Midwest Weekly Highlights - August 25-31, 2014

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Heat Wave in Central Midwest Kicks Off the Week

The last week of August kicked off with heat advisories and warnings in the central and southwest portions of the Midwest (Figure 1). Temperatures were between 95°F and 105°F in Missouri, and 90°F to 100°F elsewhere in Illinois, southern Iowa, and western Kentucky (Figure 2). Of course as is the case with any heat wave, the humidity was responsible for pushing the heat index values well over 100°F (even over 110°F in some areas). Nighttime low temperatures also remained elevated during the heat wave, ranging between 70°F and 80°F across Missouri, Illinois, and western Kentucky (Figure 3).

Overall, weekly temperatures were above average for a majority of the Midwest, with the highest departures of 5°F to 6°F in portions of Missouri, Illinois, and southern Indiana (Figure 4). On the other hand, the Upper Midwest did experience below normal temperatures, mainly across Minnesota, northwest Iowa, northern Wisconsin and northern Michigan. The departures in these regions were 1°F to 5°F below normal. Minimum temperatures were above average, especially in the central Midwest where they were 6°F to 8°F above normal (Figure 5).

Mix of Above and Below Normal Precipitation

Weekly precipitation totals over 2" fell across portions of Iowa, southeastern Minnesota, and Wisconsin during the last week of August, with the highest accumulations of 3" to 5" in western Iowa (Figure 6). These totals were at least 200% of normal, with western Iowa experiencing 300% to 750% of normal precipitation (Figure 7). There were several areas with below normal precipitation, including northwest Minnesota, Missouri, and much of the eastern Midwest.

Severe Weather, Mainly High Wind Reports

There were several severe weather reports across the Midwest during the last week of August, many of which were high wind reports (Figure 8). The majority of the high wind reports occurred on August 31st, mainly across Iowa and western Missouri. In Guthrie County, Iowa, winds measuring 80 mph were reported, along with associated damage reports of downed power lines. A small tornado was reported in Elmhurst, Wisconsin (Langlade County) on August 29th, with only tree damage reported.

-MW-
Extension Climatologist for Illinois-Indiana Sea Grant and the Midwestern Regional Climate Center