intersection of Jasper Avenue and 140th Street. The tornado traveled north-northeast for slightly over 4 and one quarter miles before exiting Woodbury County two miles south of Kingsley, just east of the intersection of Knox Avenue and 100th Street. The tornado continued in Plymouth County for somewhat less than 4 miles before dissipating at 1642CST. In Woodbury County near the touchdown point, a barn roof was collapsed. The tornado continued northeast for around a mile and a half before removing most roof panels from another barn. Near the Plymouth County line, the tornado encountered another farmstead which suffered total destruction of a garage and outbuilding. Numerous larger trees were snapped, and debris from damaged buildings was deposited in the trees. The tornado was rated EF1 while in both Woodbury and Plymouth Counties. The average path width in Woodbury County was 50 yards and the maximum estimated wind speed was 110 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:38 PM CST to 4:39 PM CST
Where
Plymouth County, 1 mi SE of Kingsley
Measured
72 kt (83 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.568, -95.959

An old barn was pushed off its foundation and partially collapsed.

Thunderstorm Wind, Woodbury

When
December 15, 4:38 PM CST to 4:39 PM CST
Where
Woodbury County, 2.36 mi NNE of Danbury
Measured
64 kt (74 mph) estimated gust
Property damage
$10,000
Reported by
NWS Storm Survey
Coordinates
42.263, -95.708

A roof was blown off a shed by thunderstorm winds. Property damage costs are a rough estimate.

Tornado, Plymouth

When
December 15, 4:39 PM CST to 4:42 PM CST
Where
Plymouth County, 1.49 mi SSE of Kingsley to 2.64 mi NE of Kingsley
Rating
EF1
Path length
3.72 mi
Path width
75 yd
Property damage
$50,000
Reported by
NWS Storm Survey
Coordinates
42.561, -95.956

This tornado formed around 4 miles east-northeast of Moville in Woodbury County and entered Plymouth County around two miles south of Kingsley, just east of the intersection of Knox Avenue and 100th Street. Numerous large trees were snapped as the tornado entered Plymouth County. The tornado continued to travel north-northeast to a location around one mile east of Kingsley where several outbuildings were destroyed and large trees snapped. The tornado then turned to a northerly track as it crossed County Road C66, where it damaged several power poles. The tornado traveled another mile and a half parallel to Roosevelt Avenue before it destroyed a hoop barn and removed the steel roof from a corn crib, with debris scattered a half mile to the north. The tornado dissipated after another quarter mile at 1642CST. The tornado was rated EF1 while in both Woodbury and Plymouth Counties. The average path width in Plymouth County was 50 yards and the maximum estimated wind speed was 105 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:39 PM CST to 4:40 PM CST
Where
Plymouth County, 0.4 mi SSE of Kingsley
Measured
78 kt (90 mph) estimated gust
Property damage
$20,000
Reported by
NWS Storm Survey
Coordinates
42.575, -95.966

Thunderstorm winds ripped a porch overhang off the exposed south-facing side of a house, with debris impacting a fence and home north of this location. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:39 PM CST to 4:40 PM CST
Where
Plymouth County, 0.43 mi SE of Kingsley
Measured
72 kt (83 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.575, -95.965

South-facing door of outbuilding was buckled by thunderstorm winds, which resulted in failure of the east wall of the building. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:40 PM CST to 4:41 PM CST
Where
Plymouth County, 0.66 mi E of Kingsley
Measured
82 kt (94 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.581, -95.957

Thunderstorm winds destroyed two farm outbuildings and flipped a truck on its side. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:40 PM CST to 4:41 PM CST
Where
Plymouth County, 0.82 mi NE of Kingsley
Measured
83 kt (96 mph) estimated gust
Property damage
$35,000
Reported by
NWS Storm Survey
Coordinates
42.588, -95.958

Thunderstorms winds caused failure of a south-facing door which resulted in uplift of numerous roof panels and removal of insulation. Debris was deposited to the north and northwest of the building amongst several large trees which were snapped. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:41 PM CST to 4:42 PM CST
Where
Plymouth County, 2.21 mi E of Kingsley
Measured
74 kt (85 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.575, -95.927

An old barn was destroyed by thunderstorms winds. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:41 PM CST to 4:42 PM CST
Where
Plymouth County, 2.36 mi E of Kingsley
Measured
72 kt (83 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.576, -95.924

Thunderstorm winds peeled back large sections of north-facing roof on a hog confinement building. Property damage costs are a rough estimate.

