Midwest Weekly Highlights - October 1-7, 2003

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Unseasonably cold weather brings an early end the growing season across much of the region.

The month of October got off to a chilly start as a series of cold fronts ushered increasingly colder air into the Midwest the last several days of September. A strong upper level low pressure system over southern Ontario (Figure 1, Unisys) pumped the cold air southward. By the morning of October 1 temperatures in the mid 20s were found as far south as central Iowa. As the high pressure system anchoring this cold air mass drifted over the central Midwest early on October 2 overnight low temperatures dropped into the mid and upper teens in Minnesota and northern Wisconsin (Figure 2, Unisys), and into the mid 20s as far south as central Illinois. Embarrass, MN reported the coldest temperature in the nation on October 2 with a reading of 13F. Freezing temperatures reached into southern Illinois and Indiana. By October 3 a significant portion of the Midwest had experienced freezing temperatures (Figure 3), and the northern half of the Midwest had experienced a hard freeze on at least two days. For many areas of the central Midwest the freezing temperatures occurred about two weeks earlier than normal.

The first significant snowfall of the season occurred in the Michigan Upper Peninsula and northern Wisconsin on October 1-2, with as much as 5 inches of snow being reported in the northern tier of Wisconsin counties.  Marquette, MI received 2.1 inches of snow on October 2, which set a new daily record. The previous record for October 2 was 0.7 inches, set in 1980. Cleveland, OH received 0.3 inches of snow on October 2, tying the record for the date of the earliest measurable snowfall. One tenth of an inch was recorded on October 2, 1974.

Temperatures the first several days of the week averaged 10 to 15 degrees below normal (Figure 4), but began to moderate the last half of the period. By October 7 maximum temperatures climbed to the mid and upper 70s across much of the region, even as far north as northern Minnesota. Nevertheless, temperatures for the week were well below normal across most of the Midwest. Average daily temperatures ranged from 10 degrees below normal from Michigan through northern Ohio to 2 degrees above normal in far western Minnesota (Figure 5).

Precipitation this week (Figure 6) was limited to the rain and snow accompanying the upper low on October 1 and October 3 in the northern Midwest, and to showers and some thundershowers that accompanied a weak cold frontal passage on October 3.  Except for some heavier precipitation in northern Michigan, most precipitation this week across the Midwest was light and scattered, providing favorable conditions for harvest activities. The scattered showers produced .25 inch or less, although a few areas received as much as .50 inch.