08-12-2019 Council Packet - Laserfiche WebLink

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Anoka County 2019 Multi-Jurisdictional All Hazards Mitigation Plan 82 89B4.2.1.11 Severe Weather - Winter Storms Winter storms produce an array of hazardous weather conditions including heavy snow, blizzards, freezing rain, ice pellets, and extreme cold. The extreme cold associated with winter storms is a deceptive killer as it indirectly causes injury and death resulting from exhaustion and overexertion, asphyxiation, hypothermia, and frostbite from wind chill. Extreme ice and snow events are the most potentially disruptive to society, for they can bring down trees and power lines and lead to roof collapse. All forms of severe winter weather can make travel treacherous. Severe winter storms are extra-tropical cyclones (storms that form outside of the warm tropics) fueled by strong temperature gradients and an active upper-level jet stream. 90B4.2.1.12 Wildfires Wildfires are uncontrolled burning of grasslands, brush, or woodlands. According to FEMA, people start over four out of five forest fires. Negligent human behavior such as irresponsible smoking or not extinguishing campfires is the cause of many fires. The other primary causes of forest fires are lightning and arson. There are three different classes of wild-land fires. A surface fire is the most common type and burns along the floor of a forest, moving slowly and killing or damaging trees. A ground fire is usually started by lightning and burns on or below the forest floor. Crown fires spread rapidly by wind and move quickly by jumping along the tops of trees. Wild-land fires are usually signaled by dense smoke that fills the area for miles around. The potential for wildfire depends upon surface fuel characteristics, recent climate conditions, current meteorological conditions, and fire behavior. Hot, dry summers and dry vegetation increase susceptibility to fire in the fall, a particularly dangerous time of year for wildfire. Wild-land fires are wildfires in an area where development is essentially nonexistent except for roads, railroads, power-lines, and similar facilities. Urban wild-land interface fires are wildfires in a geographical area where structures and other human development meet or intermingle with wild-land or vegetative fuels.