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<br />RISK AND VULNERABILITY ASSESSMENT
<br />Ramsey County Multijurisdictional Hazard Mitigation Plan | July 2012 4-5
<br />4.3 Natural Hazards
<br />Natural hazards such as floods, tornadoes, winter storms, and the like are an enduring condition around
<br />the human environment. Natural hazards become disasters when they intersect with the human
<br />environment. This problem has been exacerbated due to the impacts of climate change. In Minnesota,
<br />natural disasters have had devastating effects on human lives, property, the economy, and the community.
<br />While most processes present little danger to human well-being, some develop into hazardous situations
<br />that place life, property, economy, and community at higher risk.
<br />4.3.1 Atmospheric Hazards
<br />Atmospheric hazards include weather-generated incidents. Each has its own natural characteristics,
<br />geographic location and/or aerial extent, seasonality, severity, and associated risks. Though these
<br />characteristics allow identification of each individual hazard, many of these hazards are interrelated
<br />(FEMA, 1997). For example, tornadoes can be a product of severe thunderstorms or tropical
<br />storms/hurricanes, and snow or ice can be a byproduct of nor’easters. These hazards may also be directly
<br />linked to other categories of natural hazards (for example, excessive rain can cause the geologic hazard of
<br />sinkholes and landslides). In addition, atmospheric hazards can be interlinked with technological hazards
<br />(for example, excessive rains can cause dam/levee failure, which can lead to flooding). These linkages
<br />make it difficult to attribute damage to one hazard or to assess the risk one hazard has on the planning
<br />area, but mitigation strategies quite often have beneficial effects on several types of hazards.
<br />In this subsection, six atmospheric hazards were addressed: severe winter storms, severe summer
<br />thunderstorms, tornadoes, lightning, extreme temperatures, and hailstorms. Each category has a general
<br />description of the hazard, a vulnerability summary for the planning area, and specific hazard information
<br />for each individual governing jurisdiction.
<br />4.3.1.1 Severe Winter Storms
<br />Hazard Identification
<br />Ramsey County researched historical data from the National Climatic Data Center (NCDC) and the
<br />National Weather Service (NWS) as well as information from past newspaper articles relating to severe
<br />winter storms in Ramsey County. Severe winter storms bring the threat of snow, freezing rain, and ice
<br />storms to the County. A heavy accumulation of ice, especially when accompanied by high winds,
<br />devastates trees and power lines. Sidewalks, streets, and highways become extremely hazardous to
<br />pedestrians and motorists. Severe winter storms originate as mid-latitude depressions of cyclonic weather
<br />systems and can cause snowstorms, blizzards, and ice storms. Winter storms can paralyze a
<br />county/community by shutting down normal day-to-day operations and can produce an accumulation of
<br />snow and ice on trees and utility lines, resulting in loss of electricity and blocked transportation routes.
<br />These storms can also lead to frozen water pipes, which when erupted, can lead to extensive property
<br />damage and the depletion of natural resources. When counties/communities have long-term loss of
<br />utilities, elderly and extremely young populations become more vulnerable to the effects of the extreme
<br />temperatures associated with these storms.
<br />Hazard Profile
<br />To determine Ramsey County’s vulnerability to severe winter storms, a time period from 1993 to 2010
<br />was examined. Numerous sources were used in identifying the severe winter storm hazards that have
<br />occurred in Ramsey County since 1993 (both primary and secondary). Sources included the Cable News
<br />Network, National Oceanic Atmospheric Agency (NOAA), National Climatic Data Center (NCDC), the
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