Midwest Weekly Highlights - June 17-23, 2008
Cool and Dry, but Major River Flooding Continues
A persistent northwest flow aloft brought almost fall-like weather to most of the Midwest this week (Figure 1). Temperatures were well below normal southern Michigan and northern Ohio from Ohio westward through Missouri and eastern Iowa. Average daily temperatures ranged from 6°F to 4°F below normal in this region, and from 3°F to near normal across Minnesota and the western Michigan Upper Peninsula (Figure 2). The cooler temperatures combined with dew points in the 40s and 50s much of the week made for very comfortable weather (Figure 3).
After receiving two months worth of rain in the first two weeks of the month, rainfall was well below normal the third week of June (Figure 4). The exceptions were in western Missouri where thunderstorms formed on the edge of the cooler air mass, and in northern lower Michigan south into northeastern Ohio. The lack of rain was especially welcome in the flood-stricken areas of Iowa, Wisconsin, Missouri, Illinois, and Indiana. Major flooding continued on the Mississippi River, but flooding on most tributaries was subsiding. Major flooding was still occurring on rivers in southern Wisconsin (Figure 5). In Indiana only rivers at locations in the southeastern part of the state were near flood stage, but levels were declining steadily at the end of the week (Figure 6).
Scattered Severe Thunderstorms, Isolated Heavy Rain
Scattered thunderstorm occurred across most of the region this week, with severe weather reported at one time or another in all states except Minnesota.
Severe thunderstorms erupted across western Missouri into western Iowa on the afternoon of June 19, producing heavy downpours, hail, high winds, and at least one tornado (Figure 7). A tornado rated as EF1 touched down in Greene County, MO damaging several structures and uprooting numerous trees. Two to more than three inches of rain fell in southern Greene County and northern Christian County, producing some flash flooding (Figure 8). On June 20 a weak tornado briefly touched down in Pottawattamie County, IA, and on June 22 a tornado was sighted near Hubbard Lake, MI (Alcona County) in far northern lower Michigan, and one-inch hail reportedly covered the ground to a depth of six inches. Softball-sized hail (4.5 inches) was observed and photographed in Algonquin, IL (McHenry County) on June 20. Hail 2.75 inch in diameter was observed in Joplin, MO (Jasper County) on June 22.
Thunderstorms on June 21 produced flash flooding in Adrian, MI (Lenawee County), with water reported up to the hoods of cars. Southwestern Missouri had another round of heavy thunderstorms during the early morning hours of June 23. Southern Greene, Christian, and Taney Counties received another two to more than four inches of rain. The heavy rain caused flash flooding that closed a number of roads in these counties. There were also numerous reports of 1.00 to 1.75 inch hail with these storms.
June 23 flood status: Quad Cities
A levee breach early on June 17 at Carthage Lake three miles south of Gulfport, IL (Henderson County) on the Mississippi River flooded 9,000 acres of farmland and the village of Gulfport. A three-mile section of U.S. 34 was under up to seven feet of water, and Illinois Department of Transportation officials indicated the road may be closed up to six weeks.
On June 23, the state of Illinois announced a Flood Recovery Assistance Hotline to help flood victims with state assistance programs. To date, Illinois has declared 24 counties as state disaster areas (Adams, Calhoun, Clark, Coles, Crawford, Cumberland, Douglas, Edgar, Hancock, Henderson, Knox, Jasper, Jersey, Lake, Lawrence, Madison, Mercer, Monroe, Pike, Randolph, Rock Island, St. Clair, Whiteside, and Winnebago).
June 23 flood status: Indianapolis
Minor flooding was still occurring on the White River, mostly affecting bottomlands and a few low oil fields.
The flood waters rolled down the Cedar and Iowa Rivers and other tributaries into the Mississippi River, where major flooding and levee breaks occurred all week as the flood wave moved down the river from the Iowa/Illinois segment to the Missouri/Illinois segment of the river. At the end of the period, there were still some locations at major flooding levels in Iowa, including Iowa City and Ottumwa, but most of the major flooding had moved into the Mississippi River stretch from southern Iowa to St. Louis.
Cedar Rapids, the worst hit city, had 9.2 square miles, 1,300 city blocks, 3,894 single family residences and 818 commercial properties and government buildings inundated. Floods reached locations far outside the 100-year flood plain, resulting in many homes not eligible for flood insurance to be inundated. The 25,000 residents of Cedar Rapids uprooted by floods 12 feet above the 1993 previous record flood crest make up the majority of the nearly 40,000 people displaced from their homes in the region by the floods. Up to 400,000 cubic yards of trash and debris are expected to be generated during clean-up, more than the city produces in an entire year. A total of 70 counties in Iowa have now received Presidential disaster declarations, with 83 under a governor’s disaster proclamation.
Total crop loss in Iowa alone is near $3 billion, as 9% of corn acreage and 20% of soybean acreage was flooded, damaged, or never planted.
The U.S. Army Corp of Engineers produced maps for the Rock Island and St. Louis Districts along the Mississippi River showing the location of breeched levees and flooded areas (purple), and the locations of other levees with high potential for overtopping (red) and those in moderate danger (yellow). Hannibal and St. Louis in Missouri were handling the flood crest well, but a number of other small towns were wholly or partially flooded by levee failures or overtopping, including Winfield and St. Charles.
At the end of the period, the crest had passed southward to near St. Louis. This does not mean river communities are out of danger yet, as some levees have been standing against water for so long that they are becoming saturated, with structural failure possible even without overtopping. More rain could cause already weakened levees to give way. Several levees are in critical condition, and a number of small towns were wholly or partially flooded by levee failures or overtopping, including Clarksville,Winfield, Foley, and St. Charles. The Winfield case was especially illustrative of the fragility of some levees in the protection system, as the flood waters broke through a 3 inch tunnel dug by a muskrat and poured water out under pressure like a fire house. A worker commented to the St. Louis Post-Dispatch that the levee was so spongy that “it’s like walking on a waterbed." Many volunteers and National Guard troops have been able to keep most of the levees intact.