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Sherburne County Multi -Hazard Mitigation Plan, 2020 To determine the probability of future droughts in Sherburne County we look at past -observed droughts. The USDM database was examined from January 2000—August 3.2, 2019 (1,023 weeks) for any occurrence of drought in the county, regardless of the duration or severity of the drought. According to the weekly reported data, the relative frequency of the county experiencing drought conditions >_ Di is 3.2.8 weeks per year and the relative frequency of drought conditions >_ D2 is 3.2 weeks per year (National Drought Mitigation Center, 2o3.8). The relative frequency of past droughts can be used to infer the probability of similar droughts occurring in the future. In addition to highlighting specific notable droughts the USDM database was examined from January 2000 — August 12, 2019 (1,023 weeks) for any occurrence of drought in the county, regardless of the duration or severity of the drought. According to the weekly reported data, the county experienced drought conditions >_ D1 24% of the weeks and drought conditions >_ D2 6% of the weeks. When comparing the two most recent five-year timeframes (203.4-2oi8 & 2oo9-2013), the data shows either a decrease or no change in each drought category >_ Do. Table 28 shows the breakdown of this comparison. Table 28. Average Percent of Sherburne County's Lana Area by Drought Category Timeframe No Drought DO Di D2 2009-2013 47.67% 23.32% 15.6iO/o 9.55% 3.84% 0% 2014-2018 84.90% 11.660/6 3.45% 00/0 00/0 0% % Change 78.1% -50% -77.9% -100% -100% 0% Drought and Climate Change In 2007, 24 Minnesota counties received drought designation, while seven counties were declared flood disasters; in 2012, 55 Minnesota counties received federal drought designation at the same time ii counties declared flood emergencies (MN Environmental Quality Board, 203.4), and in May of 2015, over go% of Minnesota was undergoing severe or moderate drought (MN DNR, 2015). Droughts have been happening throughout Minnesota's history but it is not yet clear the degree at which climate change may impact future droughts (International Climate Adaptation Team, 203.3). While there was no apparent change in drought duration in the Midwest overthe past century (Dai, ZOii), the average number of days without precipitation is projected to increase in the future (National Climate Assessment Development Advisory Committee, 2013). The climate models used in the 203.4 National Climate Assessment projects Minnesota to have an increase in days over go°F by mid-century; however, the future drought situation is less clear. The climate model run with the lower emissions scenario projects no significant change in the number of consecutive days of no rain, while the higher emissions scenario show an increase in dry periods, increasing Minnesota's drought risk (Minnesota Pollution Control Agency, 203-7). These climate models are shown in Figure 22. Page178