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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />of the 1-94 exit at Highway 280. <br />The NWS estimates that 70% of winter storm related casualties result from vehicular accidents. <br />Heavy snow impedes traffic, creates hazardous travel conditions, and requires plowing and <br />surface treatment to keep roads passable. It also significantly reduces visibilities, which <br />compromises driver reaction times. In blizzard conditions, the effect of wind further restricts <br />visibilities, often to zero, and can easily disorient drivers. Stranded drivers and those forced to <br />leave their vehicles because of accidents are often directly exposed to the harsh conditions <br />outside their vehicles and can quickly find themselves in a life -threatening situation. <br />Airports frequently experience significant delays, and it is common for all runways to close for a <br />time during major winter storms. <br />4.3.11.4. Potential for cascading effects <br />Heavy snow and blizzard conditions can occupy a large portion of any strong, cold -season extratropical <br />cyclone, and as a result can precede, follow, or be accompanied by a wide range of weather conditions. <br />Situational awareness is key to understanding if and how the effects of winter storm conditions will be <br />compounded by the following hazards. <br />Flooding: Unusually intense and/or repetitive snowfalls can drain local governments of their <br />resources, as crews put in long hours to maintain roads, and clear debris. As the heavy snow melts, <br />it poses flooding risks for area streams, basements, low-lying intersections, and other areas prone <br />to ponding. Heavy rainfall events falling onto or just after the melting of a large snowpack pose <br />immediate flooding threats, as soil storage capacity is often very limited. In April of 2001, heavy <br />rains in southern Minnesota caused considerable flooding, after an unusually long and snowy <br />season left a large snowpack and saturated soils. <br />Extended power outages: A severe winter storm that knocks out power becomes much more <br />dangerous as the time to restore service increases. This is especially true of storms that are <br />followed by a rapid drop in temperatures. Residences and facilities dependent on electrical power <br />for heating or heat distribution can become dangerously cold within hours of power loss. <br />Sometimes a heavy snowfall event or blizzard occurs shortly after a major ice storm. In these <br />cases, the ice produces the initial critical loading, but then the snow and/or wind acts as the "final <br />straw," resulting in severe and widespread power outages. In these situations, the snowstorm or <br />blizzard is just another link in a chain of cascading hazards already in progress. <br />Overexertion: Snow removal after a major event often results in a casualty spike related to <br />overexertion resulting from attempting to dislodge stranded vehicles and clear snow from <br />sidewalks and driveways. It is a major cause of winter -related fatalities in the US. <br />Severe weather: In rare situations, a major winter storm can follow a significant severe weather <br />event. An infamous tornado -blizzard combination affected Janesville, WI on November 11, 1911. <br />The tornado killed nine people and was followed almost immediately by a historic cold front that <br />brought blizzard conditions within a couple hours of the tornado's passage, as temperatures fell <br />from the 60s and 70s into the teens. On April 26, 1984, a strong, killer tornado hit Minneapolis <br />and St. Anthony, and was followed within three days by up to 10 inches of snow. Most recently, <br />172 <br />