Southern Midwest Cooler than Normal

Preliminary temperature data for this week ranged from 2.3°F below normal in Illinois to 2.5°F above normal in Michigan. Not too far behind Illinois were Kentucky, Missouri, and Indiana, all observing average temperatures at least 1.5°F below normal (Figure 1). Logan County, Kentucky was coolest with an average temperature of 65.7°F (5.2°F below normal). The lowest minimum temperature at this location was 47°F, which occurred on September 13. Northern Michigan had the warmest temperature departures with stations averaging over 4°F above normal. Ostego County, Michigan averaged 6.9°F above normal for the week. Wisconsin, Minnesota, and Ohio all had locations with temperatures 1-2°F above normal. Minimum temperature departures (Figure 2) outweighed the maximum temperature departures (Figure 3) this week.

Heavy Rain, Flooding in Southeastern Wisconsin and Northern Illinois

It seems as if each week highlights a new location that is impacted by heavy rain and flooding. In this week’s episode, southeastern Wisconsin and northern Illinois had locations that received 1.5 to 5 inches of rain (Figure 4). Racine County, Wisconsin measured 6.81 inches of precipitation, which was 6.04 inches above normal. The location received an astonishing 6.75 inches on September 12. The National Weather Service in Milwaukee, Wisconsin tweeted 2-day rainfall totals (September 10-12) were 6.32 inches in Jefferson, 6.97 inches in Waukesha, 5.28 inches in Milwaukee, and 7.04 inches in Racine. In Chicago, Illinois, heavy rainfall was measured ranging from 1.95 inches to 5.21 inches in Capron. The 16 and 17 District Chicago Police Scanner tweeted a picture of flooded vehicles at Irving Park/Kilbourn. Many of these areas that were mentioned were between 300 and 750 percent of normal precipitation for the week (Figure 5). There were 68 daily precipitation records that were broken or tied this week, with most occurring through northern Illinois and southeastern Wisconsin (Figure 6). East-central Indiana and northern Michigan received 125-300 percent of normal precipitation. On a statewide basis, Wisconsin was wettest with 144 percent of normal precipitation with Illinois and Indiana tying for second at 108 percent of normal precipitation. Not everyone received the heavy rain, though. The driest locations were southern Missouri and northwestern Minnesota, which both received less than 25 percent of normal precipitation. Statewide precipitation for Missouri was driest as the state averaged 37 percent of normal. As expected, the 7-day average streamflows were highest in the areas that received the most precipitation. Streamflows were intermittently below-normal in northern Missouri and more abundant in central/southern Iowa, north-central Illinois, and northeastern Indiana (Figure 7).

Drought Update

The total land in drought or abnormal dryness on the US Drought Monitor map increased by 4.15 percent compared to the previous week (Figure 8). Most of the expansionwas in the abnormally dry (D0) category in Michigan, Minnesota, Missouri, and Iowa. In southeast Iowa, Extreme Drought (D3) was introduced. There were improvements to the D0’s in central Indiana, Illinois, central Michigan, and in Wisconsin.