Tornado outbreak of August 6, 1969

On August 6, 1969, a destructive tornado outbreak affected portions of north central Minnesota on August 6, 1969. The severe weather event generated 13 confirmed tornadoes, killed 15 people, and caused 109 injuries. To date, the outbreak remains the deadliest on record in the North Woods region of Minnesota. It is also known as the 1969 Minnesota tornado outbreak and the 1969 North Woods tornado outbreak. The most destructive tornado of the outbreak was a 32-mile-long (51 km) violent F4 that leveled miles of timberland and farmland across portions of Crow Wing, Cass, and Aitkin counties in Minnesota, killing at least 12 people and injuring 70 others.[3][4][nb 2][nb 3][nb 4]

Tornado outbreak of August 6, 1969
Splintered debris with trees leaning in the background
Damage to cabins near the current Lake Roosevelt Resort just north of Outing, Minnesota
TypeTornado outbreak
DurationAugust 6, 1969
Highest gust60 kn (69 mph; 110 km/h) in Iowa[1]
Tornadoes
confirmed		13
Max. rating1F4 tornado
Duration of
tornado outbreak2		7 hours, 25 minutes
Largest hail1 in (2.5 cm) in Clearwater County, Minnesota[2]
Fatalities15 fatalities, 109 injuries
Damage~$4.27 million (1969 USD)
~$34.1 million (2023 USD)[nb 1]
Areas affectedMinnesota, Nebraska

1Most severe tornado damage; see Fujita scale
2Time from first tornado to last tornado

Background
An F4 tornado caused major damage to many cabins and wide swaths of forest on both sides of Lake Roosevelt in the Outing, Minnesota, area.

Very warm, humid, summertime air had pushed into central and southern Minnesota on August 6, 1969. Minneapolis recorded a high temperature of 93 °F (34 °C) with dew points near 70 °F (21 °C). Meanwhile, strong upper-level winds over northern Minnesota and an approaching cold front from the west added the needed ingredient for the strong storms.[3] Two distinct thunderstorms formed approximately 45 mi (72 km) apart and tracked east-northeastward across Minnesota at 50 mph (80 km/h).[14] These parallel storms generated 13 tornadoes, killing fifteen people and injuring 109.

The first tornado of the day, rated F0, touched down at 1:15 p.m. CDT (12:15 p.m. CST; 18:15 UTC) in Beltrami County.[3][15] The main tornado event started about three hours later in Cass County when an F3 tornado touched down southwest of Backus, injuring four people.[16] The most damaging tornado of the outbreak touched down at 4:48 p.m. CDT (3:48 p.m. CST; 21:48 UTC) in Crow Wing County. It achieved F4 strength, traveling 32 miles (51 km) through Crow Wing, Cass and Aitkin counties. The area around Outing was especially hard hit by this tornado, where eleven deaths and forty injuries occurred on the shores of Roosevelt Lake.[3]

Several more strong tornadoes touched down over the next two hours, killing one person near Jacobson and two people near Two Harbors.[3] Damage and casualties were limited, however, because most of the twisters struck rural areas.

