June 2010 Northern Plains tornado outbreak explained

June 2010 Northern Plains tornado outbreak
Type:	Tornado outbreak
Active:	June 16 – 18, 2010
Tornadoes:	93 confirmed
Fujitascale:	EF4
Tornado Duration:	56 hours, 52 minutes
Fatalities:	3 fatalities (+ 2 non-tornadic), 43 injuries
Damages:	$117.7 million
Enhanced:	yes
Partof:	the tornado outbreaks of 2010

The June 2010 Northern Plains tornado outbreak was one of the most prolific summer tornado outbreaks in the Northern Great Plains of the United States on record. 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, the most violent tornadoes in a 24-hour period since there were five within 15 hours in the 2008 Super Tuesday tornado outbreak. 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.^[1] 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.

Synopsis

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 2inches 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.^[2]

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.^[3]

The first tornadoes were reported across eastern North Dakota during the mid-afternoon hours 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.^[4] 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 hours 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)^[5] and one near Albert Lea (Freeborn County) an area that sustained heavy damage from a long-tracked EF4 tornado.^[6] Large tornadoes were sighted in Kiester in Faribault County and near Ellendale and Blooming Prairie in Steele County, Minnesota.^[7]

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.^[7] 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.^[8]

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.^[9] Such did not materialize, however.

Confirmed tornadoes

June 16 event

List of reported tornadoes – Wednesday, June 16, 2010
EF#	Location	County	Coord.	Time (UTC)	Path length	Comments/Damage
South Dakota
EF0	S of Red Elm (1st tornado)	Ziebach		2304 – 2305	unknown	Brief tornado touchdown with no damage.^[10]
EF0	S of Red Elm (2nd tornado)	Ziebach		2330 – 2332	unknown	Brief tornado touchdown with no damage.^[11]
EF0	S of Red Elm (3rd tornado)	Ziebach		2340	unknown	Brief tornado touchdown with no damage.
EF0	S of Red Elm (4th tornado)	Ziebach		2341	unknown	Brief tornado touchdown with no damage.
EF1	SW of Dupree (1st tornado)	Ziebach		0022 – 0045	2miles	A brief tornado downed several power lines.^[12]
EF0	SW of Dupree (2nd tornado)	Ziebach		0030	unknown	Satellite tornado to the previous event.
EF2	Dupree area	Ziebach		0033 – 0049	1miles	Considerable damage in the community with several houses heavily damaged, the local community center lost its roof and mobile homes and grain bins were destroyed. Two people were injured and damage amounted to $750,000.^[13]
EF0	WNW of Dupree (1st tornado)	Ziebach		0040 – 0042	unknown	Brief tornado touchdown with no damage.^[14]
EF0	WNW of Dupree (2nd tornado)	Ziebach		0040	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (1st tornado)	Ziebach		0053 – 0058	unknown	Brief tornado touchdown with no damage.^[15]
EF0	NW of Dupree (2nd tornado)	Ziebach		0053	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (3rd tornado)	Ziebach		0053	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (4th tornado)	Ziebach		0054	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (5th tornado)	Ziebach		0056	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (6th tornado)	Ziebach		0058	unknown	Brief tornado touchdown with no damage.
EF0	NW of Dupree (7th tornado)	Ziebach		0058	unknown	Brief tornado touchdown with no damage.
EF2	ENE of Lantry	Dewey		0135 – 0138	unknown	Brief but intense tornado resulted in severe structural damage to two houses and several pole barns were destroyed, killing a horse.^[16]
Montana
EF1	E of Fort Peck	McCone		0256 – 0304	3miles	Storage sheds were damaged and numerous trees were snapped.^[17]
Sources: SPC Storm Reports for 06/16/10, NWS Rapid City, NCDC Storm Data

