Laserfiche WebLink
Sherburne County Multi -Hazard Mitigation Plan, 2020 <br />removed from houses. Carports may be uplifted; minor cosmetic damage may occurto <br />mobile homes. <br />Large limbs break; shallow -rooted trees may be pushed over. Semi -trucks may be <br />50-64 knots overturned. More significant damage to old/weak structures occurs. Shingles, awnings may <br />(58-74 mph) be removed from houses; damage to chimneys and antennas occurs; mobile homes and <br />carports incur minor structural damage. <br />Widespread damage to trees with trees broken/uprooted. Mobile homes may incur more <br />65-77 knots significant structural damage; Roofs may be partially peeled off industrial/commercial/ <br />(75-89 mph) warehouse buildings. Some minor roof damage may occur to homes. Weak structures (e.g., <br />farm buildings, airplane hangars) may be severely damaged. <br />78+ knots Many large trees broken and uprooted. Mobile homes may be severely damaged; moderate <br />(go+ mph) roof damage to homes may occur. Roofs may be partially peeled off homes and buildings. <br />Moving automobiles may be pushed off dry roads. Barns and sheds may be demolished. <br />Source: (National Weather5ervice, 2018) <br />Windstorm History in Sherburne County <br />Sherburne County frequently experiences winds blowing at over 5o knots. According to NCEI records, <br />there have been 123 thunderstorm/high wind events reported from January 1955 through July 203.9, <br />with wind speeds of up to 95 knots. <br />In July of 2o3.8, severe thunderstorms were accompanied by wind gusts that reached 70 mph at the <br />airport in St. Cloud. Other wind gusts in the northern half of Sherburne County reached 55 mph. One <br />month earlier, the airport in St Cloud had measured a gust of 6o mph. <br />Winds of over 6o mph occurred near Becker in July of 203.0, where several trees with diameters of <br />between 3.3-3.5 inches were uprooted. In addition, a farm irrigation system was destroyed. Property <br />damage estimates totaled $250,000. On the same day, severe winds brought extensive damage to the <br />town of Elk River as well. Trees toppled, a farm fence was damaged, and tents and sheds were blown <br />over at the Sherburne County Fair. The property damage estimate was sioo,000. <br />Severe thunderstorms brought winds of up to 6o knots to Elk River in May of 3.998. Trees were blown <br />over and buildings damaged. The total property damage estimate for Sherburne County was s3 million. <br />In July of 3.997 a severe windstorm with winds of up to 95 knots wreaked havoc in Sherburne County: <br />five airplanes were overturned at an airport; a roof was blown off a lumberyard, which injured a <br />motorist; hundreds of trees were toppled; roofs were ripped from structures such as a school, <br />apartment building, and store; traffic lights went down; a restaurant was destroyed; and a police car <br />was blown off the road. <br />To determine the probability of future windstorm events in Sherburne County, all past -observed <br />windstorm events (thunderstorm wind, high wind, and strong wind) and the period in which they <br />occurred were examined. Based on the records in the NCEI Storm Events Database, the relative <br />frequency of windstorm events in the County is 3..9 events per year. This relative frequency can be used <br />to infer the probability of these events occurring in the future. <br />Page146 <br />