Confirmed tornadoes
Confirmed tornadoes by Fujita rating
FU F0 F1 F2 F3 F4 F5 Total
0* 1 0 3 8 1 0 13
"FU" denotes unclassified but confirmed tornadoes.
Confirmed tornadoes – Wednesday, August 6, 1969[nb 5][nb 6]
F# Location County / Parish State Start
coord.		 Time (UTC) Path length Max. width Summary
F0 Bemidji area Beltrami MN 47.50°N 94.85°W / 47.50; -94.85 (Bemidji (August 6, F0)) 18:15–? 0.1 miles (0.16 km) 33 yards (30 m) A short-lived waterspout affected Lake Bemidji.[18]
F3 NE of Nimrod to ENE of Backus Cass MN 46.72°N 94.73°W / 46.72; -94.73 (Backus (August 6, F3)) 21:20–21:40 17.3 miles (27.8 km) 167 yards (153 m) This strong tornado first touched down northeast of Nimrod and lifted at the southeastern corner of Big Portage Lake.[16] The tornado significantly damaged or destroyed 13 farms to the southeast of Backus.[19] Additionally, it destroyed 11 homes to the east of Backus.[18] One trailer was destroyed as well.[19] Four people were seriously injured and hospitalized, and damages totalled $850,000.[18]
F4 NW of Swanburg to SE of Hill City Crow Wing, Cass, Aitkin MN 46.78°N 94.22°W / 46.78; -94.22 (Outing (August 6, F4)) 21:48–22:28 32.3 miles (52.0 km) 833 yards (762 m) 12 deaths – This large, violent tornado attained a width of almost 1 mi (2 km; 1,760 yd; 1,609 m) while passing through Outing.[20] The area around Lake Roosevelt saw 11 of the 12 deaths as well as about 40 children sustaining injuries while vacationing.[19] Along its path, the tornado hurled cars and downed thousands of trees, many of which were debarked. The tornado also destroyed scores of cabins and leveled farms.[19] In all, 70 people were injured, and losses reached $2.15 million.[20] The death toll may have exceeded 12.[19]
F3 NNE of Chisholm to S of Idington St. Louis MN 47.60°N 92.83°W / 47.60; -92.83 (Chisholm (August 6, F3)) 22:25–22:38 10 miles (16 km) 300 yards (270 m) This tornado reportedly exceeded 2 mi (3 km; 3,520 yd; 3,219 m) in width.[14] It destroyed numerous trees, homes, and cabins. Nine people were injured, and losses reached $675,000.[19] The tornado ended just north of Big Sandy Lake.[20] In his reanalysis, researcher Thomas P. Grazulis listed the tornado as an F2.[19]
F3 SE of Hill City to ESE of Ball Bluff Aitkin MN 46.90°N 93.45°W / 46.90; -93.45 (Jacobson (August 6, F3)) 22:50–23:03 12.5 miles (20.1 km) 1,500 yards (1,400 m) 1 death – This tornado formed from the same storm as the previous tornado, and passed near Jacobson. It destroyed two homes and seven outbuildings on farms, and killed one person in a small cabin.[20][19] Losses reached $250,000. The number of injuries was unknown at the time, but was later listed as three in official records.[20][19][21] Grazulis listed this tornado as an F2.[19]
F2 SSE of Wahlsten St. Louis MN 47.73°N 92.28°W / 47.73; -92.28 (Wahlsten (August 6, F2)) 23:00–? 0.1 miles (0.16 km) 150 yards (140 m) This tornado and the following two events occurred in close proximity and succession. The first of the three tornadoes produced losses of $20,000.[20] Grazulis did not list this tornado as F2 or stronger.[22]
F2 S of Tower St. Louis MN 47.77°N 92.27°W / 47.77; -92.27 (Tower (August 6, F2)) 23:00–? 0.1 miles (0.16 km) 150 yards (140 m) Losses totaled $19,000.[20] Grazulis did not list this tornado as F2 or stronger.[22]
F3 SW of Tower to SSW of Eagles Nest St. Louis MN 47.80°N 92.28°W / 47.80; -92.28 (Eagles Nest (August 6, F3)) 23:00–? 7.2 miles (11.6 km) 220 yards (200 m) This strong tornado damaged or destroyed several homes and barns, while downing hundreds of trees. Its total path length may have been 9 mi (14 km) and ended near the southwestern corner of Eagles Nest Lake Three.[23] Total losses reached $110,000, and the path width reached 1⁄2 mi (1 km; 880 yd; 805 m).[20] Grazulis listed this event as an F2.[23]
F3 WNW of Floodwood to NNE of Prosit St. Louis MN 46.95°N 92.98°W / 46.95; -92.98 (Floodwood (August 6, F3)) 23:00–23:29 18.4 miles (29.6 km) 2,933 yards (2,682 m) According to the National Weather Service, damage from this tornado was nearly as intense as that of the Outing F4, spawned by the same thunderstorm.[3] This tornado was up to 2.5 mi (4 km; 4,400 yd; 4,023 m) wide near Floodwood.[20] It killed 39 head of cattle, felled hundreds of trees, and destroyed several cabins and barns. Total losses reached $845,000, and 20 people were injured.[23]
F3 SW of Eagles Nest to SSE of McComber St. Louis MN 47.82°N 92.13°W / 47.82; -92.13 (McComber (August 6, F3)) 23:15–? 3.8 miles (6.1 km) 250 yards (230 m) This tornado destroyed trees and cottages in its path, resulting in losses of $60,000. The tornado may have tracked for 5 mi (8 km), and was listed as an F2 by Grazulis.[23]
F2 S of Burntside to S of Ely St. Louis MN 47.87°N 91.93°W / 47.87; -91.93 (Burntside (August 6, F2)) 23:35–? 1.9 miles (3.1 km) 193 yards (176 m) Losses reached $8,000.[20] Grazulis did not list this tornado as F2 or stronger.[22]
F3 NNE of Fredenberg to WNW of Two Harbors St. Louis, Lake MN 47.05°N 92.15°W / 47.05; -92.15 (Two Harbors (August 6, F3)) 23:50–00:15 17.2 miles (27.7 km) 117 yards (107 m) 2 deaths – On the eastern shoreline of Boulder Lake, a cabin was destroyed, resulting in two fatalities.[20][23] Hundreds of trees were splintered and three people were injured. The tornado exhibited a skipping path, with losses of $123,000.[23][20]
F0 ENE of Monroe Platte NE 41.48°N 97.58°W / 41.48; -97.58 (Monroe (August 6, F0)) 01:40–? Un­known Un­known A brief touchdown occurred over uninhabited countryside.[24]

