May 22-31, 2002: Warmer Temperatures and Reduced Rainfall Helps Farmers.

The May 22-31 period was somewhat less active than the previous portions of the month, but still had its share of heavy rain events. However, for the first time in May, more of the region received below normal amounts of rain than above normal amounts. Precipitation for the 10 days exceeded two inches in western and northeastern Missouri, eastern Iowa, northeastern Wisconsin, and northern Michigan (Figure 19). While these areas exceeded 100% of the normal precipitation total, parts of Midwest in central Minnesota and the eastern half of Kentucky received less than 25% of normal for the time of year (Figure 20). The cold streak in May also ended, with most of the Midwest having warm enough temperatures at the end of the period to bring the 10-day average to within +/- 2°F of normal (Figure 21). After a respite of one-week, a portion of the Midwest went back on the U.S. Drought Map; northwestern Minnesota slipped into the abnormally dry category due to a lack of rain recently (Figure 22, NDMC).

The period began with very cool but mostly dry conditions, with low temperature records set in several locations scattered throughout the Midwest. A frontal boundary sagged across the Midwest on the May 23-24, bringing the heaviest and most widespread rain event of the period to a band extending from southwest Missouri to northern Illinois. The front was drier but more violent on the 25th (Figure 23, NWS), with numerous cases of severe winds reported in Indiana and Ohio (Figure 24, SPC). A rapidly moving low pressure system brought rain to the northern Midwest on May 26, including a weak tornado in Arcadia, WI, that caused damage to some homes and buildings. After the 26th, the front was draped over the area in a quasi-stationary mode, and a high in the Southeast pumped warmer, more humid air into the area. Instead of widespread precipitation, though, each day from May 27 to 31 had some limited area that received moderate to heavy rains, while most of the region did not receive rain. Central Illinois experienced some heavy rain on the 28th, but only in isolated locations (Figure 25, NWS). However, flash flooding resulted in these places due to rains earlier in the month saturating the ground. On the 29th, a cluster of 4 tornado reports were made in far northwestern Minnesota, but no damage to property was reported (Figure 26, SPC). The month of May ended with the onset of summer-like warmth in most of the region. The Midwest also ended the month far wetter than the surrounding drought-plagued regions in the West and in the East (Figure 27, CPC).