November 24-30, 2007
Midwest Weekly Highlights - November 24-30, 2007
A Quiet End to November
The last week of November was generally uneventful across the Midwest. Temperatures this week were near to below normal across the northwest half of the region, and well below normal over the southeast half. Average daily temperatures ranged from 1°F below normal in southern Minnesota south through northern Missouri to more than 8 °F below normal across far northern Minnesota (Figure 1). The first subzero readings of the season occurred this week over snow covered ground in northern Minnesota.
Precipitation this week was confined to the southeastern third of the region and around the Great Lakes. The eastern half of Ohio and much of eastern Kentucky received normal to well above normal precipitation, while southern Minnesota and northern Iowa recorded no measurable precipitation (Figure 2). The only significant change in the U.S. Drought Monitor for the Midwest this week was a reduction in the area of Extreme Drought in southeastern Kentucky (Figure 3), which now encompasses all or parts of only nine counties. As recently as mid-October the entire state of Kentucky was in Extreme Drought.
Heavy snow fell in the lake-effect areas around Lake Superior and Lake Michigan, with more than a foot and a half of snow in some locations this week (Figure 4). At the end of the month snow cover extended from the northern half of Minnesota across the northern third of Wisconsin, the Michigan Upper Peninsula, and much of southern lower Michigan (Figure 5).
Storm Brings Rain to Southern Midwest
A low pressure system developing over the northern Gulf of Mexico on November 25 moved northeast into the lower Ohio Valley by the morning of November 26 (Figure 6). A shield of rain spread northward from Kentucky through Missouri, Illinois, Indiana, and Ohio. Rainfall amounts in Kentucky ranged from 1.25 to 2.00 inches and in Ohio amounts ranged from 1.00 to 1.25 inches. Rainfall amounts tapered off rapidly to the north, with only a few hundredths falling in northern Illinois.
Heavy Snow and Whiteout Conditions
The Ohio Valley low raced northeastward and was over Maine by November 27. Back to the west, an intense, compact low dropped out of Canada and was over Lake Superior (Figure 7). This storm produced periods of very heavy snow and high winds as it moved over the northern Great Lakes. Snowfall rates of up to four inches per hour and winds gusting from 50 to 70 mph caused whiteout conditions and caused widespread tree damage. In Baraga County, MI, the U.S. Forest Service reported that a 32 inch diameter hemlock tree was snapped in half, and white pines to 2 feet in diameter were snapped off at the base by the high winds. Wind gusts to 69 mph toppled trees along a 16 mile stretch of road in Alger County, MI. A wind gust of 74 mph was recorded at the Stannard Rock Lighthouse located 28 miles east-southeast of Keweenaw Point.
Very cold air knifed into the northern Midwest behind this intense low, and the coldest temperatures of the season were reported over the snow-covered ground across the northern half of Minnesota. Subzero temperatures were recorded from North Dakota across the northern half of Minnesota (Figure 8). Both Warroad and Camp Norris, MN (Roseau County) reported low temperatures of -13°F on the morning of November 27. Subzero readings occurred again on the mornings of November 29 and 30.
Lake Effect Snow Continues
Snow continued to fall the rest of the week in the Keweenaw Peninsula of Michigan as cold air streamed across the relatively warm waters of Lake Superior. Snow was falling at the rate of one half to one inch per hour in some locations. Twenty-four snowfall totals ending on the morning of November 30 ranged from 9 to 12 inches, and much of the area had 12 to 18 inches of snow on the ground with snow continuing to fall.
Another Storm Looms
Another low pressure system was pushing onto the west coast on the morning of November 30. This storm was expected to organize and intensify over the Central Plains over the next 24 hours, and a variety of winter storm watches and warnings were issued for the northern half of the Midwest as the month came to a close (Figure 9).
SDH