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Sherburne County Multi -Hazard Mitigation Plan, 2020 portion of a tropical cyclone. Funnel clouds are rotating columns of air not in contact with the ground; however, the column of air can reach the ground very quickly and become a tornado. Since 2007, tornado strength in the United States is ranked based on the Enhanced Fujita scale (EF scale), replacing the Fujita scale introduced in 3.971. The EF scale uses similar principles to the Fujita scale, with six categories from zero to five, based on wind estimates and damage caused by the tornado. The EF Scale is used extensively by the NWS in investigating tornadoes (all tornadoes are now assigned an EF Scale number), and by engineers in correlating damage to buildings and techniques with different wind speeds caused by tornadoes. To see a comparative table of F and EF scales, see httD://WWW.SDC.noaa.aov/faa/tornado/ef-scale.html. In Minnesota, the peak months of tornado occurrence are June and July. The typical time of day for tornadoes in Minnesota ranges between 4:00 p.m. and 7:00 p.m. Most of these are minor tornadoes, with wind speeds under 3.25 miles per hour. A typical Minnesota tornado lasts approximately io minutes, has a path length of five to six miles, is nearly as wide as a football field, has a forward speed of about 35 miles an hour, and affects less than o.i% of the county warned. Tornado History in Sherburne County According to the NCEI, 12 tornadoes were reported in Sherburne County between 195o and July 203.9, causing one death, 12 injuries, and over $2.5 million dollars in property damage. Tornado classification ranged from EFo/Fo to F2 on the Enhanced Fujita Scale/Fujita Scale. These 12 tornadic events occurred in 9 of the 69.4 years on record. The most recent tornado occurred on March 6, 203.7, when an EFi tornado touched down west of Zimmerman, before traveling northeast for nearly nine miles. The tornado dissipated before reaching Highway 3.69. Winds of iio mph occurred, and the encompassing storm also produced tree damage due to non-tornadic winds. This tornado, one of two on this date, was the earliest reported tornado in Minnesota, occurring 12 days earlier than the previous record (see Tornadoes and Climate Change for further information). Two EFo tornadoes occurred in Clear Lake on June 3.7, 203.0. While a few dozen trees sustained damage, no major property losses were reported. An EFo tornado occurred near Becker in July of 20o8. Over its path of four miles, the tornado downed trees, destroyed sheds and damaged homes. Approximately s3oo,000 dollars of crop damage also resulted. The most severe tornado to occur in the county occurred in July of 1967. Ranked as an F2, the tornado traveled nearly 3.5 miles and its width reached 200 yards. In Sherburne County, the tornado caused one death, 12 injuries, and $2.5 million in property damage. Figure 7 below shows tornado touchdown points and tracks in Sherburne County. Historic tornado events in the county are listed in Table 3-7. Page142