Three soaking storm systems brought much needed precipitation to the state, ending a run of up to 78 days without significant moisture for much of northern and western Oklahoma. Like last year at this time, the winter wheat crop was clamoring for a good drink of water, and fire danger was increasing with each dry, windy day. Between the three storms, virtually all areas of the state saw relief by the end of the month. The most significant storm struck just after Christmas Day and dumped 1-3 inches of rain across a good portion of the state. The western half of the Oklahoma Panhandle saw an old fashioned High Plains blizzard on the back end of the storm. Reports of 4-6 inches of snow were common, with localized amounts of 10 inches near Guymon. Winds of 50 mph closed roads with drifting snow and brought down frozen power lines. A powerful cold front blasted through the state on 2018’s final day, leaving revelers to deal with temperatures in the teens and 20s, and wind chills in the single digits. There was very little severe weather during the month with the storm systems, although flooding was reported with some of the heavier downpours. Preliminary totals from the National Weather Service place the year’s tornado total at 41, about 15 below the 1951-2017 average.
According to the Oklahoma Mesonet, the statewide average precipitation total was 3.54 inches, 1.48 inches above normal to rank as the 14th wettest December since records began in 1895. Southeastern Oklahoma had a surplus of 3.57 inches, the fifth wettest December for that region of the state. Broken Bow led the Mesonet’s 120 stations with 9.12 inches for the month. Thirty-one sites saw at least 5 inches of rain, and another 25 recorded at least 3 inches. Kenton brought up the rear with 0.38 inches. Eight sites reported less than an inch, all in far northwestern Oklahoma. The statewide annual average total of 40.52 inches marks 2018 as the 15th wettest year on record with a surplus of 4.02 inches. South central and southeastern Oklahoma were both 10 inches above normal. Northeastern Oklahoma finished with a deficit of 5.05 inches, the 60thdriest year on record for that region. Broken Bow led the state during 2018 with a total of 73.06 inches, while Kenton had the lowest tally at 15.04 inches. Oklahoma City’s official observation site at Will Rogers Airport recorded 45.85 inches in 2018 to rank as the seventh wettest year since 1890. Tulsa finished on the dry side at 34.08 inches, their 46thdriest year since 1893.
December was on the warm side with a statewide average temperature of 40.3 degrees, 1.4 degrees above normal. That ranked it as the 50th warmest December on record. Several stations logged the month’s highest reading of 69 degrees on various days. Eva recorded the only temperature below zero at minus 2 degrees on the 29th. 2018 was 0.4 degrees above normal at 60.3 degrees, the 41st warmest year on record. The year’s highest temperature of 113 degrees occurred at Grandfield on July 19, as did the highest heat index of 121 degrees at Pawnee. Miami brought in the lowest temperature on Jan. 17 at minus 8 degrees. The lowest wind chill fell on the day before with a teeth-chattering minus 22 degrees.
Drought took a small step forward during December, thanks to the long dry period across northern and western Oklahoma. According to the U.S. Drought Monitor, 5 percent of the state was in at least moderate drought by the end of the month, a minor increase since the end of November. Abnormally dry conditions – a drought precursor – had increased from 27 percent to 45 percent over that same period, however. Much of that dryness was alleviated by the late-month moisture. The January outlooks from the Climate Prediction Center (CPC) showed equal chances for above-, below- and near-normal temperatures and precipitation for Oklahoma. The remaining drought across northeastern Oklahoma was placed in the “removal likely” category on CPC’s January Drought Outlook.