Midwest Weekly Highlights - December 22-31, 2008

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Active End to December

The active weather pattern continued across the Midwest during the last ten days of the month, bringing precipitation to some part of the region each day during the period.  The strongest of these storms crossed the Midwest December 27 and 28.  While some snow did fall across Minnesota and Wisconsin with the system, the major story was the heavy rains across the southern portion of the region.  The daily onslaught of precipitation resulted in some parts of the Midwest receiving as much as 300% to 500% of normal during the period (Figure 1). The only area with below normal precipitation was across western Iowa, where as little as 25% of normal was received.  The December 30 Midwest Drought Monitor showed little change from the previous week despite the heavy rain across the southern portion of the Midwest (Figure 2). Severe (D2) drought persisted across central Kentucky and central Wisconsin. 

Temperatures varied greatly across the region (Figure 3). The southern and eastern portions of the region were as much as 6°F above normal, mostly due to unseasonably warm temperature ahead of the December 27-28 storm.  The northwest third of the region saw temperatures as much as 8°F below normal. 

December 27-28 Storm

A deep upper level trough and low pressure moved from southeast Colorado on December 27 to the Great Lakes on December 28 bringing precipitation to much of the Midwest (Figure 4). Ahead of the surface front, high temperatures surged in to the 60°F to 70°F range across much of Missouri, Illinois, Indiana, Ohio and Kentucky (Figure 5). As the surface cold front crossed the region the warm and moist air was lifted, resulting in showers and thunderstorms.  More than an inch of rain fell across most of Missouri and parts of Illinois (Figure 6).

AB