September 1-4, 2001:

The period of September 1 to 4 was quite tranquil weatherwise in the Midwest. While August rushed out in a stormy manner, the first four days of September were dominated by high pressure from Canada (Figure 6, UIUC Dept. of Atmospheric Science). Temperatures were cooler than normal over the northeastern half of the region (Figure 7), and precipitation was limited to the tail end of the major frontal passage through Ohio and Kentucky, and the effect of weak frontal precipitation on the 3rd in Michigan and northern Illinois/southern Wisconsin (Figure 8). No appreciable severe weather took place in the Midwest during the period. Despite the isolated heavy rain at the end of August, the end of August through September 4th was quite dry over most of the region, and the dryness has increased in the Great Plains, Iowa, southwestern Minnesota, and northwestern Illinois (Figure 9, National Drought Mitigation Center). Most Midwest states had modest changes in topsoil moisture ratings of short / very short, with the exception of a large decrease in Minnesota (-18%) due to timely rains in the driest central area of the state, and large increases in Michigan (+15%), South Dakota (+14%), and North Dakota (+18%). The soil moisture levels in the Great Plains states were responding not only to dry conditions, but also to temperatures well above normal late in the period.