Tornado outbreak of August 6, 1969

On August 6, 1969, a destructive tornado outbreak affected portions of the Upper Midwest—principally north-central Minnesota—on August 6, 1969. The severe weather event generated 14 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 33 mi 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.

Background
Very warm, humid, summertime air had pushed into central and southern Minnesota on August 6, 1969. Minneapolis recorded a high temperature of 93 F with dew points near 70 F. Meanwhile, strong upper-level winds over northern Minnesota and an approaching cold front from the west added the needed ingredient for the strong storms. Two distinct thunderstorms formed approximately 45 mi apart and tracked east-northeastward across Minnesota at 50 mi/h. These parallel storms generated 14 tornadoes, killing 15 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. The main tornado event started about three hours later in Cass County when an F3 tornado touched down southwest of Backus, injuring four people. 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 33 mi through Crow Wing, Cass and Aitkin counties. The area around Outing was especially hard hit by this tornado, where 11 deaths and 40 injuries occurred on the shores of Roosevelt Lake.

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

Confirmed tornadoes
{{efn|Prior to 1990, there is a likely undercount of tornadoes, particularly E/F0–1, with reports of weaker tornadoes becoming more common as population increased. A sharp increase in the annual average E/F0–1 count by approximately 200 tornadoes was noted upon the implementation of NEXRAD Doppler weather radar in 1990–1991.{{sfn|Agee and Childs|2014|p=1496}}{{efn|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.{{sfn|Grazulis|2001a|pp=251–4}} Most countries only recorded tornadoes that produced severe damage or loss of life. 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.{{sfn|Cook|Schaefer|2008|p=3135}}|group=note|name=Count}} 1974 marked the first year where significant tornado (E/F2+) counts became homogenous with contemporary values, attributed to the consistent implementation of Fujita scale assessments.{{sfn|Agee and Childs|2014|pp=1497, 1503}}{{efn|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.{{sfn|Grazulis|1993|p=141}}{{sfn|Grazulis|2001a|p=131}} Tornado ratings were retroactively applied to events prior to the formal adoption of the F-scale by the National Weather Service.{{sfn|Edwards et al.|2013|p=641–642}} While the Fujita scale has been superseded by the Enhanced Fujita scale in the U.S. since February 1, 2007, Canada used the old scale until April 1, 2013; nations elsewhere, like the United Kingdom, apply other classifications such as the TORRO scale. |group=note|name=Fujita}} Numerous discrepancies on the details of tornadoes in this outbreak exist between sources. The total count of tornadoes and ratings differs from various agencies accordingly. The list below documents information from the most contemporary official sources alongside assessments from tornado historian Thomas P. Grazulis.