July 24-31, 2002: Drought Develops in the Ohio Valley.

The period of July 24-31 included the most widespread rain in the Midwest since mid-June. Totals greater than 2 inches fell in northeastern and southeastern Minnesota, eastern Iowa, central Illinois, and parts of southeastern Michigan (Figure 28). While this did not make up for prior rain deficits in most of the Corn Belt, it did at least arrest the decline in crop quality in some of these areas. Unfortunately, a few locations received less than 50% of the normal rain totals for the week and have suffered more crop deterioration, including southeastern Missouri, southern Illinois, and southern Indiana (Figure 29). Temperatures were 3-6°F above normal in most of the Midwest, with some less anomalous temperatures in the central Corn Belt (Figure 30). The National Agricultural Statistics Service reports for the week indicate some improvement in topsoil moisture in Illinois, Iowa, Michigan, Minnesota, and Wisconsin, although many of these states still have more than 50% of farm soils short or very short of soil moisture. The U.S. Drought Monitor indicated some expansion of abnormally dry conditions in Wisconsin, Michigan, and Missouri, with a new area of moderate drought north of the lower Ohio River in southern Illinois and Indiana (Figure 31, NDMC).

The precipitation during the period was often intense and limited in spatial extent, but the events in combination created a considerable degree of coverage over the 8 days. Storms visited the northern Midwest as a cold front advanced on the 24th and 25th, then shifted to the central latitudes of Iowa and Illinois on the 26th. The boundary then started returning north as a warm front, bringing copious rain to parts of eastern Iowa and Illinois (Figure 32, NWS). The accumulation of precipitation cross eastern Iowa (Figure 33, NWS) and central Illinois (Figure 34), NWS) during the period July 24-28 brought great assistance to the corn and soybean crops, but also led to power outages and wind damage in a number of small communities and a few cities. Another cold front moved south on the 29th, bringing more heavy storms to southern Minnesota, central Wisconsin, and parts of northeastern Indiana and northwestern Ohio. Finally, at the end of the month, two severe squall lines raked the Upper Midwest on July 30-31, bringing severe weather to northern Minnesota, Wisconsin, and Michigan (Figure 35, SPC).