Midwest Overview - December 2009

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Temperature

December temperatures ranged from several degrees below normal along the western edge of the region to near normal in most of the Midwest. Temperatures ranged from 2°F to 6°F below normal in Missouri, Iowa, and southwest Minnesota while temperatures within 2°F of normal extended across most of the Midwest (Figure 1). Arctic air spread into the Midwest at the end of the month.
 

Precipitation

The heaviest precipitation fell along the southern edge of the Midwest in December. Precipitation totals exceeded 5 inches in southeast Missouri, southern Illinois, and southeast Kentucky (Figure 2). Because normal precipitation varies considerably during December, the picture looks very different when viewed as a percentage of normal precipitation. Most of lower Michigan, Indiana, Ohio, western and central Kentucky, and southern Missouri received between 75% and 125% of normal while precipitation totals exceeded 200% of normal in most of Iowa and Minnesota along with small parts of southwest Wisconsin, northwest Illinois, and northwest Missouri (Figure 3). Preliminary December numbers rank both Iowa and Minnesota as the second wettest and Wisconsin as 5th wettest on record. The wet weather has yet to alter the depiction in the US Drought Monitor (Figure 4) which continues to reflect long-term drought centered in northwest Wisconsin.
 

Major Snow Storms Hit the Midwest

In December, the Midwest and High Plains were directly hit by two major snow storms. Monthly snow totals topped 30 inches in northwest Iowa (Figure 5). Higher totals were recorded in Michigan along the Great Lakes where lake-effect snow added to the totals. Another system that socked the east coast with heavy snow also clipped eastern Kentucky.

Preliminary numbers show Iowa with it's second snowiest December, 22.2 inches, and the month tied for the second snowiest of any month in Iowa history (with February 1962). Both International Falls and Duluth, Minnesota ranked in the top ten for both precipitation and snowfall. Jackson, Kentucky had record December snowfall with 17.6 inches, easily topping the old record of 11.5 inches. It was also the fifth wettest December in Jackson.

The first snow storm (Figure 6), on the 8th-10th, was a blizzard which laid down a swath of snow, exceeding a foot in places (Figure 7), and brought strong winds across the Midwest. The Iowa statewide snowfall total of 10.2 inches ranked this storm as the third largest in history.

The second Midwest storm (Figure 8), over the Christmas holiday, again brought heavy snow and strong winds. This storm was slower moving and brought snow to more of the Midwest. The heaviest snow fell in northwest Iowa, and western Minnesota where snowfall totals exceeded a foot with totals over 20 inches along the Iowa-Minnesota border (Figure 9). Iowa statewide snowfall of 8.2 inches ranked this storm as the eighth largest in history. So two storms ranked in the top ten of Iowa history just weeks apart.

An east coast snow storm (Figure 10) dumped well over a foot of snow from the Carolinas to New England. Eastern Kentucky was on the west edge of the storm but Jackson still received just under a foot (11.6 inches) of snow in a 24-hour period ending on the 19th (Figure 11).
 

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