North/South Temperature Divide
Temperatures were divided with cooler than normal temperatures to the north, and warmer than normal in southern Missouri and Kentucky
(Figure 1). Most of northern Minnesota, northern Wisconsin and the U.P. of Michigan were 4-6°F below normal. Average temperatures in southern Wisconsin, southern Minnesota, Lower Michigan, northern Illinois and northern Indiana were all 2-5°F below normal. Maximum temperatures were even cooler in these areas at 5-9°F below normal (Figure 2). Dozens of daily low maximum temperatures were recorded broken as a result
(Figure 3). Areas in southern Missouri were 3-5°F above normal while parts of Kentucky were 1-2°F above normal.
Fairly Dry for Most
Precipitation amounts were lower across a large portion of the Midwest, with the only heavy rainfall across the northern reaches of the region (Figure 4). Most of Missouri, Iowa, Indiana and southern Lower Michigan had less than half the normal amount for the period
(Figure 5). However, amounts over 1.5 inches in northern Wisconsin, Minnesota, northern Illinois, and the western U.P. of Michigan led to amounts 150-175 percent of normal. More than two dozen daily precipitation records were broken from heavy rain (Figure 6).
Drought across the Midwest doubled in area from 2.5 percent to 5 percent according to the September 3 U.S. Drought Monitor
(Figure 7). Most of this expansion occurred in northern Lower Michigan with areas in central Iowa and northern Indiana as well. A drier summer and continued dry weather into the early fall contributed to the expansion. More than 2 million people were estimated to be in drought-affected areas.
Some Severe Storms
Several severe thunderstorms impacted the upper Midwest during the period (Figure 8). Most of these storms occurred on September 2 (Figure 9) and September 9 (Figure 10), bringing damaging wind gusts. Brief tornadoes were also reported in Minnesota on September 2.