Midwest Weekly Highlights - December 18-24, 2017

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Heavy Precipitation in the South

Drier conditions were prevalent across most of the Midwest, except in the southern third of the region where it was very wet (Figure 1).  More than an inch of precipitation fell in the Ohio River Valley, with areas in southeastern Kentucky receiving more than three inches.  In many cases, this was more than twice the normal amount (Figure 2).  More than 50 daily precipitation records were broken (Figure 3). Most of these records occurred through the morning of December 23 (Figure 4).

Snowfall was common across the northern third of the region (Figure 5).  More than five inches fell in parts of northern Minnesota and the U.P. of Michigan.  This was more than twice the normal amount in northern Minnesota, but was less than normal in Michigan (Figure 6).  A system that began on December 22 also brought the first major snowfall to the central and southern Midwest.
 

December 22-25 Winter Storm

The first major winter storm of the season for central and southern parts of the Midwest brought 1-5 inches of snow to portions of Missouri, southern Iowa, central Illinois, northern Indiana and northern Ohio (Figure 7).  As the system gathered strength, up to an inch of snow fell along a line from southwestern Missouri through northwestern Ohio through the morning of December 23 (Figure 8).  The system gained further strength through the morning of December 24, where 3-5 inches fell in southern Iowa and northern Missouri (Figure 9).  Through the morning of December 25, 2-5 inches fell across northern parts of Illinois, Indiana and Ohio, as well as most of Lower Michigan (Figure 10).  Prior to this storm, many of these areas had received less than an inch of snowfall for the season (Figure 11).
 

Very Warm

Temperatures were above normal across most of the Midwest during the period (Figure 12).  Missouri, Illinois, Indiana, Kentucky and Ohio were all 6-10°F above normal.  Iowa, southern Minnesota, Wisconsin and Lower Michigan were mostly 3-7°F above normal. Northern Minnesota and the U.P. of Michigan were the only areas in the region near- to slightly below-normal. Minimum temperatures were a major driver for the above-normal temperatures, as most of Missouri, Illinois, Indiana and Kentucky were 10°F or more above normal (Figure 13).  More than 80 daily high minimum temperature records were broken or tied during the period (Figure 14).
 

-BJP-