Drought and Heat Roar Back in August

Oklahoma tried its best Al Pacino impression from “The Godfather Part III” during August, being pulled back into drought after nearly escaping its clutches completely thanks to record moisture the previous three months. The heat and dry weather roared back with a vengeance, however, and flash drought erupted for the second consecutive summer. Only 13% of the state was in drought on Aug. 8 according to the U.S. Drought Monitor, contained entirely in small patches across far southwestern and north central Oklahoma. That amount had increased to 36% in just three weeks’ time, and the percentage of the state in at least severe drought rose from 6% to 20% over that period. The entirety of that increase occurred in the southern half of the state where some Oklahoma Mesonet sites had gone as many as 53 days without a quarter-inch of rain in a single day. The flash drought left much of southern Oklahoma with flagging soil moisture, dead and dormant vegetation, and critical wildfire conditions.

Dangerous heat plagued Oklahoma thanks to the abundant rains from the previous three months and a persistent high pressure dome that camped over the state. The Mesonet’s all-time record high heat index fell twice on Aug. 21 as Miami reached an oppressive 126 degrees, only to see that mark fall a couple of hours later when Jay reached 127 degrees. Mesonet temperature records date back to 1997. The Mesonet’s 120 sites reached a heat index of at least 120 degrees 41 times during the month, and at least 115 degrees an additional 171 times. The Mesonet’s record high dew point temperature was eclipsed three times during the month, the final winner being Jay’s 85.14 degrees on Aug. 21.

The statewide average precipitation total for the month finished at 2.23 inches according to the Oklahoma Mesonet, 1 inch below normal and ranked as the 44th driest August since records began in 1895. The month’s rainfall was yet another tale of the haves versus have-nots in Oklahoma, with the southwestern half of the state going largely without rainfall through the month, while the northeastern half enjoyed more robust totals. Widespread deficits of 1-3 inches were common across the southwestern half, with similar surpluses to the northeast. Totals ranged from 6.86 inches at Jay to 0.02 inches at both Grandfield and Ringling. Thirty-seven of the Mesonet’s 120 sites recorded an inch or less for the month. The June-August statewide average finished at 12.31 inches, 1.62 inches above normal and ranked as the 29th wettest climatological summer on record. West central Oklahoma’s average of 15.82 inches ranked as their wettest summer on record, 6.35 inches above normal. The first eight months of the year were the 43rd wettest with a statewide average of 25.67 inches, 0.42 inches above normal.

The statewide average temperature for the month was 83.1 degrees, 2.3 degrees above normal and ranked as the 28th warmest August on record. Southwestern and southeastern Oklahoma experienced their 8th warmest Augusts on record, and south central finished with their 14th warmest. Grandfield was the hottest site with an August average high temperature of 105.4 degrees, and reached triple-digit temperatures on 25 of August’s 31 days. The month’s highest reading of 114 degrees was reported at Grandfield on the 18th, and the lowest reading of 51 degrees occurred on the 30th at Eva. Despite the unusually mild weather of June and most of July, summer still finished 0.6 degrees above normal at 80.6 degrees, the 38th warmest June-August since records began in 1895. The first eight months of the year were similarly warm at 63.5 degrees, 0.8 degrees above normal and ranked as the 24th warmest January-August on record.

The prospects for drought relief look somewhat bleak according to the Climate Prediction Center’s September outlooks, which indicate increased odds for above normal temperatures and below normal precipitation for the entire state. Those odds are particularly enhanced for both across the western three-fourths of the state, each of which could lead to further drought intensification should they occur. CPC’s September drought outlook reflects that possibility with drought persistence or development considered “likely” across the entire state.