June 17 event

List of reported tornadoes – Thursday, June 17, 2010
EF#	Location	County	Coord.	Time (UTC)	Path length	Comments/Damage
North Dakota
EF1	SW of Hettinger	Adams		1435	0.6miles	A brief tornado touched down along the southwest side of Hettinger, breaking windows in an apartment building and slightly lifting a car off the ground. Damage from the tornado reached $25,000.^[18] One of two non-supercell tornadoes spawned during the outbreak.^[19]
EF0	E of Noonan	Burke		1931	3.5miles	Brief tornado touchdown near the Canada–US border with known damage.^[20] Second of two non-supercell tornadoes.
EF0	NW of Gackle	Stutsman		1955	3miles	Tornado remained over open country.
EF0	NE of Finley	Steele		2038	4miles	Tornado spotted by off-duty NWS Dodge City meteorologist with no damage.
EF0	NE of Pingree	Stutsman		2044	unknown	Brief tornado touchdown with no damage.
EF4	Thompson area	Traill, Grand Forks		2049-2118	17miles	A house was completely swept away with only an empty basement remaining near Holmes. A welding building and several farm buildings were destroyed. Trees were snapped and debarked, one of which had a metal chair embedded into it. One person sustained minor injuries.
EF1	N of Berea	Barnes		2101	1miles	Several trees and a wooden power pole were knocked down.
EF0	WSW of Dazey	Barnes		2105	unknown	Brief tornado touchdown with no damage.
EF0	E of Sheyenne	Eddy, Benson		2127	1miles	Tornado remained over open country.
EF2	Hope area (1st tornado)	Steele		2128	7miles	Severe tree damage reported at a golf course and on a farm.
EF1	Hope area (2nd tornado)	Steele		2130	7miles	An irrigation system was damaged and trees were knocked down.
EF2	S of Ojata	Grand Forks		2131	7miles	Debris was thrown in the area, including near Grand Forks Air Force Base. Many trees were snapped and a pole barn was destroyed.
EF2	ENE of Hope	Steele		2140	3miles	An abandoned farmhouse was destroyed and several farm buildings were heavily damaged. Trees were also damaged.
EF1	NW of Grand Forks	Grand Forks		2147	10miles	A pole barn was damaged and trees were snapped or uprooted.
EF0	NNE of Sherbrooke	Steele		2202	3miles	Minor damage limited to a few trees.
EF0	N of Dahlen	Nelson		2215	3miles	A few tree limbs were knocked down.
EF1	NE of Poland	Walsh, Marshall (MN)		2221	5miles	Several large trees were snapped along the Red River.
EF0	SE of Orr	Grand Forks		2222	1miles	A few tree limbs were knocked down.
EF0	W of Thompson	Grand Forks		2230	8miles	Intermittent tornado touchdown with minor tree damage.
EF0	E of Gilby	Grand Forks		2237	2miles	Tornado remained over open country.
EF1	W of Fordville	Walsh		2241	2miles	Several trees were snapped or uprooted.
EF1	S of Orr	Grand Forks		2245	4miles	Several trees were snapped or uprooted.
Minnesota
EF0	SW of Fossum	Norman		2028	1miles	Minor tree damage in a cemetery.
EF4		Douglas, Otter Tail		2043-2145	40miles	1 death – Large multiple-vortex tornado flattened several houses and blew them away along Otter Tail County Road 143, one of which had an occupant killed. Numerous other houses were damaged or destroyed. Farm buildings were also obliterated by the tornado, which was up to 1.3miles wide. Trees were also debarked and vehicles were thrown into the air. Five others were injured.
EF0	E of Vergas	Otter Tail		2055	unknown	Brief tornado touchdown with no damage.
EF0	E of Bejou	Mahnomen, Polk		2100	6miles	A few trees were knocked down.
EF1	W of Lake Itasca	Clearwater		2132	1miles	Trees and limbs were snapped along Long Lost Lake.
EF1	NW of Zerkel	Clearwater		2141	3miles	One house sustained minor damage. Extensive tree damage along the path.
EF1	S of Bluffton	Otter Tail		2148	1.5miles	See section on this tornado
EF4	Wadena area	Otter Tail, Wadena		2159-2216	10miles	See section on this tornado
EF0	NW of Elmore	Faribault		2205	3miles	A metal shed was damaged and trees were uprooted.
EF1	SE of Goodridge	Pennington		2207	2miles	Heavy farm equipment was moved around and a few trees were damaged.
EF1	W of Lake George	Hubbard		2217	6miles	Many large trees were snapped or uprooted.
EF0	NW of Winsted	McLeod		2223	0.75miles	Isolated tree and limb damage and minor crop damage.
EF1	SW of Clearbrook	Clearwater		2229	1miles	Several trees and power poles were damaged.
EF0	SSW of Nimrod to SSW of Osnawa	Wadena, Cass		2230	14.8miles	See section on this tornado
EF0	SE of Eagle Lake	Blue Earth		2237	3miles	Two sheds sustained minor damage. Many trees were damaged.
EF0	NE of Elmore	Faribault		2240	1.9miles	Damage mostly to trees from this second tornado in the area.
EF1	NE of Gatzke	Marshall, Roseau		2244	4miles	Numerous trees were snapped or uprooted.
EF0	W of Kabekona Corner	Hubbard		2248	4miles	Damage limited to tree branches.
EF0	W of Benedict	Hubbard		2249	1miles	Damage limited to tree branches.
EF1	Fisher area	Polk		2250	7miles	Well-defined tornado sighted by an off-duty SPC meteorologist. A shed was destroyed and many trees were damaged.
