Springtime Severe Weather Extends Through June

June took up the slack for May’s relatively tame severe weather output—at least by Oklahoma’s standards—with 10 tornadoes and two possible derechos that left over half of a million Oklahomans without power. While storms threatened the state throughout the month, the most intense severe weather was concentrated within just a few days from June 15–18 thanks to two powerful storms systems, both aided by an unusually strong jet stream overhead. The first disturbance kicked off several rounds of storms that impacted the southeastern half of the state and the Panhandle on the 15th. The storms dropped golf ball to grapefruit size hail from the eastern Panhandle to south central Oklahoma. At least four tornadoes were confirmed on the 15th, including a strong EF2 twister that damaged numerous homes on its 4.1-mile path from Stephens County to Jefferson County. Widespread damage was reported indicative of straight-line winds gusting to over 80 mph along a broad path from northwestern through south central Oklahoma. The Oklahoma Mesonet site at Norman recorded a wind gust of 84 mph that evening. Roofs, power lines and poles, and trees suffered considerable damage due to the storms. 

A remarkably similar storm system struck Oklahoma just a couple of days later on the 17th, but this time bringing large hail, tornadoes, and severe straight line winds to the northern half of the state. The Tulsa area bore the brunt of the storms’ fury with reported wind gusts of over 100 mph late on the 17th into the early morning hours on the 18th. The winds devastated the power grid in the area and left nearly 200,000 homes and businesses without power, prompting power utility officials to declare the outages “the most significant restoration event” in the area since a catastrophic 2007 ice storm. At least four tornadoes were spawned by the storms along their paths across northern Oklahoma. The straight-line winds and tornadoes on June 17-18 alone left more than 350,000 Oklahomans without power, some for over a week in stifling heat. A preliminary total of 10 tornadoes was confirmed by National Weather Service personnel, bringing the state’s 2023 total to 62 through the first six months of the year. Oklahoma averages just over 57 tornadoes per year based on data from 1950 through 2022. 

The statewide average rainfall total was 4.58 inches, 0.32 inches above normal and ranked as the 44th  wettest June since records began in 1895. As is usually the case, the rainfall fortunes varied widely across the state. West central Oklahoma and the Panhandle both experienced large average surpluses of 4.09 inches and 2.18 inches, respectively. In an unusual feat for Oklahoma, the west central site at Butler led the state’s totals with 11.85 inches, and its close neighbor Bessie was second with 11.45 inches. Another west central site, Cheyenne, came in a close third with 10.36 inches. Continuing with that theme, 19 of the 20 highest June Mesonet totals came from western Oklahoma—only Centrahoma’s 6.45 inches could make the list from the eastern half of the state. In contrast, east central and northeastern Oklahoma experienced their 33rd and 39th driest Junes on record, respectively. Hollis had the lowest total with 1.72 inches. The first 6 months of the year ended as the 59th wettest on record at 17.99 inches, 0.83 inches below normal. 

The statewide average temperature was 76.2 degrees, 1.1 degrees below normal and ranked as the 44th coolest June since records began in 1895. Temperatures were seasonable through most the month until the final week. A persistent heat dome that had camped across Texas crept north, engulfing Oklahoma and bringing extreme heat with it. Altus hit 113 degrees on the 28th, the highest temperature in the state since July 19, 2022. Heat index values soared into the 110s, topping out at 120 degrees at Grandfield on the 19th and again on the 27th, and Ringling on the 28th. The first 6 month of the year finished at 56.9 degrees, 0.6 degrees above normal and ranked as the 28th warmest January-June on record.