Midwest Weekly Highlights - December 1-7, 2010

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A Wet or Dry Week? Depends Where You Were

Precipitation varied widely across the Midwest during the first week of December. Total precipitation varied from nothing for most of Missouri to more than two inches along the eastern edge of the region (Figure 1). Three different areas picked up more two to three times their normal for the week while the remaining areas were well below normal (Figure 2).

Most of the week's precipitation for the eastern parts of Ohio and Kentucky was reported on the morning of the 1st as the previous week's system moved off to the east (Figure 3). A narrow swath from southern Minnesota to southern Indiana picked up its precipitation in the form of snow on the 4th and 5th (Figure 4). Two-day snowfall totals exceeded 10 inches in Minnesota and 8-10 inches into central Illinois. The Upper Peninsula of Michigan accumulated its totals from an extended period of lake-effect snow. Dozens of daily precipitation records were set on the 1st and 4th and more than 100 daily snowfall records were also set on the 4th.
 

Cold Start in December

Temperatures steadily dropped throughout the week. Maximum temperatures dropped from the 30s to 50s on November 30th (Figure 5) to mostly 10s and 20s by December 7th (Figure 6). Mean temperatures for the week averaged below normal across the region. The upper Midwest was 1°F to 3°F below normal while temperatures ranging from 9°F to 13°F stretched from southern Minnesota to Kentucky and southern Ohio (Figure 7).

The snow cover played a role where the temperatures were the coldest (Figure 8). For example, the minimum temperatures on the 6th were coldest (Figure 9) where the snow depths were more than a couple inches (Figure 10). Maximum temperatures averaged even colder during the week, ranging from 5°F to nearly 20°F below normal in eastern Kentucky (Figure 11). Most of the daily temperature records set were record low maximum temperatures.
 

Drought Lingers in Missouri Boot Heel

Despite marked improvements in drought conditions to the east, the Missouri boot heel remained in the Extreme Drought category (Figure 12). Severe Drought conditions extended from southeast Missouri into western Kentucky. Pockets of Moderate Drought also lingered in Indiana and northeast Minnesota.
 

Winter Storm

The location of the winter storm that dropped several inches of snow from Minnesota to Kentucky was predicted well as the impacted areas were under Winter Storm Warnings or Winter Weather Advisories (Figure 13). The amounts of snow that fell were higher than expected however. Travel was impacted as numerous accidents were reported in Minnesota and Wisconsin and as airports in Minneapolis and Chicago delayed or cancelled hundreds of flights.
 

Ice Jams Cause Rapid but Minor Flooding on Minnesota Rivers

Early in the week, the Red River rapidly rose above flood stage in Wilken County, Minnesota due to ice jams. Late in the week, ice jams were suspected to be the cause of localized and unpredictable flooding near Fort Ripley, Minnesota (Morrison and Crow Wing Counties).
 

-MST-