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Midwest Weekly Highlights - July 25-31, 2018

Cool Temperatures

Canadian high pressure settled over the central U.S. during the final week of July, leading to cooler than normal temperatures (Figure 1).  Most of Iowa, northern Missouri, Illinois and Indiana were 3-6°F below normal for the period, with Wisconsin, Minnesota, Michigan and Kentucky 1-4°F below normal.  Only the eastern U.P. of Michigan and eastern Ohio were near normal.  Maximum temperatures were even cooler from western Missouri through central Indiana (Figure 2).  Parts of central Illinois were as much as 9°F below normal.  Cloud cover and storms kept temperatures cooler than surrounding areas.  Most of the more than 100 daily temperature records were from record low maximum temperatures (Figure 3).

Dry for Most

Showers and thunderstorms were few and far between across most of the Midwest during the period (Figure 4).  Large areas of Iowa, Minnesota, southern Wisconsin, northern Illinois, Lower Michigan and southern Kentucky had less than half the normal amount of rainfall (Figure 5).  Some areas in northern Illinois and northwestern Iowa had less than five tenths of an inch for the period.  Only a few areas from northeastern Missouri through southern Indiana, and the U.P. of Michigan, had more than an inch of precipitation.  Most of this rainfall occurred through the mornings of July 30 (Figure 6) and July 31 (Figure 7).  Most of the precipitation in the U.P. of Michigan fell through the morning of July 26 (Figure 8).  Scattered severe weather was reported mainly in northern Ohio and northern Iowa (Figure 9).  A 2.75 inch diameter hailstone was reported near Blue Earth, MN (Faribault County) on July 25, while a weak EF-0 tornado was reported near Oregon, OH (Lucas County) on July 31.

Drought Expansion Continues

Another dry week across portions of northern Missouri and eastern Lower Michigan led to the expansion of drought in the July 31 U.S. Drought Monitor (Figure 10).  More than 65 percent of Missouri was classified in drought, compared to just over 50 percent on July 24 (Figure 11).  Extreme Drought also increased in northern Missouri to cover more than 17 percent of the state.  Meanwhile, moderate drought covered more than a quarter of Michigan (Figure 12).  Several counties in northwestern Ohio were also in drought.  More than 6.7 million people were estimated to be living in drought-affected areas.