Drought Returns During July

Thu, Aug 01, 2019

Drought returned to the state for the first time since March 12, a stark reminder that spring deluges can quickly be forgotten during the unforgiving Oklahoma summer. The abrupt end of the moisture actually extended back to mid-June in some areas, but the deficits widened further during July. The lack of rain coincided with intermittent periods of hot, windy weather. Those sporadic bouts of extreme summer conditions helped to accelerate the drought development process, despite the month being cooler than normal overall. Severe weather still made its presence known with reports of the customary culprits, including high winds, large hail, and flash flooding. There were no official reports of tornadoes. The preliminary Oklahoma twister count for 2019 stood at 129 at the end of July, the second highest total since accurate records began in 1950. The highest total of 145 occurred in 1999.

According to preliminary data from the Oklahoma Mesonet, the statewide average rainfall total was 1.63 inches, 1.25 inches below normal, to rank as the 29^th driest July since records began in 1895. Rainfall fortunes varied widely across the state. Substantial rains fell across much of eastern Oklahoma, where totals of 3-5 inches were common. Copan led the Mesonet at 5.81 inches, with Wister a close second at 5.35 inches. Significant deficits reigned across much of central and western Oklahoma. Forty-five of the Mesonet’s 120 stations recorded less than an inch of rain for the month, while 87 received less than 2 inches. Chickasha had the lowest total at 0.03 inches, although Minco was close behind with 0.04 inches. The Oklahoma City official observing site at Will Rogers Airport recorded 0.06 inches, tied for its fourth driest July on record. By the end of July, parts of north central Oklahoma had gone 45 days without at least a quarter-inch of rainfall. That streak extended to 38 days across central and southwestern Oklahoma. Chickasha, Hobart and Minco had gone 38 consecutive days without at least a tenth of an inch. The first seven months of the year were still extremely wet with a January-July statewide average of 27.86 inches, a surplus of 5.95 inches and the ninth wettest such period on record.

The statewide average temperature was 80.2 degrees, 1.3 degrees below normal to rank as the 34^th coolest July on record. Several cold fronts helped keep the extreme heat confined within shorter windows. The strongest of those fronts moved through the state on the 22^nd, dropping high temperatures into the low 80s. Lows in the 50s were common, and Camargo dropped to 48 degrees on the 24^th for the month’s lowest reading. More than a dozen low temperature records were set across the state that morning. Extreme heat still visited at times, however. Kenton recorded July’s highest temperature at 107 degrees on the 19^th. The Mesonet measured heat index values of at least 110 degrees 154 times during the month, maxing out at 116 degrees at Burneyville on July 10. The year continues to run on the cool side. The January-July statewide average was 58.6 degrees, a degree below normal, to rank as the 42^nd coolest such period on record.

Nearly 6% of the state was in moderate drought according to the July 30 U.S. Drought Monitor report, and another 13% was considered “abnormally dry,” a drought precursor. Those designations cover most of the southwestern quarter of the state, with another dollop centered over Ellis County in the northwest. Drought development is considered likely across the western two-thirds of the state through the end of August according to the Climate Prediction Center’s (CPC) monthly drought outlook. That drought development would be in addition to those areas that saw drought advance by the end of July. CPC’s temperature and precipitation outlooks for August indicate increased odds of above normal temperatures across the southwestern one-third of the state, and above normal precipitation over far northeastern Oklahoma.