Tornado, Ida

When
December 15, 4:42 PM CST to 4:51 PM CST
Where
Ida County, 3.9 mi WSW of Battle Creek to 3.46 mi SSE of Holstein
Rating
EF1
Path length
13 mi
Path width
75 yd
Property damage
$200,000
Reported by
NWS Storm Survey
Coordinates
42.293, -95.667

A tornado formed in an open field between 280th and 290th Streets near the Woodbury and Ida County line southwest of Battle Creek. The tornado tracked northeast for around one mile before it removed shingles from a house southwest of Battle Creek. As the tornado continued northeast, four additional farmsteads were impacted with|several outbuildings damaged or destroyed. Several trees were damaged and a few power poles were snapped north of Battle Creek. The tornado crossed U.S. Highway 59 just north of 190th Street, and lifted approximately 7 miles north of Ida Grove. The average path width was 50 yards and the maximum estimated wind speed was 100 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:44 PM CST to 4:45 PM CST
Where
Plymouth County, 2.92 mi ENE of Kingsley
Measured
69 kt (79 mph) estimated gust
Property damage
$20,000
Reported by
NWS Storm Survey
Coordinates
42.589, -95.914

Thunderstorm winds damaged the top section of a barn, also leaning toward the north. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:44 PM CST to 4:45 PM CST
Where
Plymouth County, 4.19 mi NE of Kingsley
Measured
65 kt (75 mph) estimated gust
Property damage
$25,000
Reported by
NWS Storm Survey
Coordinates
42.627, -95.918

Thunderstorm winds caused extensive damage to an outbuilding with an open side toward the southeast. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 4:46 PM CST to 4:47 PM CST
Where
Cherokee County, 4.56 mi S of Fielding
Measured
74 kt (85 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.604, -95.801

Thunderstorm winds caused the collapse of a brick gable on the west side of a building at the Grand Meadow Heritage Center, as well as lesser damage to other buildings. Property damage costs are a rough estimate.

Thunderstorm Wind, Plymouth

When
December 15, 4:47 PM CST to 4:48 PM CST
Where
Plymouth County, 6.83 mi NNE of Kingsley
Measured
64 kt (74 mph) estimated gust
Property damage
$5,000
Reported by
NWS Storm Survey
Coordinates
42.676, -95.938

Thunderstorm winds removed numerous metal panels from a shed roof. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 4:53 PM CST to 4:54 PM CST
Where
Cherokee County, 4.07 mi W of Mary Hill
Measured
83 kt (96 mph) estimated gust
Property damage
$15,000
Reported by
NWS Storm Survey
Coordinates
42.726, -95.760

Thunderstorm winds knocked down a machine shed. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 4:56 PM CST to 4:57 PM CST
Where
Cherokee County, 2.4 mi SW of Meriden
Measured
83 kt (96 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.775, -95.663

Thunderstorms winds removed a portion of the roof of a well-built machine shed. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 4:56 PM CST to 4:57 PM CST
Where
Cherokee County, 0.86 mi SW of Marcus
Measured
70 kt (81 mph) estimated gust
Property damage
$50,000
Reported by
Emergency Manager
Coordinates
42.810, -95.810

Thunderstorm winds removed sections of the roof off a few buildings and blew a semi-truck off the road. Property damage costs are a rough estimate.

Tornado, Ida

When
December 15, 4:58 PM CST to 5:00 PM CST
Where
Ida County, 1.95 mi NNW of Galva to 4.35 mi N of Galva
Rating
EF0
Path length
2.92 mi
Path width
50 yd
Property damage
$75,000
Reported by
NWS Storm Survey
Coordinates
42.526, -95.435

The tornado developed 2 miles north-northwest of Galva, one-half mile southwest of the intersection of 120th Street and Landmark Avenue. The tornado tracked northeast to a farmstead on the northeast corner of the intersection, where a hoop barn was destroyed and the roof partially removed from a residence. The tornado exited Ida County 4 miles north of Galva just east of Marshal Avenue at 1700CST. The tornado clipped the far southeast corner of Cherokee County, then entered Buena Vista County at 1701CST, where the tornado lifted one mile southwest of Alta at 1706CST. The tornado was rated EF0 in Ida County, EFU in Cherokee County, and EF1 in Buena Vista County. The average path width in Ida County was 50 yards and the maximum estimated wind speed was 85 mph. Property damage costs are a rough estimate.

