November 2007
Midwest Overview - November 2007
The month of November lived up to its reputation as a transition month in the Midwest where the average daily temperatures see about a 10°F decline from the beginning to end of the month. The month started out rather mild but ended with a winter chill in the air.
The western portions of the region were relatively warmer than the eastern half. Average daily temperatures ranged from 2.5 °F above normal in western Minnesota to 1.5°F below normal in southern Kentucky and eastern Michigan (Figure 1). Across much of the central Midwest temperatures were close to normal. As might be expected during the fall season, there were several large temperature swings during the month. The first widespread hard freeze for most of the region came during the first week of the month, followed by a brief warm-up and then more cold weather. There was a larger west-to-east temperature difference during the first half of the month, with average daily temperatures running about 6°F above normal in northwestern Minnesota to 2°F below normal in the Ohio Valley (Figure 2). During the last two weeks of November, the temperature departure gradient was much less as temperatures were near to a little below normal over most of the region. The exception was in the Michigan Upper Peninsula where a developing snow cover helped keep the temperatures 5°F below normal (Figure 3). The first subzero temperatures of the season occurred the morning of November 27 across northern Minnesota with readings as low as -13°F.
Dry weather persisted in most of the region west of the Mississippi River, where November precipitation was less than 25 percent of normal, and as low as 5 to 10 percent of normal in northwestern Iowa and southwestern Minnesota (Figure 4). Parts of the Ohio Valley a4nd a band from east-central Illinois through the northern half of Ohio received normal to above normal precipitation. Heavy rainfall in Kentucky the second and fourth weeks of the month significantly reduced drought impacts in the southeastern portion of the state, and at the end of the month Extreme Drought existed in all or parts of only nine counties in Kentucky. November snowfall was generally below normal except in the lake efect areas in Minnesota and the Michigan UP (Figure 5).
Winter Arrives
Two storms during the last ten days of the month produced snow across the Midwest. The first hit the Wednesday before Thanksgiving, dropping snow on an area from Iowa through Michigan and complicating holiday related travel. On November 27 an intense low dropped into the northern United States and produced heavy snow in the lake effect areas of Minnesota, Wisconsin, and Michigan, The snow was accompanied by winds gusting to 74 mph, and trees and power lines were downed across the affected areas. Persistent northwesterly flow across the upper Midwest kept the lake-effect snow machine running through the end of the month. By the end of November up to 18 inches of snow were on the ground from the arrowhead of Minnesota across the Michigan UP (Figure 6).
-SDH-