Midwest Weekly Highlights - July 15-21, 2009
Record Cool Temperatures Across the Midwest
The third week of July continued the cool pattern across the Midwest. Temperatures were well below normal across the region, ranging from about 6°F below normal in Ohio to as much as 12°F below normal in eastern Iowa(Figure 1). Cooler than normal temperatures were evident in both the maximum and minimum temperatures but were most pronounced in the maximum temperatures (Figure 2). The western half of the Midwest had maximum temperatures that averaged 10°F below normal for the week.
Eight stations had record low maximum temperatures that either tied or set the record for all of July. Overall more than a thousand records were set during the week at locations all across the region (Figure 3). A four day stretch from July 17th-20th recorded over a hundred records each day peaking with 439 records on July 18th.
Rainfall again varied across the region during the third week of July (Figure 4). The heaviest rain fell in central Minnesota and southwest Missouri with each exceeding 200% of normal over a large part of the state. Most of the remaining areas in the Midwest received less than normal rains with a minimum of less than 5% of normal in west central Wisconsin and a second local minimum in west central Ohio receiving less than 25%. The US Drought Monitor reflects both the continuing drought in the upper Midwest and the emerging dryness in Ohio (Figure 5).
July 15th storms struck southeast Missouri and western Kentucky blowing down trees and damaging roofs. The wind overturned a semi truck on I-55 in New Madrid County, Missouri. The following day, a storm struck Iuka, Illinois (Marion County). The storm, initially thought to be a tornado but later determined to be a downburst event, brought down large trees, flattened corn, damaged buildings, and covered the ground with hail up to 1" in size. Hail and wind damage was also reported around St. Louis and Chicago with the largest reported hail (up to 1.75") in Washington County, Missouri. In Chicago at the 57th St. Beach, a life guard boat was capsized by winds estimated at 50 miles per hour.
The only severe weather on July 17th struck central Ohio (Franklin and Licking counties) with wind damage to trees and hail up to 1" in diameter. After 2 days without severe weather, July 20th brought hail up to 1.5" in Laclede County, Missouri and hail in eastern Kentucky. Martin County received hail up to 1" in size and Pike County was hit with smaller hail that accumulated to several inches deep.
On July 21st (Washington County, Minnesota), lightning struck a tree killing one of two teenagers who were in the yard. Later in the evening, nickel sized hail shredded some corn fields in Blue Earth County, Minnesota. The hail piled up in town, leaving a mound several feet wide that had not melted the following morning. Golf ball sized hail (1.75") was reported in Cottonwood County and Washington County among numerous hail reports in southeast Minnesota. Eastern Ohio also had multiple reports of large hail on the 21st.
There was no river flooding in the Midwest during the week but there were reports of flash flooding. Minnesota received significant rains on the 14th into the 15th that led to flash flooding in the Brainerd Lakes area. On the 17th, Fort Wayne, Indiana's Three Rivers Festival was interrupted by 1.5" of rain that fell in two hours. The rapid runoff to the sewer system trapped air that erupted as small geysers from manholes in the city. In southwest Missouri, more than three inches of rain caused widespread flooding of roads on the morning of the 21st.