Midwest Weekly Highlights - January 11-17, 2011

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Cold Pattern Continues

This week was comparatively warmer than normal in the northern Midwest to much colder than normal across the southern two-thirds of the region. Temperatures ranged -10°F below normal from southwestern Iowa through western Missouri to 2°F to 3°F above normal from northeastern Minnesota across Wisconsin and the Michigan Upper Peninsula (Figure 1). The warmer weather in the northern Midwest was largely due to much above normal minimum temperatures during the period. Despite deep snow cover, minimum temperatures from northeastern Minnesota through the northern half of Wisconsin were from 5°F to 7°F above normal (Figure 2), while maximum temperatures were near to slightly below normal (Figure 3). The warmer than normal minimum temperatures were due to frequent overnight cloud cover associated with the weather systems moving through the Midwest. There were just a few temperature records set this period.
 

Wet North, Still Very Dry South

Precipitation was normal to well above normal north of a line from Kansas City, MO to Milwaukee, WI (Figure 4). Precipitation was noticeably lacking in the southern Midwest, with precipitation only 10 to 50 percent of normal. The January 11th U.S. Drought Monitor depicted little change in drought status across the Midwest, with Extreme Drought persisting in the Missouri bootheel (Figure 5). Most precipitation this week fell as snow. Snowfall was much above normal across the entire Midwest, except for extreme southern Missouri into western Kentucky (Figure 6). At the end of the week two or more inches of snow covered the ground generally from Interstate 70 northward, with one to two feet of snow on the ground across Minnesota and the northern two-thirds of Wisconsin (Figure 7).
 

Quick Hitters

A series of fast-moving low pressure systems brought snow to the Midwest this week. As the week began the first of these systems was beginning to affect the Midwest (Figure 8). It brought from two to nine inches of snow to the central Midwest over a two-day period (Figure 9). The snow was heaviest in western Iowa where accumulations of six to nine inches were common, with a few locations with as much as 11 inches. In the wake of this storm, northwesterly winds on the back side of the system produced lake-effect snow in Minnesota, Wisconsin, Michigan, Indiana, and Ohio.

On January 14th another low pressure system moved through Minnesota and northern Wisconsin (Figure 10) producing a swath of two to six inches of snow across most of Minnesota, Wisconsin, and Michigan (Figure 11). The last system of the week entered the region early on January 17th (Figure 12). Precipitation with this system fell mostly over Minnesota, Iowa, and Wisconsin, northern Illinois and Michigan,where generally two to three inches of snow accumulated (Figure 13). The snow continued through the day on January 17th, and 48-hour snowfall totals ending on the morning of January 18th totaled four to six inches from eastern Wisconsin through lower Michigan.
 

-SDH-
The Iowa State Climate Office also contributed to this report.

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