August 22-31, 2024

Temperature

Average temperatures were 1-3°F above normal for most of the region this week (Figure 1). Isolated pockets of the Ohio Valley, southern Michigan and northern Minnesota were 3-4°F above normal.

Minimum temperatures were as much as 5°F above normal in northern Minnesota, and similarly warm for much of the Upper Midwest (Figure 2). Through much of the Ohio Valley, temperatures were near normal and 1-3°F below normal in eastern Kentucky. A station in Washington, Indiana observed a minimum temperature of 49°F on August 22, the coldest August temperature in over 10 years at that station. A station in Decorah, Iowa observed three consecutive days of minimum temperatures at or above 73°F from August 25-27 for the third time since records began in 1893.

Maximum temperatures were above normal for the entire region (Figure 3). They were most above normal across the Ohio Valley where maximum temperatures were 7-9°F above normal. Elsewhere, maximum temperatures were generally 3-6°F above normal. Rockford, Illinois, observed a temperature of 98°F on August 27, the warmest August temperature in Rockford since 2003. Evansville, Indiana observed a temperature of 101°F on August 29, the warmest August temperature in Evansville since 2010. Louisville, Kentucky also observed its warmest August temperature since 2010 with a maximum of 102°F on August 29. There were over 500 record high temperatures across the region during the final week of August (Figure 4).

Precipitation/Drought

With high pressure dominant across the Ohio Valley for much of the second half of the month, precipitation was negligible this week (Figure 5). In fact, the Missouri Bootheel, far southern Indiana, and western Kentucky observed no precipitation. Most of Kentucky, Ohio, Indiana and Michigan observed 50 percent or less of normal precipitation. The most precipitation fell in the Upper Midwest, specifically western Wisconsin and much of Minnesota, where it was 125-150 percent of normal.

The areas that needed the most rain got the least. By August 27, D4 (exceptional drought) had been introduced to a small sliver of southeastern Ohio (Figure 6). This was the first time D4 was observed in Ohio since the Drought Monitor began in 2000. D1 (moderate drought) expanded in parts of eastern Indiana and regions of Missouri. Abnormally dry conditions expanded in isolated spots across the region.

Severe Weather

There were over 500 storm reports this week, and over 450 were wind reports (Figure 7). The first system moved through the region august 26-27, spurring an outbreak of storms across Minnesota and northern Wisconsin. A brief tornado touched down in Brown County, Minnesota on August 26. On August 27, 2.5 inch hail was reported near Woodstock, Illinois, and a 76 mph straight-line wind gust was reported at Detroit Metro International Airport. These storms caused over 365,000 power outages and prompted school closures across southern Michigan.

Another outbreak produced more tornadoes and wind damage on August 29 across eastern Minnesota and western Wisconsin. There were six tornadoes, including four EF-1 tornadoes, on August 29. However, straight-line wind gusts were just as noteworthy, with an 80 mph wind gust in Anoka, Minnesota on August 29.