See also

Notes
  1. All losses are in 1969 USD unless otherwise noted.
  2. An outbreak is generally defined as a group of at least six tornadoes (the number sometimes varies slightly according to local climatology) with no more than a six-hour gap between individual tornadoes. An outbreak sequence, prior to (after) the start of modern records in 1950, is defined as a period of no more than two (one) consecutive days without at least one significant (F2 or stronger) tornado.[5]
  3. The Fujita scale was devised under the aegis of scientist T. Theodore Fujita in the early 1970s. Prior to the advent of the scale in 1971, tornadoes in the United States were officially unrated.[6][7] While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007,[8] Canada utilized the old scale until April 1, 2013;[9] nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale.[10]
  4. Historically, the number of tornadoes globally and in the United States was and is likely underrepresented: research by Grazulis on annual tornado activity suggests that, as of 2001, only 53% of yearly U.S. tornadoes were officially recorded. Documentation of tornadoes outside the United States was historically less exhaustive, owing to the lack of monitors in many nations and, in some cases, to internal political controls on public information.[11] Most countries only recorded tornadoes that produced severe damage or loss of life.[12] Significant low biases in U.S. tornado counts likely occurred through the early 1990s, when advanced NEXRAD was first installed and the National Weather Service began comprehensively verifying tornado occurrences.[13]
  5. All dates are based on the local time zone where the tornado touched down; however, all times are in Coordinated Universal Time and dates are split at midnight CST/CDT for consistency.
  6. Prior to 1994, only the average widths of tornado paths were officially listed.[17]

