August 6, 2009 marks the 40th anniversary of the deadliest tornado outbreak in the recorded history of northern Minnesota. As many as a dozen tornadoes formed over a period of nearly 6 hours. Fifteen people were killed and more than a hundred were injured.
Here is a map showing the specific tornado tracks and subsequent damage based on the Fujita Scale:
The first tornado was reported near Bemidji in Beltrami County at 1:15 pm (all times are central daylight). It was a weak F-0 tornado with a very short path and caused no damage.
The first damaging tornado touchdown occurred at 4:20 pm in Cass County, west of Pine River, and traveled northeast, destroying or causing severe damage to many homes and farms in the Backus area and injuring 4 people. This tornado was classified an F-3.
The first killer tornado (also the strongest, most damaging, and traveling the longest distance) was classified an F-4, and touched down near Stewart Lake in northwestern Crow Wing County at 4:48 pm. The tornado traveled northeast more than 30 miles across southeastern Cass County to just south of Hill City in Aitkin County. Eleven people died on the shore of Roosevelt Lake near Outing in Cass County and one person died at Reservoir Lake, between Outing and Hill City. Seventy people were injured, including 40 children staying at a camp on Roosevelt Lake. Thousands of trees and dozens of structures were destroyed, causing more than $2 million in damage.
Between 5 and 7 pm, as many as 9 more F-2 and F-3 tornadoes touched down near Chisholm, Jacobson, Tower-Soudan, Ely, Floodwood, and Two Harbors, killing 3 more people (1 near Jacobson and 2 near Two Harbors), injuring another 35, and causing millions of dollars in damage to buildings, utilities, and trees. In addition, 39 head of livestock were killed northeast of Floodwood.
The Weather Map
Very warm and humid air had pushed northward into southern and central Minnesota ahead of an occluded front that stretched from Lake Winnipeg in Canada to a low pressure area in north central South Dakota. Minneapolis saw a high temperature of 93º F with dew points around 70º F. Over the next 24 hours, the front would push rapidly east into the Upper Peninsula of Michigan. Along with strong upper level winds, all the ingredients for violent thunderstorms and tornadoes were present.
Click on images to enlarge
500 mb Analysis, 7 pm August 6, 1969 Surface Analysis, 5 pm August 6, 1969
Below are photos of the damage:
We are looking for personal stories from those who experienced the storms.
If you would like to share your story with us, contact Carol Christenson.
**Documentation of this event is preliminary and should not be considered official.
National Weather Service, Weather Forecast Office, Duluth, MN.
National Weather Service, Weather Forecast Office, Chanhassen, MN.
Wikipedia article: 1969 Minnesota tornado outbreak.
Grazulis, Thomas P., 1993: Significant Tornadoes 1680-1991. Pages 1106 - 1107. St. Johnsbury, VT: Environmental Films.
Daily Weather Maps for 4-10 August 1969, published by the U.S. Department of Commerce/Environmental Science Services Administration/Environmental Data Service.
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