Midwest Weekly Highlights - December 1-7, 2013

---

Winter Storm Impacts Midwest, Brings Snow and Ice

The first week of December brought heavy snow and freezing rain to many parts of the Midwest. Many locations across the region were under winter storm warnings starting on December 5th, as a winter storm system made its way into the Midwest (Figure 1). There was a stationary front across the south which had a strong gradient between heavy snow in southern Missouri, southern Illinois, and southern Indiana (Figure 2) and freezing rain just south of the line in portions of the Missouri bootheel and Kentucky. Even though some areas experienced ice in the Midwest (Figure 3), the worst of the ice storm was in southern portions of the United States, mainly Texas, Arkansas, and Tennessee.

It was an active week in terms of snowfall for northern portions of the region. There was snow reported on every day of the week in the upper Midwest, with the heaviest snow amounts falling between December 1st through 4th (Figure 4). By the end of the week, the snow depths measured 12" to 18" across northern Minnesota and northwest Wisconsin (Figure 5). The highest weekly totals were reported in northern Minnesota along Lake Superior. A station in Two Harbors, MN (Lake County) reported the highest total of 35.3" throughout the duration of the storm. The heavy snow in northern Minnesota caused several school closings, including University of Minnesota Duluth, dozens of traffic accidents, large tree branches to break, large waves on Lake Superior which impacted shipping, cancellation of holiday events, and slowed traffic in the Twin Cities area. Minnesota Public Radio website posted a gallery of photos from this event. Several daily snowfall records were set throughout the week across the region, including a few monthly snow records.

As expected, the total snowfall for the week (Figure 6) was significantly above normal for portions of the upper and lower Midwest, including 8" to 10" above normal across southern Missouri, southern Illinois, and southern Indiana and 14" to 16" above normal in the Lake Superior region of Minnesota and Wisconsin (Figure 7). Total precipitation ranged from a high of 3" to 4" in eastern Kentucky to no precipitation in northern Missouri, southern Iowa, and western Illinois (Figure 8). These totals resulted in below normal precipitation across the central Midwest and above normal across much of the Ohio River Valley and upper Midwest (Figure 9).

Arctic Air Blasts Western and Upper Midwest

The storm system that brought the mix of winter precipitation also brought very chilly arctic air, with average minimum temperatures 20°F or less widespread across the western Midwest and into northern Michigan (Figure 10). Sub-zero temperatures made their way into the region during the second half of the week, with the lowest of temperatures dipping to -30°F in portions of northern Minnesota on the morning of December 7th (Figure 11). Many areas in Minnesota and Wisconsin did not get above 0°F on December 6th and 7th. While the chilly temperatures in the western Midwest were below normal, portions of the eastern Midwest were experiencing near to above normal temperatures (Figure 14). There were over 100 daily temperature records set throughout the week, a majority of which were record lows, but a few record highs as well from eastern half of the region.

-MW-