The tumultuous weather of May calmed somewhat with the transition to June, the first month of climatological summer. Despite the seasonal switch, however, there was still plenty of unsettled weather in store for Oklahoma. Western Oklahoma managed to dry out just enough to see the winter wheat harvest make significant advances by the end of the month. Other areas continued to see an active weather pattern with heavy rains, large hail, severe winds, and even tornadoes. At least eight tornadoes touched down during June according to the National Weather Service, bringing the 2019 annual total up to 115. The eight twisters during June is not that unusual – the average for the month is 7.3 – but the annual total ranks as the third highest for the state since accurate records began in 1950. Only 1999’s count of 145 and 2011’s 119 rank higher. Regardless of the total, 2019’s tornadoes have been particularly costly to lives and property. This year’s tornadoes killed four and injured another 41, and produced significant property and infrastructure damage in their wake.
According to preliminary data from the Oklahoma Mesonet, the statewide average rainfall total for the month was 5 inches, 0.48 inches above normal to rank as the 33rd wettest June since records began in 1895. A bit of a drying out occurred across western and parts of north central Oklahoma, but ample moisture along the Interstate 35 corridor and the eastern third of the state more than made up for those deficits. Southeastern Oklahoma was the wettest region of the state at 7.17 inches, a surplus of 2.52 inches and the 15th wettest June for that area. The northeast was not far behind at 7.11 inches, their 21st wettest June with a surplus of 1.88 inches. The southwest experienced a deficit of 1.67 inches on average for their 44th driest June on record. Jay led the state at 12.77 inches, a surplus of 8.6 inches. Fifty-five of the Mesonet’s 120 stations recorded rainfall totals of 5 inches or greater. Bringing up the rear was Eva at 1.12 inches, although four other Mesonet sites – Acme, Freedom, Hollis and Medicine Park – joined Eva by recording less than 2 inches of rain for the month. Combined with the gargantuan totals of May, the June rains propelled the two-month period’s statewide average to 15.52 inches, the fifth wettest on record with a surplus of 6.05 inches. The January-June average of 26.46 inches exceeded normal by 7.43 inches to rank as the seventh wettest such period on record. That six month value is only 10.04 inches less than the normal annual total of 36.5 inches for the state.
Given the enhanced rainfall and associated cloudiness, June was destined to be a cool month. The statewide average temperature of 75.1 degrees was 1.4 degrees below normal to rank as the 28th coolest June since records began in 1895. The first triple-digit reading of the year occurred on the 20th at Altus and Hollis, both reaching exactly 100 degrees. Those extreme temperatures were in short supply during June, however, with only 21 recorded temperatures of 100 degrees or more across the 120 Mesonet sites. Fifteen of those readings occurred on June 21. Hollis led the Mesonet with 104 degrees on the 21st while Eva recorded the lowest temperature of 40 degrees on the 10th. The heat index was bound to spike at times thanks to the excessive rains of May and June. Heat index values rose above 110 degrees across the state on June 20 and 21, with Kingfisher reaching 114 degrees on the 21st. The first six months of the year remained on the cool side with a statewide average of 54.9 degrees, 0.9 degree below normal and the 45th coolest January-June on record.
Drought was of little concern during June. In fact, no drought conditions have been seen in Oklahoma since the March 12 U.S. Drought Monitor, a span of 15 weeks. That duration of drought inactivity in Oklahoma has not occurred since the 38 consecutive drought-free weeks between Sept. 15, 2009, and June 1, 2010. The July temperature and precipitation outlooks from the Climate Prediction Center show increased odds of above normal precipitation and below normal temperatures for most of the state. Accordingly, CPC’s July U.S. Drought Outlook did not foresee any drought development occurring within Oklahoma.