Tornado, Cherokee

When
December 15, 4:59 PM CST to 5:07 PM CST
Where
Cherokee County, 6.59 mi SSW of Aurelia to 4.42 mi NNE of Aurelia
Rating
EF1
Path length
11.16 mi
Path width
250 yd
Property damage
$1.0 million
Reported by
NWS Storm Survey
Coordinates
42.635, -95.489

The tornado spun up 7 miles south-southwest of Aurelia just west of the intersection of T Avenue and 610th Street. The tornado moved either northeast or north-northeast along its track and exited Cherokee County at 1707CST near the intersection of 510th Street and 10th Avenue. The tornado continued northeast and lifted one mile south of the Buena Vista County Conservation Park at 1712CST.

Shortly after touchdown, the tornado partially collapsed the roof on a hog confinement which killed 13 hogs. Debris from this building was strewn for one to two miles to the northeast. On a northeastward track, another animal confinement farm was struck by the tornado after a couple minutes which resulted in loss of several roof panels on multiple buildings. At this point the tornado shifted path toward more of a north-northeast direction and moved into Aurelia. A drying unit was removed from the top of a grain elevator on the south edge of town. Most of the damage throughout the eastern half of Aurelia was snapped trees, which caused collateral damage to numerous roofs and windows along the path. The tornado moved through the golf course snapping and uprooting numerous trees. The tornado continued with a shift to a more northeast track, and destroyed a barn and three outbuildings along 535th Street northeast of Aurelia. Additional damage occurred to a machine shed and large trees along the Cherokee and Buena Vista County line. The tornado was rated EF1 in both Cherokee and Buena Vista Counties. The average path width was 150 yards in Cherokee County and the maximum estimated wind speed was 110 mph. Property damage costs are a rough estimate.

Tornado, Cherokee

When
December 15, 5:00 PM CST to 5:01 PM CST
Where
Cherokee County, 10.99 mi S of Aurelia to 9.57 mi SSE of Aurelia
Rating
EFU
Path length
1.81 mi
Path width
50 yd
Reported by
NWS Storm Survey
Coordinates
42.562, -95.405

This is the second segment of a tornado which developed 2 miles north-northwest of Galva at 1658CST, and entered Cherokee County 4 miles north of Galva just east of Marshal Avenue at 1700CST. The tornado tracked over open farmland in extreme southeast Cherokee County with no damage indicators, before it entered Buena Vista County at 1701CST, where the tornado lifted one mile southwest of Alta at 1706CST. The tornado was rated EF0 in Ida County, EFU in Cherokee County, and EF1 in Buena Vista County. The average path width in Cherokee County was estimated at 50 yards.

Tornado, Buena Vista

When
December 15, 5:01 PM CST to 5:06 PM CST
Where
Buena Vista County, 1.11 mi SSW of Hanover to 1.46 mi WSW of Alta
Rating
EF1
Path length
6.37 mi
Path width
75 yd
Property damage
$200,000
Reported by
NWS Storm Survey
Coordinates
42.585, -95.388

This is the third segment of a tornado which developed 2 miles north-northwest of Galva at 1658CST, and tracked northeast through extreme southeast Cherokee County. The tornado entered Buena Vista County at 1701CST, one-half mile south of the intersection of 10th Avenue and 640th Street. Along 640th Street, the tornado destroyed two outbuildings on a farmstead and damaged three others, removed a chimney from the roof of the residence, downed several light poles, and snapped and uprooted several large trees. Numerous other large trees were snapped or uprooted as the tornado tracked northeast over the next two miles, before damaging the roof of a hog confinement along 620th Street between 20th and 30th Avenues. Several houses lost shingles and siding, with occasional tree damage before the tornado lifted one mile southwest of Alta at 1706CST. The tornado was rated EF0 in Ida County, EFU in Cherokee County, and EF1 in Buena Vista County. The average path width in Buena Vista County was 50 yards and the maximum estimated wind speed was 100 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Buena Vista

When
December 15, 5:01 PM CST to 5:02 PM CST
Where
Buena Vista County, 0.67 mi SSE of Hanover
Measured
64 kt (74 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.591, -95.375

Several large branches were downed by thunderstorm winds.

