Midwest Overview - December 2007

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Cold and Snow Northwest, Milder and Wet Southeast

December was a cold and snowy month across the northwestern half of the region, generally north of a Springfield, MO to St. Louis to Chicago to Detroit line. Temperatures in the northwestern half of the Midwest ranged from 4°F below normal in western Iowa to near normal in eastern Michigan (Figure 1). In the southeastern half of the Midwest, temperatures ranged from 1°F above normal in southeastern Missouri to 4°F in southeastern Kentucky.

December was a wet month across all but a few isolated areas of the Midwest (Figure 2). Precipitation was heaviest in Minnesota, Iowa, and Wisconsin, as well as along the Ohio River. The only areas with slightly below normal precipitation were portions of southern lower Michigan and extreme southeastern Kentucky.

The entire Midwest received some measurable snow during December (Figure 3), and snowfall was above normal across the entire region except for the extreme south (Figure 4). On December 15 snow covered the Midwest to south of the Ohio River in the wake of a series of storms (Figure 5).

 

Consecutive Ice Storms Glaze Central Midwest

The weather pattern over the Midwest favored a storm track that brought low pressure systems through the Midwest every few days, and the timing was such that major storms hit some portion to the Midwest every weekend during the month. For the second year in a row a major winter storm struck the Midwest on December 1. This year, as with last, the storm brought a mix of freezing rain and snow to the region, followed by an Arctic outbreak by the end the first week. The second weekend of December saw the start of three to four days of freezing rain across the central Midwest, which encased parts of Missouri, Iowa, and Illinois in 0.75 to 1.5 inches of ice (Figure 6). Power was still out for thousands of customers in Missouri when another winter storm took aim on the region the third weekend of the month. By the morning of Sunday, December 16, a blanket of snow covered the Midwest to the Ohio River, and strong gusty winds hampered travel.

The southern portions of the Midwest got a reprieve from the winter weather the fourth weekend of December, but the storm track, which had shifted a little further north and west, brought heavy snow to the upper Midwest and Great Lakes while light rain fell to the south and east of the low pressure system. In the wake of this deepening storm winds gusting to 60 to 70 mph caused power outages in Wisconsin, Illinois, Michigan, Indiana, and Ohio.

Two storms affected the Midwest at end of the month bringing significant snow to Iowa, Illinois, Wisconsin, Indiana, and Michigan. On December 31 four or more inches of snow blanketed the ground from Kansas City to Chicago to Detroit (Figure 7), while areas to the south and east were generally snow free.

 

-SDH-