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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />GRAPHIC 4.3.2E <br />l...iennelpiin County Tornadoes 1950 <br />1111111111 F Scale lij� EF Scale <br />9 8 <br />8 <br />Va <br />OJ <br />O <br />5 <br />0 4 <br />4 <br />3 <br />rtt 3 2 2 <br />2. 1 <br />U <br />NVU�IPIRUk VU�PRUk <br />FO/onl-0 1-1./EFI. 1-2./onl-2. 1-3/El-3 1-4/El-4 1-5/El-5 <br />i.:m,/ l-5 <br />4.3.2.8. Future Trends Ble <br />When looking at trends of tornado occurrences, one must keep in mind how reporting has changed over <br />the last decade as well as population increase. With more people covering a larger geographical area than <br />100 years ago, there is bound to be more reports of tornadoes occurring because people are there to see <br />them. There seems to be no trend since 1954 of the occurrences of F1 and stronger tornadoes and <br />increase in tornado reports results from an increase in the weakest tornadoes, F0. If just looking at <br />stronger events being reported, you can run into the problem of changes in tornado damage assessment <br />procedures in trend identification. <br />Taking out changes in population and reporting measures, there is less trend in the number of tornadoes <br />per year, as in there doesn't seem to be a growing number of tornadoes each year, or less for that matter. <br />Research does show there seem to be more extreme swings in tornadoes per year. While years have <br />always varied in terms of number of tornadoes, they generally fell between a certain range. In the past <br />decade however, researchers have started seeing toad counts that have deviated well outside of that <br />range. Another trend researchers are seeing is the number of tornado days seems to be decreasing, while <br />the number of tornadoes per day has been increasing. <br />Researchers have also been looking into trends on when the 'tornado season' starts. The average start <br />days of tornadoes is March 22nd, and that has not changed (tornado season start is defined as first 50 <br />tornadoes of F1/EF1 strength have been reported). However, there have been later and early starts to the <br />season in recent years. Seven of the 10 earliest tornado starts have occurred since 1996, and four of the <br />latest starts occurred between 1999 and 2013 of 60 years of records. <br />77 <br />