Temperature and Precipitation Anomalies.
The Midwest experienced its 11th wettest May on record, continuing a trend from earlier in the season. The climatological spring (MAM) precipitation total was ranked 5th greatest for the Midwest since 1895. Missouri recorded its 2nd wettest May on record, and Illinois, Indiana, and Missouri all ranked in the top 5 wettest springs. Some locations in the Midwest received more than a foot of rain during May, especially in southern Missouri (Figure 1). Most of Missouri and southern Illinois received more than 200% of normal precipitation for May (Figure 2). Considerable flash flooding and river flooding took place. The clouds and rain led to the Midwest having the 15th coldest temperatures for May, with every state below average. The northwestern portion of the region was 6-8°F below normal, while the southeastern portion of the region was only 1-2°F below normal (Figure 3). Michigan had its 12th coldest May, and Minnesota its 15th coldest. The Midwest was virtually drought-free by the end of May, with the exception of some drier areas in northern Minnesota and some subsurface deficits in parts of Iowa (Figure 4, Climate Prediction Center, CPC).

Extreme Events and Impacts.

Severe Flash Floods in Eastern Kentucky, May 2-3.
Storms on May 2-3 dropped up to 4 inches of rain in 6 hours and caused tremendous flash flooding in the area where Kentucky, Virginia, and West Virginia meet. One person is missing from Kentucky and presumed drowned, and 1,500 hundred families had to evacuate in Pike County. Two long-lived mesoscale convective systems crossed the Midwest starting on May 1 and early May 2 (Figure 28, NWS), leaving behind trails of severe weather reports (Figure 29, SPC), including train cars blown off a track in Illinois, and contributing to the rain in the Appalachians. More rain arrived later on the 2nd, as a series of severe thunderstorms trained through eastern Kentucky and points further east (Figure 30, U of Illinois Dept. Of Atmospheric Science, UIUC DAS). Rain totals had reached 5 inches in places over the previous two days (Figure 31, NWS), when even heavier and more persistent rain fell overnight. The death toll across the 3 states was at least 7, with a number of people still missing, about 200 homes were destroyed, and 2,000 homes were damaged.

Regional Severe Weather Outbreak, May 6-9.
Another severe weather outbreak occurred in the region on May 6-9. Each day, parts of Missouri, Illinois, and Indiana were hit with storms. The accumulated precipitation was especially large in the Missouri Ozarks (Figure 32, NWS), where more than 4-6 inches of rain caused flash flooding that claimed 2 lives and weakened the bed of a train track where 3 locomotives derailed. A strong squall line developed ahead of a cold front from Wisconsin through Missouri and then proceeded eastward across the region on the evening of May 8-9 (Figure 33, UIUC DAS). Severe weather was widespread, especially strong straight-line winds (Figure 34, SPC). In the southern Illinois town of Centralia, 2 people died in separate mobile homes in the same park as strong winds overturned and smashed them. Another 13 were injured and required hospitalization. Flooding caused more evacuations in Illinois, Indiana, and Kentucky. Tremendous amounts of standing water contributed to concerns about a bumper crop of mosquitoes that carry the West Nile virus.

Major Flooding in the Midwest, May 11-21.
Flash floods resulted in 9 deaths in Missouri, 2 before May 11 and 7 during the May 11-21 period. Flooding along the Missouri River was moderate, only 5-9 feet above flood stage, but major flooding more than 10 feet above flood stage was observed on the Grand River, Meramec River, and the Mississippi River, as well as many smaller tributaries. Transportation was disrupted on several rail corridors due to flooding, and the westbound lanes of the Mississippi River bridge at Alton, IL, were closed by flooding, along with many state roads. Hydroelectric energy production at dams in the Ozarks was shut down for several days for flood control purposes. More than 20 acres of downtown Crystal City, MO (30 miles south of St. Louis), were under water from the Mississippi River by May 20. Unfortunately, a long planned construction of a levee around Crystal City was slated for commencement later this fall. The Grand River covered more than 38,000 acres of farm lands with water in north-central Missouri. The Mississippi River at St. Louis was well below 1993 levels, cresting at 38.9 feet, or 8.9 feet above flood stage; this was still the 13th highest river crest on record. Cape Girardeau, MO, escaped damage with only 3 feet of freeboard on their flood wall, as the Mississippi River roared by at 13.7 feet above flood level (4th highest crest on record). On May 21, a federal disaster declaration already in place for tornado damage during the first week of May was expanded to include counties suffering from flooding in the last rains (Figure 35, Federal Emergency Management Agency, FEMA).

A single drowning death was reported in Illinois flooding during the period, although major flooding was widespread in the state. The Mississippi, Ohio, and Wabash Rivers on the state borders and the Illinois and Sangamon Rivers in the state interior all reached major flood levels more than 10 feet above flood stage (Figure 36, NWS). More than 480 inmates volunteered to aid in filling tens-of-thousands of sandbags for communities along the flooding rivers, and 80 Illinois Department of Transportation trucks were moving sand and equipment . About 23 separate state highway closures were forced by flooding, disrupting transportation. Barge traffic along the Illinois River was also suspended, costing operators $250,000 a day in lost revenues. While most of the residents of Grafton, IL, moved to higher ground after the 1993 flood, the remainder of the town was flooded by the Mississippi River, which reached 10 feet above flood stage at that location (Figure 37, USGS). The Ohio River at Cairo, IL, reached 12 feet above flood stage (7th highest crest on record), and the Wabash at Mt. Carmel, IL, was more than 13 feet above flood stage (4th highest crest on record). The town of Urbandale, IL, just north of Cairo suffered severe flooding that displaced several hundred residents from homes, destroying at least 30 homes and businesses. While the major flooding along the boundary rivers was spectacular, the more unusual flooding took place in the interior of Illinois. The Illinois River at Beardstown reached 14.7 feet above flood stage, its third highest level and only about 1 foot below the 1943 record flood (Figure 38, U.S. Army Corp of Engineers, USACE). The Sangamon River at Riverton, IL, reached 11.7 feet above flood stage at the gauge, the 3rd highest crest at that location (Figure 39, USACE). Several towns along the two rivers had even more difficulties, with a partial levee breech at Mechanicsburg, IL, flooding the water treatment plant. Very large areas of ground near rivers were covered with water, and there also was standing water in low-lying fields away from streams. A federal disaster declaration has been made for both the tornado and storm damage the first week of May and some of the flooding since that time (Figure 40, FEMA). A considerable area along the Illinois River and in central Illinois was undergoing a preliminary damage assessment and may be added to the federal disaster area.

In Indiana, the Kankakee, White and Wabash Rivers were especially hard hit during the recent heavy precipitation. Approximately 155 families were displaced by flooding, and the Wabash covered an area of agricultural land 3-4 miles wide at its lower reaches. About 12 homes were destroyed and more than 270 homes were damaged by flooding in Indiana. The White River above St. Petersburg crested about 10.5 feet above flood stage (Figure 41, USGS), and the Wabash River at Mt.Carmel, IL, crested more than 13 feet above flood stage (Figure 42, USGS). Much of Noblesville, IN, was inundated by the White River.