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Anoka County Multi- Jurisdictional All Hazards Mitigation Plan While higher population and housing densities in the municipalities set the stage for increased impact, the potential for property damage and loss of live is equally high for the unincorporated areas of the county due to the large number of mobile homes throughout the rural areas. A detailed list of Tornado incidents is in Appendix A. 4.3.1.11 Severe Weather — Winter Storms Winter storms include heavy snow, blizzards and extreme cold. Winter storms in Minnesota often include extreme cold and ice. These storms are especially hazardous in terms of closing emergency routes, creating power and utility system failures, and immobilizing economic activity. In Minnesota, a heavy snow event is defined by six or more inches of snow in a 12 -hour period and eight or more inches of snow in a 24 -hour period. Snow is considered heavy when visibilities drop below one - quarter mile regardless of wind speed. Blizzards are the most violent of the winter storms and are characterized by low temperatures, usually below 20o Fahrenheit, accompanied by strong winds in excess of 35 miles per hour with enough snow in the air caused by either falling or blowing snow to create visibilities of one - quarter mile or less for an extended period of time, usually at least three hours or more. While blizzards can occur in Anoka County from October through April, they most commonly occur from November through the end of March. Ice storms bring the entire affected area to a standstill. Ice accumulation causes trees and utility lines to fall, interrupting telephone service and creating significant power outages. Emergency response time is greatly increased, especially to residents in remote, rural areas. Freezing rain, probably the most serious of the ice storms, occurs during a precipitation event when warm air aloft exceeds 32o while the surface remains below the freezing point. When precipitation originating as rain or drizzle contacts physical structures on the surface ice forms on all surfaces creating problems for traffic, utility lines and tree limbs. Recent Winter Storms impacted the city of Blaine in 1991, 1996 and 2001. The 1991 & 2001 storms were heavy snowfall events, which impacted transportation, commerce and emergency services. The 1996 events was an ice storm, which resulted in over 35 motor vehicle accidents, 7 injuries and numerous reports of trees and power lines down. Due to climate and geographic location winter storms can be a frequent occurrence for the City of Blaine. With Blaine's rate of growth and construction practices Toss impact from future Winter storms would be more significant than what has been seen historically. • Columbia Heights experiences severe Winter Storms frequently, usually resulting in downed power lines and downed trees. The resulting impact is power outages to residents and