Thunderstorm Wind, Cherokee

When
December 15, 5:02 PM CST to 5:03 PM CST
Where
Cherokee County, 0.9 mi S of Aurelia
Measured
87 kt (100 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.707, -95.431

Three empty railcars were blown over by thunderstorm winds.

Thunderstorm Wind, Cherokee

When
December 15, 5:02 PM CST to 5:03 PM CST
Where
Cherokee County, 0.97 mi S of Aurelia
Measured
87 kt (100 mph) estimated gust
Property damage
$20,000
Reported by
NWS Storm Survey
Coordinates
42.706, -95.429

A half-dozen power poles were snapped off at the ground by thunderstorm winds. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 5:02 PM CST to 5:03 PM CST
Where
Cherokee County, 1.14 mi SSW of Aurelia
Measured
78 kt (90 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.706, -95.442

Thunderstorm winds blew in the south facing doors of a metal shed, which caused complete removal of the roof. Property damage costs are a rough estimate.

Thunderstorm Wind, Cherokee

When
December 15, 5:03 PM CST to 5:04 PM CST
Where
Cherokee County, 0.43 mi SSE of Aurelia
Measured
78 kt (90 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.714, -95.428

Thunderstorm winds resulted in failure of garage doors, with removal of walls and roof of half the building. Debris was thrown north and northwest into several homes. Property damage costs are a rough estimate.

Tornado, Cherokee

When
December 15, 5:05 PM CST to 5:08 PM CST
Where
Cherokee County, 1 mi SW of Larrabee to 2.88 mi NNE of Larrabee
Rating
EF1
Path length
3.84 mi
Path width
75 yd
Property damage
$250,000
Reported by
NWS Storm Survey
Coordinates
42.858, -95.541

This tornado formed on the southeast fringes of Larrabee, just south of 455th Street. As the tornado crossed 455th Street, it quickly destroyed four silos, a shed and a chicken barn. The tornado traveled northeast over open fields before a few trees were snapped and the east wall of a barn was pulled away along R Avenue just south of 430th Street. The tornado exited Cherokee County around 4 miles south of Sutherland, one-half mile east of the intersection of Tyler Avenue and 420th Street. The tornado continued in O'Brien County for almost 4 miles before dissipating two miles southeast of Sutherland at 1711CST. The tornado was rated EF1 while in both Cherokee County and O'Brien County. The average path width in Cherokee County was 50 yards and the maximum estimated wind speed was 105 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Buena Vista

When
December 15, 5:07 PM CST to 5:08 PM CST
Where
Buena Vista County, 2.72 mi WNW of Storm Lake Arpt
Measured
56 kt (64 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.614, -95.300

Thunderstorm winds downed several large tree branches.

Tornado, Buena Vista

When
December 15, 5:07 PM CST to 5:12 PM CST
Where
Buena Vista County, 8.58 mi NNW of Alta to 4.28 mi W of Linn Grove
Rating
EF1
Path length
6.94 mi
Path width
150 yd
Property damage
$100,000
Reported by
NWS Storm Survey
Coordinates
42.776, -95.388

The tornado which spun up 7 miles south-southwest of Aurelia continued into Buena Vista County at 1707CST near the intersection of 510th Street and 10th Avenue. The tornado continued northeast and lifted one mile south of the Buena Vista County Conservation Park at 1712CST. Along the track, the tornado caused siding and roof damage to outbuildings near 20th Ave and 490th Street, and removed walls of a machine shed along 480th Street west of 30th Avenue. Numerous wooden power poles were snapped along 470th and 460th Streets. The tornado was rated EF1 in both Cherokee and Buena Vista Counties. The average path width was 75 yards in Buena Vista County and the maximum estimated wind speed was 110 mph. Property damage costs are a rough estimate.