EF0	NE of Clear Lake (1st tornado)	Sherburne		2254	unknown	Brief tornado touchdown with no damage.
EF0	NE of Clear Lake (2nd tornado)	Sherburne		2256	3miles	Numerous trees were snapped by a second tornado that touched down as the first one dissipated.
EF1	N of Buffalo	Wright		2300	5miles	Many trees were damaged, including snapped trunks, around Constance Lake.
EF1	W of Gentilly	Polk		2300	3miles	A grain bin was tossed and trees were uprooted.
EF0	SSW of Bricelyn	Faribault		2305	1miles	Tornado remained over open country.
EF0	N of Angus	Polk		2306	2miles	One house sustained minor damage and a few tree limbs were knocked down.
EF0	SW of Walters	Faribault		2310	unknown	Spotter reported tornado on the ground. No damage reported.
EF2	Kiester area (1st tornado)	Faribault		2313	1miles	Several grain bins were destroyed and many trees were knocked down.
EF3	Mentor area	Polk, Red Lake		2315	15miles	1 death – A Cenex station was hit killing one person. The gas station and four vehicles were destroyed by the multiple-vortex tornado. Many trees, farm buildings and a farm house were also heavily damaged. Cabins, RVs, and cottages were heavily damaged along Maple Lake. Boats and docks were picked up by tornado and tossed.
EF2	Kiester area (2nd tornado)	Faribault		2316	unknown	Tornado quickly developed after the first Keister tornado developed, the two tornadoes merged. Severe tree damage in the area.
EF1	E of Dorothy	Red Lake		2316	2miles	A parked semi-trailer was blown off a highway, injuring the driver.
EF0	E of Kiester	Faribault		2323	unknown	Brief tornado touchdown with no damage.
EF1	N of Radium	Marshall		2326	7miles	Large trees were snapped and a shed was damaged.
EF1	SE of Walters	Faribault, Freeborn		2328	unknown	Brief tornado damaged a few trees.
EF4	W of Albert Lea	Freeborn		2333-0015	20miles	1 death – Dozens of farms were affected and several houses were destroyed or leveled by this large wedge tornado. Some farmsteads were entirely destroyed by the tornado. Three hog confinements were destroyed with several hogs escaping. A wind energy facility was also damaged and vehicles were tossed. There were also additional major infrastructure damage along with gas leaks. Trees were also debarked and many farm structures were destroyed across the county. 14 others were injured, some severely.
EF1	Armstrong	Freeborn		2355	1miles	Satellite tornado related to the Albert Lea tornado. Several grain bins, structures and trees were damaged.
EF3	Ellendale area	Freeborn, Steele		0005	18.7miles	One house and many outbuildings were destroyed and several other houses were damaged. Many trees were damaged, some of which were debarked.
EF1	Clarks Grove area	Freeborn, Steele		0015	12.9miles	Tornado paralleled the Ellendale tornado. Damage to farm houses, many outbuildings (some of which were destroyed) and trees.
EF1	SW of Lerdal	Freeborn		0042	5miles	A barn was destroyed and sheds were damaged.
EF3	W of Hollandale	Freeborn		0047	5miles	One house and many outbuildings were flattened and several other houses were damaged, some severely. Major damage to trees with some debarked.
EF1	WSW of Newry	Freeborn		0103	2miles	Three farm houses were damaged, and numerous sheds and outbuildings were also damaged.
EF0	S of Hill City	Aitkin		0105	1miles	Brief tornado captured by a mobile phone photograph in the Moose Willow State Wildlife Management Area with minimal damage.
EF3	W of Blooming Prairie	Steele		0110	8miles	One house was flattened and numerous others were damaged. Trees were also debarked. Debris also flew into a mobile home where one person was injured.
EF2	N of Blooming Prairie (1st tornado)	Steele, Dodge		0121	6miles	A manufactured home was destroyed, injuring a resident. Sheds, outbuildings and grain bins were also destroyed. It crossed paths with the 0110 UTC tornado.
EF0	N of Blooming Prairie (2nd tornado)	Steele, Dodge		0122	6miles	A shed was destroyed and numerous trees were damaged.
EF2	NE of Rush City	Chisago, Pine, Burnett (WI)		0144	8miles	A mobile home was destroyed and several houses were damaged. Extensive tree damage along the path. Two people were injured.
EF1	Rochester	Olmsted		0203	1.5miles	Major damage in the north side of town with 75 homes damaged and ten severely damaged or destroyed. Other buildings including a Menards store and other businesses around it were damaged. Several trees were blown down.
Iowa
EF0	NE of Lakota	Kossuth		2216	1miles	Tornado remained over open country.
EF0	NE of Ledyard	Kossuth		2224	1miles	Tornado spotted along Highway 169. No damage was reported.
EF0	E of Rake	Winnebago		2305	2miles	Tornado spotted by fire department with no damage.
Wisconsin
EF0	N of Grantsburg	Burnett		0205	unknown	A few trees were snapped.
EF1	W of Cream	Buffalo		0257	2miles	A few buildings were damaged and many trees were sheared or uprooted.
Sources: SPC Storm Reports for 06/17/10, NWS Twin Cities, NWS Twin Cities – Final list, NWS Duluth, NWS Grand Forks, NWS La Crosse, NCDC Storm Data

