August Rains Tackle Drought

Drought had gained a toehold across western and central Oklahoma during a hot, dry first half of August; further spread and intensification seemed inevitable. All the while eastern Oklahoma was being inundated by heavy rains and flooding. Then the rains spread west, bringing a hefty dose of severe weather and drought relief with them. Mother Nature put an exclamation point on the tumultuous weather on August 26. A stifling day with temperatures in the 100s saw the heat index soar as high as 118 degrees before severe storms – including an EF-1 tornado – blasted the state later that evening. Nearly 100,000 residents were left without power as straight-line winds of up to 90 mph struck central and northeastern Oklahoma. The tornado traveled from Logan County to just north-northwest of Edmond, damaging trees and a few structures along its path. Another weak tornado dropped in Beaver County on the 23rd, again damaging trees and a few structures. The two confirmed twisters brought Oklahoma’s 2019 total to at least 138, the second highest count since accurate records began in 1950. The highest total of 145 tornadoes occurred in 1999.

The statewide average rainfall total was 5.44 inches according to preliminary data from the Oklahoma Mesonet, 2.49 inches above normal and ranked as the eighth wettest August since records began in 1895. Nearly the entire state had a surplus of moisture, save for southwestern and west central Oklahoma where deficits of up to 2 inches occurred. Surpluses ran from 2-4 inches across northwestern Oklahoma to more than 10 inches across the northeastern quarter of the state. Northeastern Oklahoma experienced its wettest August on record with an average of 8.78 inches, 5.54 inches above normal. Twelve of the Mesonet’s 120 sites recorded at least 10 inches of rain, and another 51 had 5 inches or more. The Mesonet site at Oilton led the state with 13.64 inches. Valliant brought up the rear with 0.81 inches, the only site that failed to receive at least an inch of rain for the month. The climatological summer (June-August) ended as the 30th wettest on record at 12.14 inches, 1.79 inches above normal. The northeast also experienced its wettest January-August on record at 47.46 inches, 18.57 inches above normal. The statewide average was 33.87 inches, 9.01 inches above normal to rank as the fifth wettest January-August on record.

The statewide average temperature was 81.8 degrees, a degree above normal to rank as the 46th warmest August on record. Drought-stricken western Oklahoma was 3-4 degrees above normal, while the rainy northeast was 2-4 degrees below normal. Several Mesonet sites reached 108 degrees for the highest temperature of the month. Kenton recorded the lowest reading of 55 degrees on three separate days. The actual air temperature failed to adequately describe the oppressive nature of August’s heat, however. Combined with an abundance of humidity, the heat index soared. The Mesonet’s 120 sites reached a heat index of at least 115 degrees 45 times during August, and at least 110 degrees 566 times. At least one site reached a heat index of 105 degrees on 23 separate days. The summer was a bit mild at 0.3 degrees below normal. The first eight months were on the cool side – about 0.7 degrees below normal, the 48th coolest January-August on record.

Oklahoma’s drought coverage grew from 6 percent at the end of July to nearly 24 percent by August 20, according to the U.S. Drought Monitor. While the total coverage decreased to about 18 percent by month’s end, the drought’s intensity increased in the parched southwestern corner of the state. The Climate Prediction Center’s (CPC) September outlooks called for increased odds of above normal precipitation across the northwestern half of the state, but equal chances for above-, below-, or near-normal rainfall in the remainder of Oklahoma. Equal odds were also indicated across the entire state for temperature. CPC’s September drought outlook shows drought persisting in south central Oklahoma, but some improvement is expected farther to the west. No additional development is expected.