Tornado, O'Brien

When
December 15, 5:08 PM CST to 5:11 PM CST
Where
O'Brien County, 3.31 mi SSE of Calumet to 2.2 mi SE of Sutherland
Rating
EF1
Path length
3.85 mi
Path width
100 yd
Property damage
$50,000
Reported by
NWS Storm Survey
Coordinates
42.910, -95.514

This tornado formed on the southeast edge of Larrabee in Cherokee County, just south of 455th Street. The tornado entered O'Brien County around 4 miles south of Sutherland, one-half mile east of the intersection of Tyler Avenue and 420th Street. The tornado continued northeast in O'Brien County for almost 4 miles, and resulted in only sporadic tree damage before destroying a shed and scattered debris across State Highway 10 two miles south-southeast of Sutherland. The tornado tore part of a roof off a shed shortly before it dissipated two miles southeast of Sutherland at 1711CST. The tornado was rated EF1 while in both Cherokee County and O'Brien County. The average path width in O'Brien County was 75 yards and the maximum estimated wind speed was 105 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Buena Vista

When
December 15, 5:08 PM CST to 5:09 PM CST
Where
Buena Vista County, 1.04 mi N of Storm Lake Arpt
Measured
66 kt (76 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.615, -95.250

A large tree was uprooted by thunderstorm winds.

Thunderstorm Wind, O'Brien

When
December 15, 5:11 PM CST to 5:12 PM CST
Where
O'Brien County, 0.43 mi ENE of Sutherland
Measured
65 kt (75 mph) estimated gust
Property damage
$30,000
Reported by
NWS Storm Survey
Coordinates
42.972, -95.492

Thunderstorm winds snapped several large trees and limbs, which fell and destroyed the roof of a machine shed. Property damage costs are a rough estimate.

Thunderstorm Wind, O'Brien

When
December 15, 5:12 PM CST to 5:13 PM CST
Where
O'Brien County, 2.63 mi ENE of Sutherland
Measured
61 kt (70 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.983, -95.451

Thunderstorm winds downed severe large diameter tree limbs.

Thunderstorm Wind, Clay

When
December 15, 5:14 PM CST to 5:15 PM CST
Where
Clay County, 0.76 mi S of Peterson
Measured
76 kt (87 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.909, -95.350

Thunderstorm winds snapped a large pine tree.

Thunderstorm Wind, Clay

When
December 15, 5:14 PM CST to 5:15 PM CST
Where
Clay County, 2.76 mi ESE of Peterson
Measured
65 kt (75 mph) estimated gust
Reported by
Emergency Manager
Coordinates
42.904, -95.300

Large tree limbs were downed by thunderstorm winds.

Thunderstorm Wind, Clay

When
December 15, 5:14 PM CST to 5:15 PM CST
Where
Clay County, 4.23 mi ESE of Peterson
Measured
56 kt (64 mph) estimated gust
Reported by
NWS Storm Survey
Coordinates
42.898, -95.272

Thunderstorm winds downed several large tree limbs.

Tornado, Buena Vista

When
December 15, 5:18 PM CST to 5:22 PM CST
Where
Buena Vista County, 0.28 mi N of Rembrandt to 1.67 mi NE of Sioux Rapids
Rating
EF2
Path length
4.77 mi
Path width
100 yd
Property damage
$250,000
Reported by
NWS Storm Survey
Coordinates
42.834, -95.171

The tornado spun up just north of Rembrandt at 1718CST near the intersection of 120th Avenue and 470th Street. The tornado tracked northeast, and dissipated near the Little Sioux River one mile east of Sioux Rapids at 1722CST. A residence near the touchdown had siding and roofing torn from the home, along with snapped large pine trees. Along 460th Street just west of U.S. Highway 71, several large wooden power poles were snapped. The tornado continued northeast, crossing U.S. 71 one-half mile north of 460th Street where it destroyed several small buildings. More power poles were snapped along 450th Street east of U.S. 71, with the final damage noted in snapped trees along the Little Sioux River east of Sioux Rapids. The average path width was 75 yards and the maximum estimated wind speed was 115 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Clay

When
December 15, 5:23 PM CST to 5:25 PM CST
Where
Clay County, 2.43 mi SE of Royal
Measured
70 kt (81 mph) estimated gust
Property damage
$25,000
Reported by
Emergency Manager
Coordinates
43.042, -95.251

Thunderstorm winds knocked down an old barn, with several other outbuildings damaged. Property damage costs are a rough estimate.

