December 22-31, 2001:

The final 10 days of the year, December 22-31, coincided with the very late onset of winter conditions in the Midwest. After temperatures were well above normal for all of November and the first 20 days of December, a blast of arctic air finally entered the region and persisted, resulting in temperatures ranging from near normal in the northern Midwest to 6-7°F below normal in the southern Midwest (Figure 17). Once the first cold front entered the region on the 22nd, a large trough set up over the Midwest, causing cool air to persist but not really bringing much precipitation to the majority of the Midwest (Figure 18). Most of the southern Midwest received less than 50% of normal precipitation for the week (Figure 19). This dryness was not entirely unwelcome, as some winter wheat growing areas in the southern Midwest were in poor condition due to previous heavy rains and saturated soils.

Warm temperatures in the early winter left the Great Lakes with little surface ice and tremendous stores of energy to fuel the lake-effect machine, creating ideal lake-effect snowfall conditions. The heaviest snowfall in the Midwest was concentrated on the southern and eastern shores of Lakes Superior, Michigan, and Erie; only a few inches of snow fell generally as upper level disturbances rotated around the upper level low north of the Great Lakes (Figure 20). The snowfall totals for individual locations depended on the day and wind direction; from December 24 to 29, at least one Midwestern observer station reported more than 10 inches of snow on each day. The 24th was the most important day at Marquette, MI (13 inches), downwind of Lake Superior, while the 26th had the largest snowfall total at Charlevoix, MI (15 inches), downwind of northern Lake Michigan. However, no single location received close to the enormous 81.5 inches of snowfall observed in Buffalo from December 24-28. The widespread lake-effect snowfall end on the 30th (Figure 21, NWS), with the last day of the year passing very quietly.