One of the most prolific summer tornado outbreaks in the Northern Great Plains of the United States on record occurred from June 16–18, 2010. The outbreak began on June 16, with several tornadoes in South Dakota and Montana. The most intense storms took place the following day across much of eastern North Dakota and much of Minnesota. The system produced 93 tornadoes reported across four states while killing three people in Minnesota. Four of the tornadoes were rated as EF4 on the Enhanced Fujita scale, one in eastern North Dakota, and three in west-central and southern Minnesota. It was the most violent tornadoes in a 24-hour period since there were five within 15 hours in the 2008 Super Tuesday tornado outbreak.
Significant damage was reported west of Grand Forks, North Dakota, and in the Wadena, Minnesota, area, and a tornado emergency was issued for areas north of Wadena and again later for areas near Plummer, Minnesota, where significant damage was reported. Much of Wadena was destroyed by its tornado. Three people were killed; one in Almora, Minnesota, one in Mentor, Minnesota; and a third in Freeborn County, Minnesota. This was the region's first major tornado outbreak of the year and one of the largest on record in the region, comparable to a similar outbreak in June 1992. The 48 tornadoes that touched down in Minnesota on June 17 marked the most active single day in the state's history. June 17 was the second largest tornado day on record in the meteorological summer, behind the most prolific day of the 2003 South Dakota tornado outbreak on June 24, 2003.
Associated with the tornado outbreak was a destructive derecho, spawned by a cluster of thunderstorms over Nebraska that developed into a squall line over Iowa during the morning of June 18. This line swept eastward bringing 75 mph winds to Des Moines, Iowa and 60 mph winds to the Quad Cities. It continued across northern Illinois and extreme southern Wisconsin hitting Chicago at 1 pm bringing 70-80 mph winds to the city. The line continued into Michigan and Indiana dramatically growing in size, stretching from Danville, IL to Fort Wayne, IN to Lansing, MI. A 90 mph wind gust was recorded in La Porte, IN. Behind this line, a second squall line developed over northeast Iowa and traveled across the same areas as the first hitting the Quad Cities 6 hours after the first one and Chicago 5 hours after the first line. The first line began dissipating around 9pm EDT over Ohio while the second one would fall below severe limits. 2 people died in the first line while it is unclear if the second one met derecho criteria.
Meteorological synopsis June 16
On June 16, 2010, an upper-level area of low pressure and associated trough moved southeastward across the Rocky Mountains into the Great Plains. Along the base of the trough, the presence of a strong mid-level jet stream provided significant instability; however, warm-air aloft was expected to limit the extent of convective development. Moderate to strong deep layer wind shear along with steep lapse rates would allow for the development of supercell thunderstorms with large hail (greater than in diameter). In light of this, the Storm Prediction Center issued a slight-risk of severe weather for portions of Colorado, Montana, Nebraska, North Dakota, South Dakota and Wyoming.
June 17–18 The Storm Prediction Center issued a moderate risk of severe weather for June 17, 2010, citing a 10% threat for tornadoes, 45% threat for large hail and 45% threat for damaging wind, initially thinking tornadoes would quickly reform into a straight-line wind event. The moderate risk area extended from around Fargo, North Dakota, to Des Moines, Iowa, and Omaha, Nebraska, including the Twin Cities area, with a slight risk area extending across the Upper Midwest. Surface dew points reached the low 70s °F (low 20s °C) with surface temperatures well into 80s °F (near 30 °C) across Minnesota. Surface-based CAPE values were forecast to reach 2000–3000 J/kg.
The first tornadoes were reported across eastern North Dakota during the mid-afternoon where a tornado watch was issued for most of the state as well as extreme northwestern Minnesota closer to the Manitoba and northwestern Ontario borders where many tornadoes, some strong to violent, touched down late that afternoon. After several tornadoes affected areas near the Grand Forks area and closer to the Canada–US border, the activity eventually shifted into northwestern Minnesota by the late afternoon while storms over northern Iowa moved across southern Minnesota near the Interstate 90 corridor producing many tornadoes. Other storms developed over central Minnesota near Interstate 94 but most activity missed the Twin Cities area. The supercells eventually reached the Wisconsin border later that evening and reformed into a squall line, rapidly ending the severe weather outbreak. Isolated tornado reports also occurred across Wisconsin and Iowa. Three people were killed according to KARE-TV including one in Mentor (Polk County), one in Almora (Otter Tail County) and one near Albert Lea (Freeborn County) an area that sustained heavy damage from a long-tracked EF4 tornado. Large tornadoes were sighted in Kiester in Faribault County and near Ellendale and Blooming Prairie in Steele County, Minnesota.
The town of Wadena was also hard hit; the high school was heavily damaged by a tornado that prompted a tornado emergency. Extensive damage was also reported in various other communities in Minnesota as well as in North Dakota from either tornadoes or widespread damaging winds such as in the Rochester, Minnesota, area where several buildings, including homes, were heavily damaged on the northern side of the town. A local emergency was declared in Rochester by the mayor following the storms. The three tornado fatalities in Minnesota were the most for a single outbreak since 1978, and the three EF4 tornadoes were the most on a single day since 1967.