June 18 event

List of reported tornadoes – Friday, June 18, 2010
EF#	Location	County	Coord.	Time (UTC)	Path length	Comments/Damage
Iowa
EF0	NNE of St. Charles	Madison		2155	1miles	Brief tornado touchdown over an open field.^[21]
Sources: SPC Storm Reports for 06/18/10

Wadena supercell

Wadena supercell
Tornadoes:	3
Fujitascale:	EF4
Tornado Duration:	48 minutes
Fatalities:	20 injuries
Damages:	$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 4:48 pm CDT (2248 UTC) roughly 12miles south of Bluffton.^[19] 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 1.5miles, uprooting small trees and snapping limbs of larger ones.^[22] At 4:56 pm CDT (2256 UTC), a tornado warning was issued for portions of Becker, Clearwater, Hubbard, Otter Tail and Wadena Counties.^[23] Only two minutes after the warning was issued, a new tornado touched down about 3miles southwest of the city of Wadena.^[19] Within three minutes of forming, the multiple vortex tornado rapidly intensified, reaching EF4 intensity with winds estimated at 170mph. Before crossing the Otter Tail-Wadena County border, the storm's width had reached 1.1miles.^[24] 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 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.^{[25] [26]} 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.^[23] Continuing northeastward, the tornado gradually weakened before dissipating at 5:16 pm CDT (2316 UTC), ending its 10miles track.^[26] Around 5:30 pm CDT (2230 UTC), a third tornado, rated EF0, touched down within the supercell, this time roughly 1.5miles south-southwest of Nimrod. Over the following 18 minutes, this storm made several touchdowns along a 14.8miles track that continued into Cass County.^[19] Damage from this tornado was largely limited to broken tree limbs.^[27] Continuing northeast, the supercell eventually dissipated over Cass County around 6:30 pm CDT (2330 UTC).^[19]

