Rain-Free Week for Much of the Midwest
A large portion of the Midwest did not receive any precipitation during the third week of August (Figure 1), which was anywhere from 0.6" to 1.2" below normal for these locations (Figure 2). Despite the overall dryness, there were some locations with above normal rainfall. Western Iowa and western Kentucky received between 1" to 1.5" throughout the week, which was 125% to 300% of normal (Figure 3). Much of the rainfall in Iowa came during an event on the 14th, while the rainfall in Kentucky was the result of an event that spanned from the 16th to 17th. With the widespread low precipitation in the region, there were just a handful of daily precipitation records set throughout the week.
The low precipitation during the week resulted in the expansion of dry conditions and drought in the Midwest. The August 20th release of the US Drought Monitor indicates that almost 45% of the region is classified as abnormally dry (an 18% increase from last week) and just under 8% of the region is classified as experiencing moderate drought (D1) (Figure 4).
Above Normal Temperatures in Upper Midwest, Below Normal Elsewhere
Below normal temperatures continued throughout much of the region during the third week of August, concentrated in the central and southern Midwest (Figure 5). Missouri experienced the largest departures with average temperatures 7°F to 9°F below normal. The widespread below normal temperatures in the central and southern Midwest set a significant number of daily record low temperatures.
Despite the below normal temperatures in the southern half of the Midwest, above normal temperatures spanned across much of Minnesota, northern Wisconsin, and northern Michigan. Northern Minnesota experienced temperatures that were 6°F to 7°F above normal for this time of year. Red Lake Falls, MN (Red Lake County) reported a maximum temperature of 97°F on August 20th, which is 18°F above the normal maximum temperature for this day, setting a new daily record high for this station (Figure 6).
Severe Weather Late in Week
A majority of the severe weather reports came on one day, August 21st, when a storm system moved through the upper Midwest (Figure 7), bringing hail and strong winds to portions of northern Iowa, Minnesota, Wisconsin, and Michigan (Figure 8). A few scattered reports of hail and strong winds were also reported in Kentucky and Ohio on the 21st.
Growing Season Update
The cooler than normal August weather has delayed development of corn and soybeans in many of the Midwest states. According to the USDA Crop Progress Report, corn development is delayed in all Midwest states compared to the 5-year average, with the greatest delay in Iowa, Illinois, and Kentucky (Figure 9). The percent of soybeans setting pods is behind the 5-year average by more than 15% in Iowa, Kentucky, and Wisconsin (Figure 10). Indiana is the only Midwest state with soybeans blooming and setting pods ahead of the 5-year average. Growing degree days since April 1st lag in the western Midwest by at least 150 days, with portions of Iowa, Minnesota, and Wisconsin behind by over 250 days (Figure 11). Growing degree days are slightly above normal in portions of the eastern Midwest.
Despite the delay in development so far this year, according to an article in the August 19th issue of FarmWeek, USDA's August crop production report confirmed that a bin-buster harvest is expected this fall for US corn and soybean growers. Across the Midwest, USDA projected crop yields range from 130 to 172 bushels per acre for corn, which is a significant increase from last year in most states. However, the article also states that many producers around the region are saying that more rainfall is needed to finish the crops this year.