Thunderstorm Wind, Clay

When
December 15, 5:24 PM CST to 5:25 PM CST
Where
Clay County, 1.81 mi S of Maclay
Measured
64 kt (74 mph) estimated gust
Reported by
Emergency Manager
Coordinates
42.944, -95.074

Thunderstorm winds snapped and uprooted several trees and tipped over a trailer.

Thunderstorm Wind, Clay

When
December 15, 5:25 PM CST
Where
Clay County, 2.52 mi E of Royal
Measured
65 kt (75 mph) estimated gust
Reported by
Emergency Manager
Coordinates
43.070, -95.230

Thunderstorm winds downed a large pine tree.

Thunderstorm Wind, Clay

When
December 15, 5:30 PM CST to 5:32 PM CST
Where
Clay County, 1.26 mi SSW of Spencer
Measured
70 kt (81 mph) estimated gust
Reported by
Emergency Manager
Coordinates
43.134, -95.162

Numerous large trees were downed by thunderstorm winds in Spencer.

Thunderstorm Wind, Dickinson

When
December 15, 5:35 PM CST to 5:36 PM CST
Where
Dickinson County, 8.17 mi WSW of West Okoboji
Measured
52 kt (60 mph) estimated gust
Reported by
Emergency Manager
Coordinates
43.290, -95.310

Several tree limbs were broken by thunderstorm winds.

Tornado, Dickinson

When
December 15, 5:39 PM CST to 5:43 PM CST
Where
Dickinson County, 5.47 mi SE of Fuller Fld Arpt to 3.21 mi E of Fuller Fld Arpt
Rating
EF1
Path length
3.96 mi
Path width
50 yd
Property damage
$200,000
Reported by
Emergency Manager
Coordinates
43.265, -95.088

A tornado spun up 3 miles east-northeast of Fostoria one-half mile south of 260th Street east of 250th Avenue. The tornado tracked north just east of 250th Avenue, and snapped several power poles along 260th and 250th Streets. Two farms between 250th and 240th Streets were struck by the tornado, which peeled back the roof of an outbuilding and damaged several large trees. The most significant damage occurred along 235th Street where a portion of the south-facing roof was removed from a house and an outbuilding to the north of the house was destroyed. The tornado tracked through open fields for another mile before it lifted 2 miles east of Milford. The average path width was 25 yards and the maximum estimated wind speed was 100 mph. Property damage costs are a rough estimate.

Thunderstorm Wind, Dickinson

When
December 15, 5:49 PM CST to 5:50 PM CST
Where
Dickinson County, 0.69 mi S of Spirit Lake
Measured
65 kt (75 mph) estimated gust
Property damage
$10,000
Reported by
Public
Coordinates
43.420, -95.100

Thunderstorm winds downed several power poles. Property damage costs are a rough estimate.

Thunderstorm Wind, Dickinson

When
December 15, 5:52 PM CST to 5:53 PM CST
Where
Dickinson County, 1.51 mi E of Superior
Measured
61 kt (70 mph) estimated gust
Property damage
$25,000
Reported by
Emergency Manager
Coordinates
43.430, -94.950

Large branches were downed by thunderstorm wind gusts. Numerous shingles were blown off the roof, and the garage was blown off its foundation. Property damage costs are a rough estimate.

High Wind, Sioux

When
December 15, 7:55 PM CST to 11:55 PM CST
Where
Sioux forecast zone
Measured
58 kt (67 mph) measured gust
Reported by
AWOS
Coordinates
43.083, -96.178 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 59 mph during the evening, with a peak wind gust of 67 mph at the Sioux County Regional Airport (KSKX).

High Wind, Woodbury

When
December 15, 8:20 PM CST to 10:20 PM CST
Where
Woodbury forecast zone
Measured
58 kt (67 mph) measured gust
Reported by
ASOS
Coordinates
42.390, -96.045 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 45 mph during the evening, with a peak wind gust of 67 mph at the Sioux Gateway Airport (KSUX).

