Above Normal Temperatures

For the first week of August, all Midwestern states averaged above normal temperatures. Preliminary temperature data ranges from 1.1°F (Minnesota) to 6.3°F (Missouri) above normal. Despite Minnesota’s average temperature being above normal, there were locations in northern Minnesota that experienced up to 1°F below normal for the week (Figure 1). Much warmer temperatures were recorded at the Joplin Regional Airport, located in Jasper County, Missouri, which had an average temperature of 87.5°F (7.2°F above the 1991-2020 climatological average). The station’s highest maximum temperature was 102°F, occurring on August 3, and averaged a maximum temperature of 99°F for the week. Most stations in the Midwest averaged 1-5°F above normal for maximum temperature, but did have stations in Missouri and Iowa in excess of 5°F above normal. Despite the warmer maximum temperatures, Kentucky was more seasonable and northern Minnesota was 1-5°F cooler than normal (Figure 2). Minimum temperatures were near normal in Minnesota to as much as 6°F above normal for everyone else in the Midwest (Figure 3). There were 37 maximum and 127 minimum high temperature records broken or tied this week throughout the Midwest.

Heavy, Isolated Rainfall Totals

Preliminary state average precipitation totals were near to above normal across the Midwest. Kentucky averaged 250 percent of normal rainfall and Iowa averaged 102 percent of normal rainfall. Variability in rainfall totals existed within each state, but the most notable differences occurred in northern/southeastern Missouri, northeastern/southwestern Iowa, western Illinois/Illinois, and northwestern/southern Minnesota (Figure 4). Northwestern Minnesota, southwestern Iowa, western Illinois, and northeastern Missouri all received less than 0.2 inches (less than 50 percent of normal rainfall) of rain this week and the other mentioned locations received up to 2 inches and in some cases more than 2 inches of rain (over 200 percent of normal) (Figure 5). Jasper County, Illinois, measured 7.19 inches of rain. On August 1, 4.61 inches of rain fell at this station. Eastern Kentucky received additional rains this week, resulting in 6.35 inches on already saturated soil from the previous week’s flooding event. Most stream flow readings were above normal to high in Kentucky, southern Missouri, and southern Illinois as a result of the continued heavy rains (Figure 6). On August 8, the National Weather Service Quad Cities (IA/IL) tweeted that there were eight stations that measured more than 6 inches of rain in 48-hour times (maximum of 11.25 inches at Freeport 1.2E). In total, there were 133 daily precipitation records that were broken or tied this week. The National Weather Service Chicago also created a summary for this event.

US Drought Monitor

In the August 2 US Drought Monitor, there was improvement to the Moderate Drought (D1) in southern Iowa and northern Wisconsin (Figure 7). The Extreme Drought (D3) in southern Missouri improved, but expanded in south-central Missouri. Minor adjustments were made to the D1 in Indiana and Illinois. Overall, there was 2.74 percent increase (15.26 percent to 18.00 percent) in the total Midwestern land in a drought category.

Storm Reports

There were 36 hail and 224 severe wind reports in the first week of August. Most of the reports occurred between August 1-3. Several trees were uprooted and wind damage to buildings was reported through Illinois, Indiana, Kentucky, and Michigan on August 1 (Figure 8). Two injuries resulted in Kentucky from falling trees. On August 2, hail 2.0 inches in diameter was reported in St. Louis County, Minnesota, and thre were several wind reports through Illinois, Michigan, Minnesota, Missouri, and Wisconsin (Figure 9). Also, an 81-mph wind gust was measured in Renville County, Minnesota, with several reports of large trees down, billboards blown over, and damage to buildings. August 3 brought more of the same with widespread wind damage through Iowa, Illinois, Indiana, Kentucky, Michigan, Missouri, Ohio, and Wisconsin (Figure 10). A large tree limb fell onto the road in Cass County, Michigan, and a 17-year-old tragically died as result of hitting the tree while driving. Additionally, a 79-mph wind gust was measured at Calumet County, Wisconsin.