SPC outlooks on June 17, 2010.

Day 1 06z categorical outlooks.

Day 1 06z tornado outlooks.

Day 1 06z hail outlooks.

Day 1 06z wind outlooks.

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 2 in (5.1 cm) 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.^[8]

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.^[9]

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.^[10] 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)^{[citation needed]} and one near Albert Lea (Freeborn County) an area that sustained heavy damage from a long-tracked EF4 tornado.^{[citation needed]} Large tornadoes were sighted in Kiester in Faribault County and near Ellendale and Blooming Prairie in Steele County, Minnesota.^[11]

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.^[11] 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.^[12]

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.^[13] Such did not materialize, however.

Almora–Deer Creek–Bluffton, Minnesota

The massive EF4 tornado at peak width.
Meteorological history
Formed	June 17, 2010, 3:43 p.m. CDT (UTC−05:00)
Dissipated	June 17, 2010, 4:45 p.m. CDT (UTC−05:00)
Duration	1 hour, 2 minutes
EF4 tornado
on the Enhanced Fujita scale
Highest winds	175 mph (282 km/h)
Overall effects
Fatalities	1
Injuries	5

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.^[14][15]

The tornado would head more northeast and widen to 2,288 yd (2,092 m) 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.^[16][17]

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 39.56 mi (63.67 km).^[18]

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 40 mi (64 km) 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.^[19][20] 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.^[18][17]

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.^[21][22]

Mayville–Holmes–Thompson, North Dakota

A photo of the violent tornado near Holmes.
Meteorological history
Formed	June 17, 2010, 3:49 p.m. CDT (UTC−05:00)
Dissipated	June 17, 2010, 4:18 p.m. CDT (UTC−05:00)
Duration	29 minutes
EF4 tornado
on the Enhanced Fujita scale
Highest winds	185 mph (298 km/h)
Overall effects
Fatalities	0
Injuries	1

This narrow but violent drillbit tornado touched down north to northeast of Mayville, at 3:49 p.m. CDT (2049 UTC). Approximately 5.5 mi (8.9 km) 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.^[23][24]

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.^[25] The tornado began to occlude, but intensify even further as it began approaching the Holmes area in Grand Forks County.^[26]

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.^[27][28][29] 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).^[26]

This tornado traveled for 17 mi (27 km) 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.^[30][31] 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.^[32]

Stevens County–Cass County, Minnesota supercell

A rain-wrapped EF4 tornado approaching Wadena
Meteorological history
Formed	June 17, 2010, 3:20 p.m. CDT (UTC−05:00)
Dissipated	June 17, 2010, 6:30 p.m. CDT (UTC−05:00)
Duration	3 hours, 10 minutes
EF4 tornado
on the Enhanced Fujita scale
Highest winds	170 mph (270 km/h)
Overall effects
Fatalities	0
Injuries	20
Damage	$32 million (2010 USD)

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 4:58 pm CDT (2258 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 1.5 mi (2.4 km), uprooting small trees and snapping limbs of larger ones.^[34] 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.

A few minutes after the warning was issued, the second and strongest tornado the storm produced, rated low-end EF4 touched down about 3 mi (4.8 km) southwest of the city of Wadena, in Otter Tail County. Within three minutes of forming, this violent multiple vortex tornado rapidly intensified, producing extreme tree damage with many trees snapped or uprooted as it moved northeast. Before crossing the Otter Tail-Wadena County border, the storm's width had reached 1,936 yd (1,770 m), or 1.1 mi.^[36]

The tornado then struck the western side of Wadena, causing widespread severe damage. Two houses were blown away from their foundations and many other houses and businesses were destroyed by this large wedge tornado. Many other structures were damaged to lesser degrees as well. Wadena-Deer Creek Middle/High School lost large sections of its roof and suffered extensive damage to its interior. A bus garage and an apartment complex were also damaged and school buses were thrown into the air. Trees were also debarked and snapped throughout the town. Cars were tossed by the tornado and headstones were toppled at a cemetery in Wadena. About 20 people were injured. Damage from the tornado reached $32 million, making it the most destructive of the outbreak.^[37] In light of the damage in the city, a tornado emergency was declared for Sebeka and Nimrod; however, substantial damage never took place in these areas. Continuing northeastward, the tornado gradually weakened before dissipating at 5:16 pm CDT (2316 UTC), ending its 10 mi (16 km) track.

