Midwest Weekly Highlights - October 1-10, 2004

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Freezing Weather Arrives, Dry Weather Persists

A series of strong cold fronts plunging through the Midwest brought freezing temperatures to the region the first week of the month, ending the growing season for much of the region as far south as the Ohio River.  Temperatures for the first ten days of the month ranged from 1F to 2.5F below normal in a wide band from the northern half of Missouri eastward through Ohio (Figure 1).  Outside of this band, temperatures were generally near normal.  The exception was across northern Minnesota eastward across northern Wisconsin and northern Michigan where temperatures ranged from 1F to 3F above normal.

Rainfall continued to avoid a large portion of the central Midwest the first part of October (Figure 2).  Southeast of a line from near Saginaw, MI, to Chicago, to St. Louis, rainfall for the period October 1-10 was less than 50 percent of normal.  The driest area was along the Ohio River in northern Kentucky, southern Indiana, and southwestern Ohio where rainfall was less than 5 percent of normal.  Rainfall was near to above normal from west-central Missouri to eastern Iowa to central Wisconsin, where a cold front interacted with the moisture from the remnants of  Tropical Storm Matthew October 7-8 to bring rainfall amounts in excess of two inches to some locations.  Much of the Midwest has been very dry since September 1 (Figure 3), with precipitation less than 75 percent of normal.  Rainfall has been above normal across Minnesota and western Wisconsin during this period.  In addition, the series of tropical systems moving up through the eastern United States during September brought above normal rainfall to southeastern Ohio.  As of October 5, the U.S. Drought Monitor indicated one area of abnormally dry to moderate drought conditions across northern Illinois, much of Wisconsin, and most of Michigan, and another from southern Missouri through southern Indiana (Figure 4).  The dry weather was favorable for field work and agricultural producers made significant progress with the fall harvest.  However, the extremely dry conditions also accelerated drying of crops, and moisture levels of the corn in some areas were below optimal levels. In addition, the lack of rainfall created a fire hazard in the dry fields and contributed to numerous combine fires in Illinois and Indiana.


Early Freeze Ends Growing Season Across Much of the Midwest

A series of cold air outbreaks the first week of October brought near and subfreezing temperatures, ending the growing season across much of the region.  The first cold front entered the northern Midwest early on October 1, and by the morning of October 2 had moved through all but Kentucky and Ohio (Figure 5).  Freezing weather spread as far south as northern Missouri and as far east as  Iowa (Figure 6) as the next surge of cold air was already dropping south into Alberta and Saskatchewan.  On October 3 freezing weather was limited to central Illinois and western and central Indiana (Figure 7).  By sunrise on October 4 the next cold front had pushed almost to the Ohio River with subfreezing temperatures in the upper Midwest (Figure 8).  The core of the cold air settled over the central Midwest on October 5 (Figure 9).  Some locations tied or set new low temperature records during the week.  For much of the central Midwest, the first freeze was about ten days to two weeks earlier than normal.