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<br />RISK AND VULNERABILITY ASSESSMENT <br />Ramsey County Multijurisdictional Hazard Mitigation Plan | July 2012 4-17 <br />Vulnerability <br />Tornadoes <br />Frequency of Occurrence Likely <br />Warning Time Minimal <br />Geographic Extent Community-wide <br />Potential Impact Major <br />Multijurisdictional Concerns <br />All of Ramsey County has the same design wind speed of 200 mph, as determined by the American <br />Society of Civil Engineers (ASCE). As stated previously, the entire county can potentially be affected by <br />a tornado. As a result, any mitigation steps taken related to tornados should be undertaken on a <br />countywide basis. <br />Hazard Summary <br />Overall, Ramsey County has high exposure to potential damage from tornadoes. Should a tornado hit <br />certain portions of the County that are highly concentrated with homes or any of the critical facilities <br />identified, depending upon the strength and duration of the event, significant damage could occur. Due to <br />the destructive nature of tornadoes, it is imperative that pre-disaster mitigation measures be identified. <br />Table 4-3 15 <br />Confirmed Tornadoes <br />Location Date Type Mag Death Injuries Property <br />Damage <br />1 RAMSEY 5/6/1965 Tornado F4 0 108 25.0M <br />2 RAMSEY 6/28/1979 Tornado F1 0 0 250K <br />3 RAMSEY 6/14/1981 Tornado F3 1 60 25.0M <br />4 RAMSEY 4/26/1984 Tornado F3 0 0 25.0M <br />5 Roseville 5/15/1998 Tornado F1 0 0 150.0M <br />6 Mounds View 5/22/2011 Tornado F0 0 0 20K <br />4.3.1.4 Lightning <br />Hazard Identification <br />Ramsey County researched historical data from the NCDC and the NWS as well as information from past <br />newspaper articles relating to lightning strikes in Ramsey County. By definition, all thunderstorms are <br />accompanied by lightning. The electrical charge from lightning can potentially be as much as 100 million <br />volts. Lightning strikes proceed from cloud to cloud, cloud to ground, or where high structures are <br />involved, from ground to cloud. Lightning strikes in Ramsey County are most prevalent in May and <br /> <br /> <br />15 Source: National Climatic Data Center, http://www.ncdc.noaa.gov/oa/ncdc.html