November 14-20, 2001:

The period of November 14-20 was dry and very warm in the Midwest. Total precipitation was less than one inch in almost all of the Midwest (Figure 14), with the exception of some locations near the Great Lakes and in southwestern Missouri. Most of the Midwest received precipitation amounts well below normal (Figure 15). Only two weak low pressure systems traversed the region during the period, one affecting the lower Great Lakes on the 14th and 15th, and the other dragging a cold front through much of the Midwest on the 19th, with widespread light rain. The temperatures during the week were 8 to 16°F above normal in most of the Midwest, with larger anomalies in the northwestern Midwest and smaller anomalies in the southeastern Midwest (Figure 16). The "heat wave" was caused by the development of an unseasonably strong upper level ridge over the Midwest, with mid-tropospheric geopotential height anomalies more than 200 gpm above normal (Figure 17, Climate Diagnostics Center). Many high temperature records were set, including at Des Moines, IA, on the 16th, Lincoln and Springfield, IL, on the 17th, and Marquette, MI, and International Falls, MN, on the 18th. At Marquette, November 18 is now the latest date during the year in the station's history for the occurrence of a temperature greater than 60°F. The lack of rain and warm temperatures continued a pattern from earlier in November, so abnormally dry conditions continued to spread across both the western and far eastern portions of the Midwest (Figure 18, U.S. Drought Mitigation Center). A combination of dry conditions, heavy fuels, and arsonists caused 96,600 acres to burn in Kentucky during the first few weeks of November, with some smoke plumes big enough to be seen in satellite imagery (Figure 19, NOAA). Fortunately, a cooler air mass entered the region at the end of the period, and increased opportunities for precipitation are seen for the next period.