Above Normal Precipitation Across Six Midwest States
December precipitation ranged from a low of only 0.1" to 0.25" in western Iowa to 8" to 10" in portions of the Missouri bootheel and eastern Kentucky (Figure 1). Widespread monthly precipitation greater than 3" to 4" stretched across southeastern portions of the Midwest. The monthly totals resulted in below normal precipitation in Iowa, Missouri, the northern half of Illinois, and southern Wisconsin (Figure 2). Iowa only received 52% of normal precipitation, while Missouri and Illinois were both 85% of normal. The other six states in the Midwest were above normal for the month with Minnesota being the wettest compared to normal (165%). Throughout the month of December, there were just over 460 daily precipitation records set, 37 of which also set monthly precipitation records. A majority of the monthly records were set on December 22nd in Indiana, Missouri, and Ohio after a large winter storm system impacted the region (62% of the stations that broke a monthly precipitation record during this event had a period of record greater than 80 years).
Snowfall Near to Above Normal
December snowfall was above normal for much of the region, with largest departures in the northern half of the region (Figure 3). Northern Michigan received 20" to 25" above normal for this time of year, with northeastern Minnesota 15" to 20" above normal. The below normal departures were minimal, with most locations within 5" of normal. Monthly snowfall totals ranged from only 0.1" in southern Kentucky to over 50" in northern Michigan (Figure 4). The highest monthly totals were reported in the Upper Peninsula of Michigan, specifically in Greenland, MI (Ontonagon County) where 71.9" of snow fell during December. The snow across the region fell in several storms that moved across the Midwest during the month. The paths of the storms varied but the Upper Midwest was hit repeatedly. During the snowy month of December, there were over 545 daily snowfall records set, which were scattered throughout the month and across the region. A few of the snowfall events also set all-time snowfall records for stations in Illinois, Kentucky, and Wisconsin.
Below Normal Temperatures Throughout Majority of Midwest
December temperatures across the Midwest ranged from just above normal in Ohio and Kentucky to well below normal in Minnesota, particularly in northern Minnesota (Figure 5). Statewide values were +0.8°F above normal in Kentucky and +0.4°F above normal in Ohio while colder temperatures were recorded to the northwest with Minnesota (-7.9°F), Wisconsin (-6.5°F), Iowa (-5.3°F), and Michigan (-5°F) well below normal for the month. Minnesota had its 8th coldest December in 119 years of record while Wisconsin and Michigan each ranked as 11th coldest. Many northern Minnesota locations recorded their coldest December or were among the ten coldest.
Daily temperature records were mostly record lows in the region during December. Warm advection ahead of the stalled front on December 20th-22nd brought some record highs to Kentucky and Ohio but several systems dropped temperatures to record lows during the month.
Severe Weather Limited to One Day in December
Severe weather in December was limited to the 21st of the month in the Midwest. The couple hundred wind reports, mostly in Kentucky and Ohio, were reported along with three EF1 tornadoes in Kentucky. The tornadoes all damaged numerous trees along with roofs, barns, and other outbuildings. These severe weather reports were associated with a large storm event that moved through the region on December 20th and 21st. Read more about this system in the week 3 Climate Watch report.
Drought conditions on the U.S. Drought Monitor did not see much change in the Midwest throughout December (Figure 6). Despite above normal precipitation in six of the nine Midwest states, much of this precipitation fell in drought-free areas. The areas experiencing severe drought (central Iowa, western Wisconsin, and central Illinois), received below to near normal precipitation for the month.
2013 Annual Summary
Annual temperature values for 2013 were slightly cooler than normal for a majority of the region, with the exception of portions of Michigan, eastern Indiana, Ohio, and eastern Kentucky which were within a degree of normal (Figure 7). Statewide values range from just above normal in Ohio (+0.1°F) to the coldest departure values for the year in Minnesota (-1.8°F), Iowa (-1.3°F), and Wisconsin (-1.3°F).
Annual precipitation values for 2013 topped normal for all nine states using preliminary statewide estimates (Figure 8). Statewide annual values ranged from 104% of normal (Iowa) to 122% of normal (Michigan). Total annual precipitation ranged from a low of 20" to 30" in western Minnesota and western Iowa to 60" to 70" in extreme southern portions of the region (Figure 9).