Cool in the East, Warm in the West

It seems that the Mississippi River acted as an unofficial boundary between cooler and warmer than normal temperatures for the week (Figure 1). A switch from zonal flow (east to west) to a ridge (warm air surging northward) and trough (cool air surging southward) pattern set up over the Midwest, resulting from upper-level low pressure systems. East of the Mississippi River, near normal to as much as 6.5°F below normal average temperatures were observed. In Patoka Lake, Indiana (Dubois County), average temperature was 37.4°F, which was 6.5°F below normal for the week. West of the Mississippi, temperatures were 2 to 8.1°F above normal. Sioux City, Iowa (Woodbury County) average temperature was 39.3°F, a whopping 8.1°F above normal.

Precipitation Below Normal

Much of the Midwest experienced slightly below normal precipitation for the week. Widespread 0.5 to 1.0” departures were seen through Missouri, Illinois, Wisconsin, Indiana, and Ohio (Figure 2). In southern Missouri and Kentucky, precipitation ranged from 1.0 to 1.5” below normal. Surface high pressure systems dominated the weather pattern for much of the week, except for a lone cold front partnered with unorganized precipitation through much of southern portions of the Midwest. Precipitation totals varied, but remained less than 0.75” over much of the Ohio River Valley (Figure 3). Abnormally dry (D0) conditions expanded through Iowa, Missouri, and Illinois on the November 30 U.S. Drought Monitor (Figure 4). Slight improvements in drought were seen in extreme northeast Minnesota. Precipiation totals were elevated over northeast Wisconsin and the entirety of Michigan, ranging from 0.75-1.75” (0.5 to 1” above normal) (Figure 2). Most of this precipitation fell as snow.

Above Normal Snowfall

Widespread snowfall ranging from 2 to 10”, with isolated locations exceeding two feet, were observed across northeast Wisconsin and the entirety of Michigan (Figures 5 and 6). Kalkaska, Michigan (Kalsaka County) received 24.3” of snow, which was 17.2” above normal for the week. Lake Michigan lake effect dropped up to 4” of snow in western Michigan November 25-26. Two systems dropped up to 4.5” of snow in Michigan from November 27-28. An Alberta Clipper dropped an additional 2-4" of snow across Michigan overnight November 29-30.