Canadian Prairies flooding

North of the tornadic supercells, heavy rain affected areas of the southern Canadian Prairies where at least 4to of rain fell across southern Alberta and Saskatchewan on June 16 – 17 causing widespread flooding. A state of emergency was declared at the Blood Tribe Indian Reserve where people were stranded in homes due to flood waters.^[28] Nine municipal governments in Alberta also declared state of emergencies due to the flooding as did some areas of southern Saskatchewan. Portions of the Trans-Canada Highway were closed for 3km (02miles) due to flooding along the border between Saskatchewan and Alberta on June 18 and remained shut down until June 26. At times, 30000to of land around the highway was submerged by flood waters. Other roads and bridges were flooded and in some cases washed away. The Cypress Hills Interprovincial Park was also left inaccessible.^[29] In and around Medicine Hat, Alberta, most residents were forced to evacuate as water reached depths of 2feet. Agricultural areas sustained considerable losses throughout the region as entire harvests were lost to the floods and much of the growing season had past leaving no time to re-plant crops.^[30] Throughout Alberta, losses reached C$69 million ($70.3 million), including C$54 million ($55 million) in Medicine Hat alone. A total of 340 homes were affected by the floods, 11 of which had to be condemned. Additionally, 490feet of the Trans-Canada Highway had been washed out.^[31]

Due to the prolonged shut down of the Trans-Canada Highway, many businesses along the road experienced hundreds of thousands of dollars in lost profits. Some stores reported a 95 percent decrease in income, roughly C$4,000 daily.^[32] On June 25, some residents in Medicine Hat were given C$3,000 in aid from the Provincial Disaster Assistance Program. In the weeks after the disaster, reconstruction of roadways and bridges washed out by the floods began. Engineers estimated that it would take four to five weeks to repair the Trans-Canada Highway.^[31]

June 18 Midwest derechos

Following the prolific tornado outbreak, a mesoscale convective system developed across eastern Nebraska in the Omaha area during the morning hours of June 18. It gradually intensified before moving into the Des Moines area near midday.^[33] The bow echo intensified into an intense progressive derecho over eastern Iowa and propagated eastward into northern Illinois and southern Wisconsin that afternoon. Extensive damage was reported from the derecho, including in the Chicago metropolitan area as the derecho reached that region shortly before 4:00 pm CDT (2100 UTC).^[34] Nearly 300,000 customers lost power and windows were blown out of high-rise buildings in downtown Chicago.^[35] Some counties utilized warning sirens due to the derecho's extreme winds, despite the fact that there was no formal tornado warning.^[36]

The derecho continued eastward, maintaining its strength over southern Lower Michigan and northern Indiana in the early evening hours. Winds as high as 90mph were reported in southwest Michigan with widespread damage over the region).^[34] The storm knocked out power to nearly 300,000 customers of Commonwealth Edison in the Chicago area. Windows were blown out of several high rises in downtown Chicago, including the tallest building, the Willis Tower. ^[37] More than 100,000 lost power in the immediate Detroit region including in Oakland and Wayne Counties,^[38] over 75,000 in the Grand Rapids/Kalamazoo regions ^[39] and over 50,000 in northern Indiana and southwestern Michigan.^[40] The derecho finally weakened and rapidly dissipated as it reached Lake Erie.

During the evening hours of June 18, a second, weaker derecho formed over Iowa and began following a path similar to the first one, and by 8:45 pm CDT (0145 UTC) the storm was moving across Illinois causing damage in areas already affected by the initial derecho event before weakening and dissipating. One fatality was reported from the event in northern Indiana and in Dexter, Michigan. This storm also produced dangerous lightning with two homes hit by lightning in Dexter and Scio Township in Michigan.

See also

• Weather of 2010
• List of North American tornadoes and tornado outbreaks
• List of F4 and EF4 tornadoes
  • List of F4 and EF4 tornadoes (2010–2019)

