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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />The bow echo system began to produce significant wind damage over south-central Minnesota <br />about 10 p.m. Saturday evening. As the system moved rapidly eastward it grew south into <br />northern Iowa and caused damaging winds over most of southeast Minnesota and northeast <br />Iowa. Many trees and power lines were blown down and several farm buildings were damaged or <br />destroyed. <br />The most intense damage occurred near the northern end of the bow echo system in Minnesota, <br />from Sibley and McLeod Counties eastward across southern portions of the Minneapolis/St. Paul <br />metropolitan area. Along this band, winds greater than 80 mph were measured; in some areas, <br />estimated speeds reached 100 mph. Tens of thousands of trees were blown down, 500,000 <br />customers lost power, two semi -trailer trucks were overturned, two apartment building roofs <br />were blown off, and 100 boats were destroyed. In addition, over 100 homes were destroyed or <br />badly damaged, and over 2000 others received some damage. Twenty-two people were injured, <br />and damage to property was estimated to be about $48 million in 1998 U.S. dollars ... with $35 <br />million dollars of that damage occurring in Dakota County alone. <br />In summary, while crossing southern Minnesota and northeastern Iowa, the derecho event <br />caused about $50 million in 1998 U.S. dollars of damage, left about 600,000 customers without <br />power, and injured twenty-two people. In some areas, power was not restored until nearly a week <br />after the event. <br />Boundary Waters —Canadian Derecho <br />On July 4, 1991, a major derecho in <br />the BWCAW, known as the <br />®,10-33 % <br />Superior" National Forest <br />Boundary Waters -Canadian <br />034-66% <br />July 4, 1999, Storm Blow own <br />Derecho, lasted for more than 22 <br />6T-100% <br />' <br />hours traveled more than 1,300 <br />,w ,,. a �,..a�, ` ➢� � . �e�� � . <br />miles and produced wind speeds <br />averaging nearly 60 mph, peaking at <br />1 0 ,e <br />80-100 mph. The blowdown caused <br />p <br />widespread devastation with <br />casualties both in Canada and the <br />United States. The storm front <br />Figure 2. Percentage of trees blown down in Superior National <br />Forest in northeast Minnesota on July 4, 1999. Scale: 1 " =15 <br />initiated as large complex of <br />miles. (Courtesy of USDA Forest Service, Superior National <br />thunderstorms in South Dakota. The <br />Forest) <br />storm moved west to east snapping <br />tree trunks in half that pulled power lines <br />down with them in Cass, Crow Wing, Itasca and Aitkin <br />Counties. After blowing down trees on 1,300 acres on the Chippewa National Forest and dropping <br />heavy rains that eroded 9,000 acres of <br />shorelines, the storm continued into northeast Minnesota. <br />The storm entered the Arrowhead region of northeastern Minnesota in the early afternoon. Here, <br />winds of 80 to 100 mph resulted in injuries to about 60 canoe campers and damage to tens of <br />millions of trees within 477,000 acres of forest land on the Superior National Forest in the course <br />of leveling a swath 30 miles long and 4 to 12 miles wide. The storm affected approximately <br />477,000 acres (16 percent of the Superior National Forest). The BWCAW sustained the heaviest <br />damage in a line from Ely to the end of the Gunflint Trail. <br />.( <br />