Midwest Weekly Highlights - December 11-17, 2018

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Winter Warmth

After a cold stretch that lasted from mid-October through first week of December, warm weather returned to the Midwest during the week (Figure 1).  Temperatures were above normal across the entire Midwest, with most of the region 4-6°F above normal.  Northwestern Minnesota was more than 10°F above normal. Maximum temperatures averaged above freezing for most of the region (Figure 2).  Coupled with sunny skies, the snowpack over the Upper Midwest decreased during the period (Figure 3).  More than a dozen daily high maximum and minimum temperatures were broken from the warmth (Figure 4).
 

Stormy to the South

Drier weather was common across the Upper Midwest and central Midwest, while moderate to heavy rain fell across the Ohio River Valley and southeastern Missouri (Figure 5).  Very little to no precipitation fell in Iowa, Wisconsin and most of Minnesota, where less than a tenth of an inch of precipitation was recorded.  Amounts were much heavier in southern Illinois, southeastern Missouri and southwestern Indiana, with recorded values of 2-3 inches.  Most of this precipitation fell from a storm that moved through the area through the mornings of December 14 (Figure 6), December 15 (Figure 7) and December 16 (Figure 8).  In many of these areas, more than twice the normal amount of precipitation fell (Figure 9).  Some of the heaviest amounts for the week included 3.78 inches near Kaskaskia, IL (Randolph County), 3.54 inches in Mount Vernon, IN (Posey County) and 2.96 inches in Desoto, MO (Jefferson County). 

Snow was limited due to warmer temperatures in the region (Figure 10).  Areas in northwestern Minnesota received more than three inches, with most of it falling through the morning of December 12 (Figure 11).  Parts of Wisconsin also received 1-2 inches, with most of the snow falling through the morning of December 13 (Figure 12).
 

Moderate Drought Introduced in Missouri

After just over a month of drought-free conditions in the Midwest, moderate drought was introduced into several counties in southwestern Missouri in the December 11 U.S. Drought Monitor (Figure 13).  Factors cited for the introduction of drought included short- and long-term deficits in precipitation and poor groundwater conditions.  However, 98 percent of the region remained free from abnormally dry or drought conditions.
 

-BJP-