Continued Relief from the Heat

Much of the Midwest had average- to below-average temperatures (0-4°F below normal) this past week (Figure 1). Northern Minnesota was the coolest, flipping last week’s temperature patterns. For example, Saint Louis County’s average temperature was 5.5°F below normal. However, southern and eastern portions of the Midwest experienced above-average temperatures with average temperatures in southern Missouri up to 5°F degrees above normal. Howell County, Missouri set a record high temperature (109°F) while average temperatures were 9°F above normal. Average maximum temperatures had the largest widespread cooling pattern while average minimum temperatures were above normal for the southern and eastern Midwest (Figures 2 and 3). There were 51 maximum and 70 minimum daily high temperature records broken or tied across the southern Midwest. On the other hand, there were 15 minimum and 65 maximum daily low temperature records broken or tied in the western Midwest this week.

Record Rainfall Causes Catastrophic Flooding

While the central to northern Midwest received below average and variable precipitation, the southern Midwest was drenched throughout the week. A large portion of the southern Midwest received at least 4 inches of rain (Figure 4) and 3 to 7.5 times the average rainfall (Figure 5). The area spanning from Missouri through southern Illinois and Indiana into Kentucky was hit the worst with much of the area receiving 3 to 7 inches above normal (Figure 6). Perry County Kentucky recorded 11.91 inches of rain with 8 inches falling in one day. Saint Charles County Missouri recorded 14.87 inches of rain with 12.34 inches falling in one day in St Peters. St. Louis had a record-setting single day rainfall total of 8.64 inches, leading to flash flood conditions across the area. Belleville station in Illinois was another heavy-hit location, receiving nearly 8 inches of rainfall within 6 hours. Eastern Kentucky was under the bullseye as rainfall totals soared, leaving towns under water, and killing at least 37 people. Much of this week’s record rainfall took place on a single day and caused unprecedented flash floods for the southern Midwest. This includes record setting flood levels for streams and rivers in affected areas (Figure 7). There were 146 daily precipitation records broken or tied across the Midwest this week.

Missouri Drought Worsens

The US Drought Monitor map this week was largely unchanged, except for Missouri. There was a large expansion of extreme drought (D3) conditions in southern Missouri and a small expansion of extreme drought conditions in Iowa (Figure 8). This was a 2.37% increase in area affected by extreme drought. However, the latest drought monitor map for this week was valid for July 26, so much of the week’s historic rainfall had not yet taken place. This will likely impact the drought monitor for the following week and means that this drought monitor may not be indicative of true drought conditions at the week’s end.

Severe Weather Reports

There were 10 tornado, 47 hail, 4 large hail, 423 wind, and 27 high wind reports over this past week (Figure 9). Most the severe weather was in a swath that encompassed portions of Minnesota, Iowa, Wisconsin, Illinois, Indiana, Michigan, and Ohio.

July 22 - There were 3 EF-0 tornados reported in northern Illinois that were from the same storm system that produced dozens of wind reports and multiple hail reports. This system tracked through eastern Iowa, northern Illinois and Indiana, and the very southeastern corner of Wisconsin.

July 23 - Multiple rounds of severe weather struck the Midwest, resulting in 4 tornadoes. The strongest of which was an EF-1 in Miami County, Ohio. These storm systems also produced a swath of hundreds of wind reports with a report of 69 mph in Crawford County, Iowa. There were dozens of hail reports, with 4 being at least 2 inches in diameter.

July 31 - Two Tornadoes were reported; the largest of which touched down in Logan County, Illinois as an EF-1. There were also several wind reports produced by the same storm.