December 2016 Weather and Its Impacts on Missouri

Pat Guinan
State Climatologist
Commercial Agriculture/University of Missouri Extension

A weather pattern change in early December ended the unseasonably mild weather that dominated during autumn. Modified arctic air masses settled into the region during the second and third week of the month and brought some of the coldest temperatures of the year to the state, most notably across northern sections on Dec 18-19, Table 1. Temperatures in Missouri were averaging 5-7 degrees below normal during the first 3 weeks of December, but unusually mild weather returned for the last 10 days of the year, Figure 1.

December 2016 Minimum Daily Temperature
Location*	County	Min Temp (°F)	Date
Albany	Gentry	-16	18
Grant City 5WSW	Worth	-16	18
Bethany	Harrison	-14	19
Princeton	Mercer	-14	19
Spickard 7W	Grundy	-14	19
Unionville	Putnam	-14	18
* NWS Cooperative network and Missouri Mesonet
Table 1.

Preliminary data indicate the average statewide temperature for December was 32.1°F, nearly 1 degree below normal, and much cooler than the record warmth set in 2015, Figure 2. It was the second month in 2016 to average cooler than normal, Figure 3. The string of warm months in 2016 made it the 3rd warmest year on record for the Show Me State, Figure 4. Only 1921 and 2012 were warmer.

With the exception of the Missouri Bootheel, below normal precipitation impacted Missouri during December. The statewide average total for the month was 1.37 inches, slightly less than 1-inch below average. The month was notably drier than December 2015 when Missouri reported widespread flooding and its 2nd wettest December on record, Figure 5. Heaviest monthly precipitation was confined to far southeastern sections where 3-5 inches were common. Much of the rest of the state reported between 0.5-1.5 inches.

Missouri experienced its third consecutive drier than average month, Figure 6, and as of December 27, 2016, the Drought Monitor map showed most of the state experiencing abnormally dry conditions, Figure 7. A few counties in southern Missouri were in moderate drought.

The cold weather during the first few weeks of December translated to higher than usual energy consumption and stressful conditions for outdoor workers, exposed livestock and pets. Some ranchers dealt with chopping ice for livestock due to frozen ponds. The period of cold weather also contributed toward an unusually early and persistent frost line in the soil for much of December prior to Christmas, especially over the northern half of the state.

No major winter storms impacted Missouri during the month, but a freezing drizzle event on December 16 quickly resulted in extremely hazardous conditions across parts of the state. With temperatures in the 20's and surfaces below freezing, a thin glaze of ice rapidly developed over roadways and sidewalks during the mid-morning hours. Conditions quickly became hazardous for traffic and pedestrians. Traffic along Interstate 70 between St. Louis and Columbia came to a standstill when portions of the interstate were shut down in both directions due to icy roads and vehicular accidents. The Missouri Highway Patrol reported more than 1,500 car crashes on Dec 16-17. Seven people were killed and 171 were injured. Hundreds of airline flights were cancelled at St. Louis Lambert International Airport. Local hospitals had a spike in slip and fall injuries and auto body shops were booked for repairs weeks in advance.

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Source: Pat Guinan, 573-882-5908