Midwest Weekly Highlights - December 11-17, 2012

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Precipitation Above Normal in Northwest Portions of Midwest

Accumulated precipitation during the week ranged from no precipitation in northwest Minnesota to 1" to 1.5" in Upper Michigan and eastern Ohio (Figure 1). Much of the region received at least 0.3" during the week. These totals resulted in precipitation that was below normal in the southeast portions of the Midwest and above normal in the northwest (Figure 2). Some areas in Minnesota and Iowa received more than twice normal precipitation. There were several daily precipitation records set throughout the week, mainly occurring on December 15th and 16th.

Portions of northern Minnesota and Upper Michigan received over 3" of snowfall during the week (Figure 3). For locations in Minnesota, this snowfall was above normal for this time of year. However in Upper Michigan, snowfall was still below normal (Figure 4). With little to no snowfall in other areas of the Midwest, several other locations in the region were also below their average snowfall for this time of year. By the end of the week, snow depth was greatest in Minnesota, with at least 4" reported on the ground across a significant portion of the state (Figure 5). A handful of daily snowfall records were set throughout the week.

Above Normal Temperatures Continue

While not as extreme as the first 10 days of December, average temperatures continued to run above average over the last week (Figure 6). The highest departures of 9°F to 10°F were in northern Illinois and east central Iowa. Central Minnesota was the only region to experience near normal temperatures throughout the week. Average maximum temperatures were significantly above normal in Iowa, with departures of 10°F to 12°F throughout most of the state (Figure 7). On the other hand, average minimum temperatures were not quite as extreme, with some areas in central Minnesota, southern Missouri, and southern Kentucky experiencing near to below normal minimum temperatures throughout the week (Figure 8).

There were just over 200 daily temperature records set throughout the week, with almost all of those being record highs and set sometime between the 15th and 17th. The number of records set during this past week is much less than the number set during the first 10 days of the month (Figure 9).
 

Drought Conditions

While the impacts of drought are less obvious in the winter months, drought conditions are still widespread throughout the Midwest after a very dry summer. According to the December 11th US Drought Monitor, almost 55% of the region remains at some level of drought (Figure 10). Extreme drought (D3) is the highest level of drought in the region at this time and is impacting a good portion of Iowa and southern Minnesota. According to the US Geological Survey, streamflow across the Midwest is below normal, especially in the southern Lake Michigan region, Iowa, and portions of Missouri (Figure 11).

-MW-