Agenda Packets - 2012/08/13 - Laserfiche WebLink

Home Browse Search

Section 4 4-16 Ramsey County Multijurisdictional Hazard Mitigation Plan | July 2012 Hazard Profile All of Ramsey County is vulnerable to the threat of a tornado because no one can predict exactly when or where a tornado might strike. Ramsey County has not experienced a tornado within the last 10 years. Although the County has not experienced a tornado in recent history, countless tornado watches have been recorded during this period. Additionally, surrounding counties have experienced tornadoes during this 10-year period. Trend analysis indicates that a tornado will touch down in Ramsey County every 10 years. This equates to a 10 percent chance of a tornado touching down in Ramsey County in any given year. Although the statistical average for the number of tornadoes in one year in the state of Minnesota is 24, there have been instances where many more were reported as a result of one day of large storms. In 2011, a particularly strong storm system moved through the state and produced 48 tornadoes in one day, increasing the overall number of tornadoes to 102 for the year. Tornadoes tend to strike in somewhat random fashion, making the task of reliably calculating a recurrence interval extremely difficult. The damage potential associated with a tornado is extremely high. Assets Exposed to Hazard  Property Risk/Vulnerability: It can be assumed that all structures and facilities within Ramsey County could be damaged by a tornado because tornadoes are among the most unpredictable of weather phenomena and are indiscriminate as to when or where they strike.  People Risk/Vulnerability: In evaluating vulnerability of the population in Ramsey County, it was determined that risk/vulnerability includes the entire population of the County since there is no way to determine the impact/magnitude of a tornado and no way to predict when or where a tornado will hit. People are vulnerable to the effects of tornadoes, including power and cable outages, disruption to transportation routes, damage to shelter, flying debris, etc. This is particularly true due to a 10 percent chance of a tornado occurring in any given year in the County.  Environment Risk/Vulnerability: Risks to the environment can be significant. Environmental risks can include flying debris and destruction of critical infrastructure that damage and affect water supply and contamination of potable water for public consumption. Estimate of Potential Losses An obstacle to accurate loss estimation is the fact that losses may vary widely even within one category of natural hazard, depending on place and location. For instance, a tornado may hop from one location to another in a primarily rural area of the County, creating virtually no economic damage, whereas a similar hazard incident in an urban area might create millions of dollars in damages. Compounding this obstacle to accurate loss estimation is that tornadoes range considerably in their intensity and duration. When estimating losses related to tornado events, it can be assumed that structures or facilities with the greatest replacement value will be those that sustain the most monetary damage. In addition, facilities with vulnerable populations include nursing homes and personal care homes as well as public and private schools located throughout the County. Land Use and Development Trends Ramsey County currently has no land use or development trends related specifically to tornadoes. The minimum standards established by these codes provide reasonable protection to persons and property within structures that comply with the regulations for most natural hazards.