Midwest Weekly Highlights - August 11-17, 2010

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Warm Temperatures

Temperatures were warm across the region in the second week of August. Northwest Minnesota was near normal and temperature departures increased to the south and east, exceeding 7°F in western Kentucky (Figure 1). The persistently warm temperatures contributed to slight drought expansion in western Kentucky (Figure 2). Daily temperature records during the week were almost exclusively record highs. Heat warnings and advisories were issued for large parts of the Midwest on several days (Figure 3).
 

Variable Rainfall

Rainfall varied from nothing in some locations, such as west central Indiana, to as much as 6" to 8" in parts of Iowa and Wisconsin (Figure 4). Areas receiving less than 25% of normal extended from the southwest tip of Indiana northward to Lake Michigan, as well as southern Missouri, southwest Iowa, east central Ohio, and northern lower Michigan (Figure 5). Significant areas in Minnesota, Wisconsin, and Iowa received over 400% of normal as did additional isolated locations. More than 250 daily precipitation records were set during the second week of August.
 

Iowa Flooding

Heavy rains that fell in central Iowa on the 8th, 9th, and 10th caused flash flooding and pushed area rivers higher over the next few days (Figure 6). The Skunk River and its tributaries were well above flood stage, and in some places topped the 1993 flood levels. Roads throughout central Iowa were closed due to high water, however I-80 remained open when the South Skunk crested before overtopping the roadway.

A teen driver was killed in Des Moines (Polk County) when her car was swept into a flooded creek. Des Moines, Ames (Story County), and Colfax (Jasper County) were hard hit with hundreds of evacuated homes and thousands more flooded. At least 40 homes in eastern Des Moines were declared "unsafe to occupy" due to the damage. Flooding was responsible for broken water mains in Ames which drained water towers and left the town without safe drinking water for several days. Hilton Coliseum at Iowa State University in Ames filled with five feet of water and the nearby conference center also flooded. Damage extended downstream in Mount Pleasant (Henry County) when the flood waters surged through a campground causing thousands of dollars damage to roads and property.
 

Western Wisconsin Flash Flood

On the 11th a heavy downpour dropped as much as 6" of rain in Pierce County and St. Croix County, Wisconsin. The rising waters washed out bridges, damaged homes, and even whisked dozens of cattle downstream. The Rush River rose quickly closing many roads including ramps on I-94. In Dunn County sinkholes and mudslides were reported. The waters receded quickly as well limiting the flooding to a day or two, depending on the location.
 

More Severe Weather for Minnesota

A busy summer for severe weather in Minnesota continued. Tornadoes were reported on the 11th (Watonwan County), 12th (Lac Qui Parle, Strearns, and Dakota Counties), and 13th (Dodge, Olmsted, and Blue Earth Counties). The tornadoes brought the preliminary Minnesota total for the year to 122, well above the previous record of 74 tornadoes in 2001. Minnesota is also the unexpected 2010 top state, well ahead of Texas (87) and Kansas (80).
 

-MST-