After a chilly November with multiple rounds of snow across the Midwest, winter largely backed off for most of December. It was a mild and wet first month of meteorological winter, with all major cities finishing well-above normal in the temperature department and also wetter than average.
The warm spot was Dayton, coming in at 5.6 degrees above average for December. Chicago was a close second, at 5.5 degrees warmer than usual. Columbus was the relative “cold” spot at only 3.8 degrees above average, with Indianapolis and Cincinnati coming in at 4.9 and 4.4 degrees warmer than normal respectively. Everyone was also wetter than average, with Cincinnati coming in at 2.19” more precipitation than normal. Columbus and Indianapolis were closest to normal, 0.60 and 0.62” above respectively, with Chicago finishing December at 1.07” more precipitation than normal and Dayton 1.51” above.
Despite the wet conditions, snowfall was rather sparse across the Midwest in December. Chicago and Dayton tied for “snowiest” sites in December at 1.4” (both several inches below normal). The least snowy was Columbus, at a paltry 0.4” of snow. Cincinnati and Indianapolis weren’t much snowier, both coming in with 0.5” of snow in December. All of these values are several inches below the usual snowfall for the month of December.
Radar imagery (courtesy of College of Dupage) showing heavy rainfall on December 1st
As the mild temperatures and monthly snowfall totals would suggest, there were a lot of rainy storms across the Midwest. We started off quickly December 1st and 2nd as low pressure tracked through the Great Lakes, bringing record daily rainfall to Cincinnati on December 1st (1.84”). Dayton also saw record rainfall of 1.11” on the 1st. Everyone saw close to or over 1.00” of rain to start the month with that storm. That system also brought a warm shot of air, with much of Ohio breaking into the 60s December 1st or 2nd. Indianapolis also topped out at 58, while Chicago was held in the 40s.
It briefly turned wintry later that week as snow showers affected the region December 4th and 5th and temperatures dropped to around 10 degrees below normal (highs struggling into the lower 30s, lows in the 10s/20s for several days). The “largest” snowfall out of that stretch was 1.0” of snow falling on Dayton during the early morning December 5th, with everyone else seeing snowfall amounts of less than half an inch. A cold front pushed through on December 6th bringing more widespread snow to central Indiana and central and southern Ohio, though again, amounts were very modest at a trace to locally 1” north of I-70 in Indiana and Ohio. Chicago missed the snow from the cold front and remained dry.
Temperatures warmed above normal towards the middle of December as another rainy low pressure tracked across the Ohio Valley between December 14th and 16th. Parts of Ohio saw rainfall amounts nearing 1” from that storm, with Indianapolis and Chicago seeing lighter amounts.
It remained generally mild through Christmas, hampering White Christmas chances for the vast majority of the region. Parts of Chicago did see a little bit of light wintry precipitation very early Christmas morning, but it was too light to make things “white.” Meanwhile, Indianapolis saw a cold rain, while Columbus and Cincinnati simply stayed dry. The exception was a narrow band of snow that developed Christmas morning over Dayton. This band missed Dayton International Airport due to its localized nature, though downtown Dayton was affected by between 0.5” and 1.0” of snow, bringing a white Christmas to a few lucky locales.
Surface analysis and satellite showing a low pressure with copious amounts of moisture affecting the Midwest December 31st
After freezing drizzle hit parts of Illinois and northern Indiana with slick travel on December 28th-29th the month ended, fittingly, with another warm low pressure tracking into the southern Great Lakes and bringing more moderate rain to parts of the region. Columbus and Dayton both recorded record daily rainfall on December 31st (1.01” and 1.47” respectively), with much of the region seeing between 0.75” and 1.50” to round of 2018. Temperatures also warmed into the 60s for parts of Indiana and Ohio (Chicago missed out and stayed below 40) to end the year. This capped off the wettest calendar year on record at Columbus, where their 55.18” of rain edging out 2011’s total for most precipitation in a year.
