December 22-31, 2007
Midwest Weekly Highlights - December 22-31, 2007
Milder, with Heavy Snow in Upper Midwest
The last ten days of December were decidedly milder across most of the Midwest. Temperatures were 2°F to 4°F below normal in the far western portions of the region, but 2°F to 6°F above normal across the eastern two-thirds of the Midwest (Figure 1). Temperature departures reached 8°F above normal in portions of northern Minnesota, northern Wisconsin, and northern Michigan.
After three weeks of relatively wet weather, much of the region received only 50 to 75 percent of normal precipitation the last ten days of the month (Figure 2). The exception was a band from northwestern Missouri northeastward through Wisconsin and the Great Lakes which received from 200 to 400 percent of normal precipitation. This was largely the result of two major storms that moved through the region. Most of the precipitation fell as snow (Figure 3), with the heaviest amounts downwind of Lakes Superior and Michigan. There was little change in the U.S. Drought Monitor status this week in the Midwest, with small isolated areas of Moderate Drought and persistent Extreme Drought in extreme southeastern Kentucky (Figure 4).
Pre-Christmas Storm
Snow developed across the northern Midwest on December 22 as low pressure developed in northern Texas along a frontal system stalled out over the western Midwest (Figure 5). This low rapidly developed as it moved to the northeast along the front, and by the morning of December 23 it was producing heavy snow across Minnesota, Wisconsin, and Michigan, and high winds to much of the northern half of the region (Figure 6). By Christmas Eve morning up to 21 inches of snow had piled up along the southern shore of Lake Superior, with a foot or more of snow across the Arrowhead of Minnesota and northwestern Wisconsin (Figure 7). As the low intensified late on December 23 and early on December 24 winds increased and were gusting 50 to 60 mph across Wisconsin, Michigan, and the northern halves of Illinois Indiana, and Ohio. The National Weather Service reported a gust to 88 mph over Lake Michigan. The winds uprooted trees and knocked out power to 186,00 customers in Michigan, 24,000 in Illinois, and 11,000 customers in Wisconsin. Scattered power outages were also reported in Ohio as the high winds snapped power poles. The high winds caused more than 1150 flight cancellations at Chicago's O'Hare International Airport.
Once this storm departed the region, quiet weather settled in over the Midwest. A white Christmas was experienced only over the northwestern half of the region (Figure 8), and it was a mild day with high temperatures pushing into the 40s over snow-free portions of the Midwest (Figure 9). In Illinois, the milder weather caused ice to break apart resulting in ice jams along the Rock River. The river rose to 8.4 inches short of flood stage near Moline, IL (Rock Island County) on December 29. In Ohio, heavy rain and snow melt caused the Tiffin River near Stryker, OH (Williams County) to crest about 16 inches above flood stage.
More Winter for Northern Midwest
A second storm developing over the southern Plains on December 28 (Figure 10) headed northeast and brought more snow to an area from northern Missouri through Wisconsin, northern Illinois and Michigan (Figure 11). The heavy, wet snow hampered travel, with 60 to 70 percent of flights at Milwaukee's Mitchell International Airport delayed or cancelled on December 28.
Old Man Winter took another swipe at the Midwest as December and 2007 drew to a close. On December 31 a developing low over western Missouri moved east-northeast during the day, spreading precipitation through the northern two-thirds of the Midwest. South and east of the low center, much of the precipitation fell as rain, but heavy snow piled up from central Illinois to southeastern Michigan (Figure 12). A foot of snow piled up in the Detroit area putting a damper of New Year's Eve celebrations. Capac, MI (St. Clair County) reported 16 inches of snow from the storm, and 15 inches was reported just north of Clarkston, MI (Oakland County). The heavy, wet snow combined with winds of 30-35 mph caused scattered power outages and brought down tree limbs in southeastern Michigan.
SDH