At 5:30 pm CDT (2230 UTC), a third tornado, rated EF0, touched down within the supercell, this time roughly 1.5 mi (2.4 km) south-southwest of Nimrod. Over the following 18 minutes, this storm made several touchdowns along a 14.8 mi (23.8 km) track that continued into Cass County. Damage from this tornado was largely limited to broken tree limbs.^[39] Continuing northeast, the supercell eventually dissipated over Cass County around 6:30 pm CDT (2330 UTC).

Conger–Albert Lea–Manchester–Hartland, Minnesota

The tornado north of Albert Lea
Meteorological history
Formed	June 17, 2010, 6:33 p.m. CDT (UTC−05:00)
Dissipated	June 17, 2010, 7:15 p.m. CDT (UTC−05:00)
Duration	42 minutes
EF4 tornado
on the Enhanced Fujita scale
Highest winds	175 mph (282 km/h)
Overall effects
Fatalities	1
Injuries	14

This large, violent tornado touched down west of Mansfield at 6:33 p.m. CDT (2333 UTC), and passed by areas west and north of the Albert Lea area, producing very intense damage early in its life where a home on the edge of the circulation sustained roof and siding damage, a barn was destroyed down to its brick foundation, a vehicle was flipped, and some trees showed debarking.

As the tornado intensified further across Freeborn County, it caused extensive crop damage in a wide swath with fields raked down to bare stalks. At several farmsteads, the tornado completely destroyed multiple swine barns, blew away empty grain bins, toppled a tall wind turbine tower, and left soybean fields nearly unrecognizable. The tornado maintained strong intensity while toppling silos, flattening additional farm buildings, and knocking down large numbers of trees.

It then reached its peaked strength north of Conger as it completely destroyed a farmhouse, barn, and other buildings, extensively debarked trees, and tumbled a car more than half a mile into an open field. After slightly weakening, the tornado continued to destroy and severely damage additional homes, barns, and grain bins, including rotating a house off its foundation. Debris from destroyed structures was lofted long distances, with sheet metal carried as far as I-90, which the tornado later crossed while re-intensifying. Several farmsteads suffered total losses in this phase, including homes and multiple barns, and the tornado widened to nearly a mile across.

Farther north, the tornado gradually weakened but continued to damage grain bins, trees, and farm structures before narrowing and dissipating west of Hartland, along a 16.91 mi (27.21 km) path at 7:15 p.m. (0015UTC). One woman was killed inside a manufactured home near . Fourteen people were injured.

The day following the outbreak, the Minnesota National Guard arrived into Wadena to help residents and provide assistance. This was issued by former Minnesota governor Tim Pawlenty in response to the severe tornado and weather outbreak in the region. The Wadena City Council, which consisted of county commissioners from Wadena and Otter Tail counties, declared the city to be a major disaster area. Then preliminary assessments concluded that the tornado significantly damaged about 234 homes and 20 city blocks in southwestern and northwestern Wadena.^[55] On June 22, FEMA and state surveyors assessed the damage in the city, and several counties throughout northwestern and southern Minnesota, whether a major disaster declaration was sufficient to be granted by former US President Barack Obama.^[56] On July 2, the Obama administration granted a federal emergency declaration (FEMA-1921-DR) for Minnesota. Areas that were affected by the severe weather events were Faribault, Freeborn, Olmsted, Polk, Steele, Otter Tail and Wadena counties, as parts of the state were also flooded after the tornadoes, which lasted until June 26.^[57]