Midwest Weekly Highlights - September 8-14, 2010

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A Cool Start to September

Cooler than normal weather continued through the second week of September across the Midwest. Temperature departures ranged from near normal in western Missouri and Iowa to 5 °F below normal in parts of eastern Wisconsin and in lower Michigan (Figure 1). There were daily temperature records the first five days of this week, mostly record minimum and record low maximum temperatures.

Rainfall was heaviest in the far western and southern portions of the region, generally along the boundary separating the cooler, drier air from the warmer air to the south. Precipitation was more than two times normal in western Minnesota, northwestern Iowa, and Missouri eastward into Kentucky (Figure 2). Rainfall in far southern Missouri and northwestern Minnesota was four to five times normal. In contrast, rainfall was less the 50 percent of normal from eastern Minnesota southeastward into Ohio. Changes to the September14 U.S. Drought Monitor from the previous week were minor, with decreased dryness in central Illinois and some increase in parts of Indiana and Ohio (Figure 3).

The dry weather in the eastern half of the region allowed harvesting of corn and soybeans to continue ahead of pace. Corn harvest in Illinois was 18 percent complete as of September 14, compared to a 5-year average of 6 percent; in Indiana, 13 percent complete compared to a 5-year average of 2 percent; and in Kentucky it was 54 percent complete, compared to a 5-year average of 19 percent.
 

Heavy Rain and Spotty Severe Weather

A cold front that moved through the Midwest at the beginning of the period began retuning northward as a warm front as low pressure developed in Kansas (Figure 4). A complex of thunderstorms developed across southern and central Missouri beginning late on September 9 (Figure 5) and continuing through September 10 (Figure 6) dropping heavy rain for the second week in a row. Two to three inches of rain produced flash flooding across in (Benton and Morgan Counties) in Missouri on September 11. Severe weather was also reported, mostly high winds. As the system continued eastward on September 11 severe storms were reported in the eastern half of Kentucky.

-SDH-