Historic Storm Haunts October

Mon, Nov 02, 2020

A historic winter ice storm struck the state during the last week of October, leaving nearly 400,000 residences and businesses without power. The extreme nature of the event – arguably the most impactful early-season winter storm in the history of Oklahoma – was punctuated by heavy snow in the Panhandle and flooding rains in eastern sections of the state. Trees, still burdened with a full head of leaves so early in the season, were easy prey for radial ice accumulations of up to 3 inches across western and central Oklahoma. Downed branches felled power lines, clogged streets and snarled traffic. The power lines themselves sagged and fell under the weight of the frozen accumulation. Many school districts in the ice storm’s footprint closed for the remainder of the week due to continued challenges with debris and lack of power. Areas to the west received more sleet and snow than freezing rain, and areas to the east were inundated with cold, flooding rains. Snow and sleet totals across far western Oklahoma were generally between 2-4 inches, although as much as 9 inches was reported in localized areas. The frigid weather that came with the storm was as historic as the ice. Record low minimum and maximum temperatures were shattered across western Oklahoma October 26-27. Highs in the Panhandle on the 26^th only rose into the low to mid-20s, breaking their previous record low maximum temperature by 15-20 degrees. The Oklahoma Department of Emergency Management and Homeland Security reported 132 injuries as a result of the storm, with 58 of those from falls and another 28 due to motor vehicle accidents.

The late winter storm provided the first significant moisture since early September for much of western Oklahoma. According to preliminary data from the Oklahoma Mesonet, the statewide average total for the month ended at 3.37 inches, 0.17 inches above normal, to rank as the 45^th wettest October since records began in 1895. Individual amounts from Mesonet sites ranged from 6.9 inches in Cookson to 0.57 inches in Kenton. Despite the deluge, parts of southern Oklahoma were still 2-3 inches below normal for the month. The late burst of moisture helped propel the January-October statewide average to 35.75 inches, 3.82 inches above normal, to rank as the 21^st wettest January-October on record. That surplus was mostly built on gaudy totals 10-20 inches above normal across the southeastern half of the state, however. The western Panhandle and parts of west central Oklahoma had deficits of 7-10 inches over the first 10 months of the year.

The month began on the cool side and finished on the frigid side, resulting in a statewide average temperature of 57.8 degrees, 3.1 degrees below normal, to rank as the 13^th coolest October on record. The state’s first freeze of the season came at Eva and Hooker on the 12^th – just a few days earlier than average – when each bottomed out at 32 degrees. On the other side of the thermometer, 2020’s presumable final triple-digit readings came on the 14^th when Altus, Hollis and Mangum each reached 100 degrees. Grandfield and Hollis each recorded 102 degrees on the 11^th for the month’s highest reading. Boise City and Kenton reported the lowest temperature of the month at 14 degrees on the 26^th. The statewide average year-to-date temperature of 63.4 degrees was 0.4 degrees above normal to rank as the 47^th warmest January-October on record.

Drought surged during October before abating somewhat due to the late-month moisture. Drought coverage reached a high of 38% of the state on October 20 according to the U.S. Drought Monitor, up from 18% at the end of September. The month’s final map on October 27 reflected improvements with drought coverage down to 32% of the state. The outlook for further drought improvement is slim through November for much of the remaining drought area, according to the Climate Prediction Center (CPC). CPC’s November outlooks indicate increased odds of above normal temperature and below normal precipitation for Oklahoma. Their November drought outlook does see some drought improvement across the northwest, but that is for moisture from late October not yet accounted for in the latest Drought Monitor map. The remaining area of drought is expected to persist through November.