A moderate risk of severe weather was issued for parts of southern Iowa, northern Missouri and northwestern Illinois during the mid-morning of June 18 citing mostly the threat for damaging winds (45%), though a few tornadoes would be possible as CAPE values of 4000 j/kg were forecast across the Missouri and mid-Mississippi Valleys, especially behind the main derecho. Such did not materialize, however.
Confirmed tornadoes
Almora–Deer Creek–Bluffton, Minnesota
At approximately 3:43 p.m. CDT (2043 UTC), a long-lived tornado touched in northern Douglas County, southeast of Urbank. Numerous trees were broken and snapped at EF1 intensity at this point. The tornado would also display strong multiple-vortex characteristics at this time, as it began to cross over into Otter Tail County to the north, where it would cause immense damage across eastern parts of the county. The tornado caused mostly insignificant damage as it passed west of Parkers Prairie, until it approached the small community of Almora. Just to the south, a farmhouse was destroyed, where a woman was killed. The tornado would approach Almora to the east, narrowly avoiding a direct hit, though some homes on the eastern side suffered some levels of damage.
The tornado would head more northeast and widen to or 1.3 mi wide as it began to pass southeast of Deer Creek. The massive tornado would level many rural homes in the vicinity, as it continued to intensify even further. Along a county highway, the tornado would become violent as it wiped seven farmhouses off their foundations at EF4 intensity southwest of Bluffton. Many trees were extensively debarked and outbuildings were blown away as the tornado headed due north, passing west of Bluffton and demolishing more farmsteads.
After several miles, the storm would start to weaken. At 4:45 p.m. CDT (2145 UTC) the tornado would dissipate northeast of New York Mills, after being on the ground for more than an hour, and tracking for .*
It was the first of four tornadoes to be classified as EF4 during the historic outbreak. It as well was it the first time a violent tornado struck the state of Minnesota, since the F4 tornado that struck Granite Falls on July 25, 2000. The Almora–Bluffton tornado was also the longest tracked, and longest lived event of the entire June 17 outbreak, as it traversed for nearly through for almost the entire eastern side of Otter Tail County, in the west-central parts of Minnesota. It was also the largest tornado of the outbreak by width, as it spanned over a mile and a quarter along portions of its track. A separate and long-lived supercell produced another violent EF4 tornado, with that one touching down a few minutes after this tornado passed through in the same area, crossing over into neighboring Wadena County and impact Wadena proper.
This tornado was featured on the Storm Chasers TV series, on the Discovery Channel. Storm chaser Reed Timmer and Team Dominator in their Dominator 1 interceptor vehicle, were having a competitive showdown with Sean Casey and his Tornado Intercept Vehicle (TIV) crew in their TIV 2, as they were intercepting the EF4 Almora–Bluffton tornado.
Mayville–Holmes–Thompson, North Dakota
This narrow but violent drillbit tornado touched down north to northeast of Mayville, at 3:49 p.m. CDT (2049 UTC). Approximately to the north of town in rural Traill County, the tornado impacted a farm shop, completely destroying the structure. One man on the property was inside and was covered under piles of rubble, surviving with cuts to his hand. The tornado caused severe damage to the nearby outbuildings on the property, but didn't disturb the contents of a storage building, nor a desk that was located in the middle of the shop.
The tornado continued its journey, heading north and approaching the Traill–Grand Forks County border, to the east of Hatton. Many trees in shelterbelts and in farmsteads were snapped, uprooted, or sheared off. Law enforcement from the Traill County Sheriff's Office recorded the tornado as it was seen churning across the fields. The tornado began to occlude, but intensify even further as it began approaching the Holmes area in Grand Forks County.
Along one road in the vicinity, nine miles west to southwest of Thompson, the tornado would impact a farmstead at peak intensity. The main residence was completely swept off its foundation, leaving only an empty basement behind, and numerous trees and outbuildings nearby were destroyed. A chair was found thrown into a tree, while another had a computer hard drive found embedded within. After exiting the property, the tornado would continue to weaken and after two miles traveling, would dissipate to the west of Thompson at 4:18 p.m. CDT (2118 UTC).*
This tornado traveled for across the two counties, and lasted for nearly half an hour. It was the only violent tornado of the outbreak to occur in North Dakota. It was also the highest rated, reaching winds in the upper echelon of EF4 intensity. It was one of the last violent (EF4+) tornadoes to occur in the state of North Dakota, until an EF5 tornado occurred over 15 years, and 3 days later on June 20, 2025.
Stevens County–Cass County, Minnesota supercell
Around 3:20 p.m. CDT (2120 UTC), a supercell thunderstorm developed over Stevens County, Minnesota, and initially tracked north-northeastward before turning fully northeast. Once over Otter Tail County, the storm intensified and a brief EF1 tornado touched down around 4:48 pm CDT (2248 UTC) southeast of Deer Creek. The rear-flank downdraft of the storm quickly obscured the tornado from view; however, it was later determined the tornado was on the ground for , uprooting small trees and snapping limbs of larger ones. Two minutes prior at 4:56 pm CDT (2256 UTC), a tornado warning was issued for portions of Becker, Clearwater, Hubbard, Otter Tail and Wadena Counties.