May Rains Dent Drought

Wed, Jun 01, 2022

May’s reputation as Oklahoma’s most prolific severe weather month was confirmed within the first week with as many as 21 tornadoes in the month’s first five days. While most of that count were weak EF0 or EF1 tornadoes, they were damaging, nonetheless. That total also included two strong EF2 twisters that struck both Earlsboro and Seminole on May 4. The Earlsboro tornado traveled in nearly a complete circle, producing damage in the southeast side of the city first and then the northeast side along its circuitous route. The Seminole twister grew up to a mile wide with multiple vortices at times and was on the ground for 12 miles. Unfortunately, part of that path took it through downtown Seminole where it produced significant damage to homes, businesses, and two Seminole schools. That same tornadic storm also produced a large damaging EF1 tornado near Cromwell and Okemah. Another large tornado reached nearly a mile wide and produced EF1 damage in Le Flore County earlier on May 2. Nearly 10,000 electric customers were left without power following the multi-day severe weather event, and there were at least 21 storm-related injuries. Reports of large hail were common throughout the month. Hail to the size of grapefruits was reported near Seminole on May 2 and again at Okemah on May 15. Prodigious rains not only took a huge bite out of the drought, but also produced widespread flooding—especially across eastern Oklahoma where more than a foot of precipitation fell. The month ended much as it began with severe storms rolling across the state producing large hail, severe winds, and flooding rainfall on May 31.

The statewide average rain total was 6.33 inches according to preliminary data from the Oklahoma Mesonet, 1.4 inches above normal and ranked as the 30^th wettest May since records began in 1895. For the first time since June 2021, all 120 Oklahoma Mesonet sites received at least an inch of rainfall. Those totals ranged from 1.04 inches at Eva to 13.9 inches at Haskell. Nineteen Mesonet sites recorded at least 10 inches of rain for the month, and another 65 reached the 5-inch mark. For some parts of western Oklahoma, it was more moisture than they had in the previous eight months totaled together, dating back to September 2021. The climatological spring (March-May) finished with a statewide average of 11.51 inches, 0.21 inches above normal and ranked as the 43^rd wettest March-May on record. The first five months of the year had a statewide average of 13.85 inches, 0.71 inches below normal and ranked as the 56^th wettest January-May on record.

The statewide average temperature finished at 70.3 degrees, 1.9 degrees above normal to rank as the 29^th warmest May on record. Temperatures soared into summer-like territory for much of the middle of the month, with significantly cooler weather bookending that burst of summer. The Mesonet’s 120 sites recorded triple-digit temperatures 82 times on 12 separate days during May. Altus had 11 days at or above 100 degrees during the month to lead the state, although Hollis was close behind at 10 days. Temperatures ranged from a high of 108 degrees at Grandfield on May 8 to a low of 32 degrees at Eva on the 22^nd—undoubtedly Oklahoma’s last freeze of the spring season. Spring ended as the 31^st warmest on record at 60.6 degrees, 0.9 degrees above normal. The first five months of the year remained 0.4 degrees below normal with a statewide average of 51.7 degrees, the 47^th warmest January-May on record.

Drought took a major hit during May. According to the U.S. Drought Monitor, coverage dropped from 65% at the end of April to 44% at the end of May. The two most intense categories of drought—extreme and exceptional—fell by more than half from 39% to 18%. The June outlooks from the Climate Prediction Center hold some promise for more drought relief. The rainfall outlook shows increased odds of above normal moisture across the northeastern half of the state, while temperatures are expected to be above normal across much of southern and western Oklahoma. With heavy rains forecast for the first week of June, the June drought outlook indicates improvements are likely across all of the state save for the Panhandle and extreme southern Oklahoma where persistence is favored.