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<br />RISK AND VULNERABILITY ASSESSMENT <br />Ramsey County Multijurisdictional Hazard Mitigation Plan | July 2012 4-9 <br />Land Use and Development Trends <br />Ramsey County currently has no land use or development trends related to severe winter storms. <br />Hazard Summary <br />Severe winter storms, unlike other natural hazards, typically afford communities some advance warning. <br />The NWS issues winter storm watches, warnings, and advisories as these storms make their way through <br />the County. Due to the frequency of winter storms in Ramsey County, most buildings and infrastructure <br />are typically designed to sustain severe winter conditions. However, aging facilities and particularly <br />heavy snowfalls bring the possibility of building collapse and infrastructure damage. Additionally, while <br />many motorists are accustomed to driving in snow and icy conditions, winter weather always brings a <br />possibility for dangerous driving conditions and therefore should be a consideration in hazard mitigation <br />planning. It is also important to note that the County has never received an emergency declaration (local <br />or presidential) due to a winter storm event. <br />4.3.1.2 Severe Thunderstorms <br />Hazard Identification <br />Ramsey County used data from the NCDC, the NWS, and Ramsey County Emergency Operations Plan in <br />researching severe thunderstorms and their impact on Ramsey County. Severe thunderstorms include <br />thunderstorms and winds associated with the thunderstorms. Thunderstorm winds are generally short in <br />duration, involving straight-line winds and/or gusts in excess of 50 mph. Thunderstorm winds tend to <br />affect areas of the County with significant tree stands as well as areas with exposed property and <br />infrastructure and aboveground utilities. Thunderstorm winds can cause power outages, transportation and <br />economic disruptions, and significant property damage, and pose a high risk for injuries and loss of life. <br />Hazard Profile <br />The most prevalent natural hazard event occurring in Ramsey County is severe thunderstorms and the <br />winds from these thunderstorms. During the spring and summer months, the County typically experiences <br />multiple thunderstorms, some with significant winds. Over the past 20 years, 100 severe summer <br />thunderstorm wind events have been recorded within Ramsey County. A review of historical weather data <br />indicates there is a very significant chance of severe summer thunderstorm winds impacting Ramsey <br />County each year. Severe summer thunderstorm winds occur more frequently than any other natural <br />hazard event within Ramsey County. The most damaging severe thunderstorm/high winds occurred on <br />September 21, 2005, when high winds caused damage costing $25 million statewide. <br />Assets Exposed to Hazard <br /> Property Risk/Vulnerability: In evaluating assets that are susceptible to severe thunderstorms, it <br />was determined that all critical facilities as well as all public, private, and commercial property is <br />susceptible to severe thunderstorms. <br /> People Risk/Vulnerability: In evaluating vulnerability of the population in Ramsey County, it was <br />determined that risk/vulnerability includes the entire population of the County since there is no way <br />to determine the impact/magnitude of a severe summer thunderstorm and no way to predict where a <br />storm will hit. People are vulnerable to severe summer thunderstorms through power outages, effects <br />on transportation routes, establishment of shelters, roofs blown off structures, etc. This is particularly <br />true for severe summer thunderstorms, since they occur frequently within the County. Furthermore, <br />high winds associated with severe thunderstorms can take down power and cable lines, cutting <br />residents’ links to public information and other critical information.