High Wind, Ida

When
December 15, 8:30 PM CST to December 16, 12:00 AM CST
Where
Ida forecast zone
Measured
59 kt (68 mph) measured gust
Reported by
AWOS
Coordinates
42.387, -95.513 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 52 mph during the evening and into the early overnight, with a peak wind gust of 68 mph at the Storm Lake Airport (KSLB).

High Wind, Plymouth

When
December 15, 8:35 PM CST to 8:55 PM CST
Where
Plymouth forecast zone
Measured
55 kt (63 mph) measured gust
Reported by
AWOS
Coordinates
42.738, -96.214 (the zone’s center; the record gives no point)

Sustained winds briefly reached around 40 mph during the evening, with a peak wind gust of 63 mph at Le Mars Municipal Airport (KLRJ).

High Wind, O'Brien

When
December 15, 8:35 PM CST to December 16, 12:00 AM CST
Where
O'Brien forecast zone
Measured
54 kt (62 mph) measured gust
Reported by
AWOS
Coordinates
43.084, -95.625 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 50 mph during the evening, with a peak wind gust of 62 mph at the Sheldon Regional Airport (KSHL).

High Wind, Cherokee

When
December 15, 8:40 PM CST to 11:45 PM CST
Where
Cherokee forecast zone
Measured
39 kt (45 mph) measured sustained
Reported by
Mesonet
Coordinates
42.736, -95.624 (the zone’s center; the record gives no point)

Sustained winds reached 45 mph at station MCSI4 near 10 miles south of Marcus.

High Wind, Clay

When
December 15, 8:45 PM CST to December 16, 1:00 AM CST
Where
Clay forecast zone
Measured
63 kt (72 mph) measured gust
Reported by
ASOS
Coordinates
43.083, -95.151 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 52 mph during the evening and into the early overnight, with a peak wind gust of 72 mph at the Spencer Municipal Airport (KSPW).

High Wind, Buena Vista

When
December 15, 9:00 PM CST to December 16, 1:00 AM CST
Where
Buena Vista forecast zone
Measured
59 kt (68 mph) measured gust
Reported by
AWOS
Coordinates
42.736, -95.151 (the zone’s center; the record gives no point)

Sustained winds reached 40 to 52 mph during the evening and into the early overnight, with a peak wind gust of 68 mph at the Storm Lake Airport (KSLB).

High Wind, Osceola

When
December 15, 9:00 PM CST to December 16, 1:00 AM CST
Where
Osceola forecast zone
Measured
37 kt (43 mph) measured sustained
Reported by
Mesonet
Coordinates
43.379, -95.624 (the zone’s center; the record gives no point)

Sustained winds reached 43 mph at station SBEI4 6 miles west southwest of Ocheyedan.

High Wind, Lyon

When
December 15, 9:00 PM CST to 11:00 PM CST
Where
Lyon forecast zone
Measured
40 kt (46 mph) measured sustained
Reported by
Mesonet
Coordinates
43.381, -96.210 (the zone’s center; the record gives no point)

Sustained winds reached 46 mph at station DONI4 near Doon.

High Wind, Dickinson

When
December 15, 10:00 PM CST to 10:15 PM CST
Where
Dickinson forecast zone
Measured
51 kt (59 mph) measured gust
Reported by
Mesonet
Coordinates
43.378, -95.151 (the zone’s center; the record gives no point)

Sustained winds briefly approached 40 mph during the evening, with a peak wind gust of 59 mph at a Citizen Weather Observer Program (CWOP) station near Milford.

What these are

Tornado
A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
High Wind
Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Iowa in 2021Every state in 2021This day in weather historyThe tornado archive for Iowa, 2021Warnings in Iowa, December 2021

Sources

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: 1000137, 1002015, 999589, 1002018, 999591, 1000520, 999598, 1002020, 1000134, 1000135, 1000136, 1002025, 1000140, 1000154, 1000202, 1000139, 1000160, 1000162, 1000167, 1000170, 1000172, 1000173, 1000219, 1000175, 1000180, 1000232, 1000197, 1000234, 1000253, 1002035, 1000303, 1000396, 1000312, 1000338, 1000340, 1000489, 1000499, 1000509, 1000508, 1000268, and more.