May 1-7, 2024

Temperature

Average temperatures were anomalously warm for much of the region, especially the Ohio Valley (Figure 1). Much of Indiana and Ohio were 8-10°F above normal for the week, with pockets that averaged even higher than that. Elsewhere, from Missouri through most of Illinois, northern Indiana, Michigan and northern Ohio, average temperatures were 6-9°F above normal. In Iowa and Minnesota, average temperatures were only slightly above normal to start the month, with much of central and western Iowa near normal. Ohio had the largest temperature anomaly, with a statewide average temperature of 66.5°F, 10.4°F above normal. This was followed Indiana with a statewide average temperature of 67.5°F or 10.4°F above normal. In Iowa, the average temperature was only 0.6°F above normal.

Minimum temperatures were as much as 12°F above normal for the week in southern Indiana, northern Kentucky and southern Ohio (Figure 2). On May 4, Columbus Ohio; Dayton, Ohio; Mansfield, Ohio; and Zanesville, Ohio all observed record high daily minimum temperatures at 65°F, 65°F, 62°F, and 65°F, respectively.

Maximum temperatures were 8-11°F above normal throughout Indiana and even parts of Ohio (Figure 3). West of the Mississippi River, average maximum temperatures were mostly 2-4°F above normal ,and generally near normal across western Minnesota and western Iowa. Zanesville had a record high maximum temperature of 87°F on May 2.

Precipitation

Precipitation was centered mainly west of the Mississippi River this week, as norther Missouri, Iowa and Minnesota received over 200 percent of normal precipitation (Figure 4). It was even wetter in northwestern Iowa as precipitation eclipsed 400 percent of normal for the week. In Spirit Lake, Iowa, the local COOP station—which has been operational since 1893—recorded 3.36 inches of precipitation for the first week of May alone, despite the monthly normal being less than an inch more at 4.13 inches. Primghar, Iowa had its wettest May start since records began in 1895, with 4 inches of rain for May 1-7, slightly under the monthly normal of 4.11 inches. Conversely, much of the eastern Midwest had a dry start to the month, with less than 25 percent of normal precipitation in central Indiana. Frankfort, Indiana recorded no measurable precipitation for the first week of May for the first time since 2005 and the 15th time since 1914. In eastern Indiana, the week did end with some rain, including flash flooding in Franklin County and a high-water rescue just south of Batesville.

Drought continued to erode heading into May. D0 (abnormally dry) across the region was down from 34 percent of the Midwest to 25 percent, and D1 (moderate drought) was also down along similar margins from 18 percent to just under 10 percent (Figure 5), both of which have not happened since May of 2023. D3 (Extreme Drought) was also erased from Iowa, the first time D3 has not existed in Iowa since June of 2022.

Severe Weather

It was one of the most active weeks of severe weather so far this year with over 600 storm reports, over 100 of which were hail and 300 of which were wind (Figure 6).

Some of the largest hail reports came from Indiana and Michigan on May 7. In Michigan City, Indiana vehicles were damaged by 2-3 inch hail. There were multiple reports and images of 4 inch hailstones on social media, one from Union City, Michigan and another report from Leonidas, Michigan. While not a record, the last hailstones measuring 4 inches in Michigan were recorded in 2021. The same outbreak spawned multiple tornadoes, including an EF-2 with winds of 135 MPH tornado that touched down in Kalamazoo County, not far from Portage, Michigan, and damaged two mobile home parks.

As storms moved east, eastern Indiana and Ohio were affected, with two EF-2 tornadoes, both with winds of 120 mph, confirmed in Mercer County, Ohio. In Richmond County, Indiana, an EF-1 tornado with winds of 90 mph caused primarily tree damage. At least 5 tornadoes of varying EF-0 and EF-1 strengths tore through Warren County, Ohio, about halfway between Dayton, Ohio and Cincinnati, Ohio.