References
  1. National Weather Service (May 2019). Events reported between 08/06/1969 and 08/06/1969 (1 day) (Report). National Centers for Environmental Information. Retrieved November 18, 2019.
  2. National Weather Service (May 2019). Events reported between 08/06/1969 and 08/06/1969 (1 day) (Report). National Centers for Environmental Information. Retrieved November 18, 2019.
  3. "Northwoods Tornado Outbreak August 6, 1969". NWS Weather Forecast Office Duluth, MN. Duluth, Minnesota: National Weather Service. 2019. Archived from the original on August 6, 2019. Retrieved September 11, 2019.
  4. Haskins, Austin (August 6, 2019). "Tuesday marks 50th anniversary of deadliest tornado outbreak in northern Minnesota". KBJR6.com. Duluth, Minnesota: KBJR-TV. Archived from the original on August 6, 2019. Retrieved September 17, 2019.
  5. Schneider, Russell S.; Brooks, Harold E.; Schaefer, Joseph T. (2004). Tornado Outbreak Day Sequences: Historic Events and Climatology (1875-2003) (PDF). 22nd Conf. Severe Local Storms. Hyannis, Massachusetts: American Meteorological Society. Retrieved September 17, 2019.
  6. Grazulis 1993, p. 141.
  7. Grazulis 2001a, p. 131.
  8. Edwards, Roger (March 5, 2015). "Enhanced F Scale for Tornado Damage". The Online Tornado FAQ (by Roger Edwards, SPC). Storm Prediction Center. Retrieved February 25, 2016.
  9. "Enhanced Fujita Scale (EF-Scale)". Environment and Climate Change Canada. June 6, 2013. Archived from the original on March 3, 2016. Retrieved February 25, 2016.
  10. "The International Tornado Intensity Scale". Tornado and Storm Research Organisation. 2016. Archived from the original on March 5, 2016. Retrieved February 25, 2016.
  11. Grazulis 2001a, pp. 251–4.
  12. Edwards, Roger (March 5, 2015). "The Online Tornado FAQ (by Roger Edwards, SPC)". Storm Prediction Center: Frequently Asked Questions about Tornadoes. Storm Prediction Center. Retrieved February 25, 2016.
  13. Cook, A. R.; Schaefer, J. T. (August 2008). Written at Norman, Oklahoma. "The Relation of El Niño–Southern Oscillation (ENSO) to Winter Tornado Outbreaks". Monthly Weather Review. Boston: American Meteorological Society. 136 (8): 3135. Bibcode:2008MWRv..136.3121C. doi:10.1175/2007MWR2171.1. open access
  14. Kuehnast, Earl L. (August 1969). "The Different Behavior Patterns of Twelve Tornadoes Occurring August 6, 1969". Special Weather Summary. Climatological Data. Minnesota. Asheville, North Carolina: National Climatic Data Center. 75 (8): 128.
  15. National Weather Service (May 2019). Minnesota Event Report: F0 Tornado (Report). National Centers for Environmental Information. Retrieved September 11, 2019.
  16. National Weather Service (May 2019). Minnesota Event Report: F3 Tornado (Report). National Centers for Environmental Information. Retrieved September 11, 2019.
  17. Brooks, Harold E. (April 2004). "On the Relationship of Tornado Path Length and Width to Intensity". Weather and Forecasting. Boston: American Meteorological Society. 19 (2): 310. Bibcode:2004WtFor..19..310B. doi:10.1175/1520-0434(2004)019<0310:OTROTP>2.0.CO;2.
  18. U.S. Weather Bureau (August 1969). "Storm Data and Unusual Weather Phenomena". Storm Data. Asheville, North Carolina: National Climatic Data Center. 11 (8): 121.
  19. Grazulis 1993, p. 1106
  20. USWB 1969, p. 122
  21. National Weather Service (May 2019). Minnesota Event Report: F3 Tornado (Report). National Centers for Environmental Information. Retrieved September 11, 2019.
  22. Grazulis, Thomas P. (July 1993). Significant Tornadoes 1680–1991: A Chronology and Analysis of Events. St. Johnsbury, Vermont: The Tornado Project of Environmental Films. pp. 1106–7. ISBN 1-879362-03-1.
  23. Grazulis 1993, p. 1107
  24. USWB 1969, p. 123
  25. Kuehnast 1969, p. 129
  26. National Weather Service (May 2019). Events reported between 08/06/1969 and 08/07/1969 (2 days) (Report). National Centers for Environmental Information. Retrieved September 9, 2019.

Sources
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