Notes and References

1. Web site: Reference at www.crh.noaa.gov.
2. Web site: John Chris Broyles and Jonathan M. Garner. Storm Prediction Center. National Oceanic and Atmospheric Administration. June 16, 2010. June 19, 2011. Jun 16, 2010 0600 UTC Day 1 Convective Outlook.
3. Web site: Storm Prediction Center Jun 17, 2010 0600 UTC Day 1 Convective Outlook.
4. Web site: Storm Prediction Center Severe Thunderstorm Watch 333.
5. Web site: 404 Not Found kare11.com.
6. Web site: 404 Not Found kare11.com.
7. Web site: Reference at www.kttc.com.
8. Web site: Reference at www.crh.noaa.gov.
9. Web site: SPC Day 1 Outlook.
10. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF0 Tornado.
11. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF0 Tornado.
12. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF1 Tornado.
13. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF2 Tornado.
14. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF0 Tornado.
15. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF0 Tornado.
16. Web site: National Climatic Data Center. 2011. June 19, 2011. South Dakota Event Report: EF2 Tornado.
17. Web site: National Climatic Data Center. 2011. June 20, 2011. Montana Event Report: EF1 Tornado.
18. Web site: National Climatic Data Center. 2011. June 19, 2011. North Dakota Event Report: EF1 Tornado.
19. Web site: National Weather Service office in Duluth, Minnesota. National Oceanic and Atmospheric Administration. June 18, 2011. June 19, 2011. Tornadoes: June 17, 2010 Tornado Outbreak Summary.
20. Web site: National Climatic Data Center. 2011. June 19, 2011. North Dakota Event Report: EF0 Tornado.
21. Web site: National Climatic Data Center. 2011. June 19, 2011. Iowa Event Report: EF0 Tornado.
22. Web site: National Climatic Data Center. 2011. June 19, 2011. Minnesota Event Report: EF1 Tornado.
23. Web site: Severe Weather Statement: Tornado Warning. June 17, 2010. June 19, 2011. National Weather Service Office in Grand Forks, North Dakota. Iowa Environmental Mesonet National Weather Service.
24. Web site: National Climatic Data Center. 2011. June 19, 2011. Minnesota Event Report: EF4 Tornado.
25. Web site: Associated Press. Minnesota Public Radio. July 9, 2010. June 19, 2011. $35.5M in public damage from Minn. June tornadoes.
26. Web site: National Climatic Data Center. 2011. June 19, 2011. Minnesota Event Report: EF4 Tornado.
27. Web site: National Climatic Data Center. 2011. June 19, 2011. Minnesota Event Report: EF0 Tornado.
28. Web site: Andree Lau. CBC News. Rain saturates southern Alberta. June 17, 2010. June 17, 2010.
29. Web site: Unattributed. CBC News. June 18, 2010. June 19, 2011. Floods close Trans-Canada at Sask.-Alta. border.
30. Web site: Unattributed. CTV Edmonton. June 21, 2010. June 19, 2011. Flood damage 'extensive' in southern Saskatchewan.
31. Web site: Joe Fries. Calgary Herald. Postmark News. June 25, 2010. June 19, 2011. Alberta flood tab set at $66 million.
32. Web site: Katie Schneider. Calgary Sun. June 26, 2010. June 19, 2011. Business dries up after flood.
33. Web site: Storm Prediction Center Mesoscale Discussion 1005.
34. Web site: 20100618's Storm Report (1200 UTC − 1159 UTC). SPC Storm Reports. Noaa.gov. 18 June 2010.
35. Web site: At least 284,000 without power from storms - KWQC-TV6 News and Weather for the Quad Cities - . 2010-06-18 . dead . https://web.archive.org/web/20100621034027/http://www.kwqc.com/Global/story.asp?S=12675100 . 2010-06-21 .
36. News: Storm Sirens Now Sound When Winds Hit 70MPH . 19 June 2010 . KCVI-News . 18 June 2010 . dead . https://web.archive.org/web/20120307190943/http://www.kcci.com/news/23956776/detail.html . 7 March 2012 .
37. Web site: Thunderstorms, Winds Leave Damage Across Area - cbs2chicago.com . 2010-06-19 . dead . https://web.archive.org/web/20100621234547/http://cbs2chicago.com/local/severe.thunderstorms.friday.2.1759745.html . 2010-06-21 .
38. Web site: Reference at www.wxyz.com.
39. Web site: About 1,000 remain without power | WOOD TV8 . 2010-06-19 . dead . https://web.archive.org/web/20100622041842/http://www.woodtv.com/dpp/news/local/kalamazoo_and_battle_creek/Storms-knock-out-power-in-Kzoo . 2010-06-22 .
40. Web site: Trees down, power out after Friday evening's storm. https://web.archive.org/web/20100621032040/http://www.wndu.com/hometop/headlines/96697759.html. 2010-06-21.