Overachieving Severe Season Continues During May

Oklahoma continued to suffer from severe weather in May, marking an exceptionally active spring storm season. The state recorded four more storm-related fatalities in May, bringing the total to eight in 2024, along with hundreds of injuries. At least 43 tornadoes touched down in May, following a record-breaking 55 tornadoes in April, surpassing the previous high of 54 in 2012. With two additional tornadoes in March, the preliminary total for 2024 stands at 100, a number that may rise as National Weather Service personnel continue to assess storm damage. The supercell thunderstorms that generated these tornadoes also brought numerous reports of hail, severe winds, and flash flooding. At times, the hail was larger than softballs, and damaging winds reached speeds of nearly 100 mph. Overall, there was at least one severe storm report collected by Oklahoma’s local NWS offices on 22 out of 31 days in May.

Two fatalities and 33 injuries occurred on May 6 with a long-track, violent EF4 tornado that started near Hominy and plowed into Barnsdall in Osage County, with estimated wind speeds of up to 175 mph. The tornado caused considerable damage before moving northeast into Bartlesville, where it eventually dissipated. This was the second EF4 tornado in Oklahoma in 2024, following the April 27 Marietta tornado. This marks the first instance of multiple violent EF4 or EF5 tornadoes in the state since 2013. The other two fatalities were associated with a long-track EF3 tornado that developed northeast of Owasso in Rogers County on May 25. It moved through Claremore, destroying numerous homes and businesses, before tracking east into Mayes County. The tornado killed two and injured four more in a mobile home near Pryor. At times, the tornado reached over a mile wide, with estimated wind speeds of up to 155 mph.

According to preliminary data from the Oklahoma Mesonet, the statewide average rainfall total for May was 5.43 inches, 0.5 inches above normal, ranking as the 45th wettest May since records began in 1895. Due to the convective nature of May’s precipitation, the rainfall pattern was a hodgepodge of deficits of about an inch or less and surpluses of 2-4 inches. Idabel led all Mesonet sites with a total of 11.65 inches, featuring a 6.1-inch surplus. Fifty of the Mesonet’s 120 sites recorded at least 6 inches of rainfall during May, and another 27 recorded at least 5 inches. Eva had the lowest total at 1.29 inches, joining four other sites with less than 2 inches. Climatological spring, which runs from March 1 through May 31, ended as the 47th wettest in Oklahoma with a statewide average of 11.29 inches, matching the seasonal normal. Deficits of 2-5 inches were noted across the northwestern quarter of the state and from central through northeastern Oklahoma. Meanwhile, widespread surpluses of 2-4 inches spread across much of southern and eastern Oklahoma. As in May, Idabel led all sites with a spring total of 24.1 inches—8.6 inches above normal—while Eva recorded the lowest at 1.7 inches. The first five months of the year finished with 14.93 inches, 0.38 inches above normal, ranking as the 45th wettest January-May on record.

May was a warm month in Oklahoma. No locations reached the freezing mark during the month, with the spring’s final freeze confirmed on April 22. The statewide average temperature for May, as determined by Mesonet data, was 70.2 degrees, 1.8 degrees above normal, ranking as the 30th warmest May since records began in 1895. Three sites reached triple digits on May 20, including Altus at 101 degrees, the highest temperature of the month. Hollis and Erick also reached 100 degrees that day. There were 39 readings of heat index values of 100 degrees or greater, with the combination of heat and atmospheric moisture fueling the month’s severe weather. Altus and Burneyville both reached 106 degrees on May 25 and 24, respectively. The lowest temperature was 36 degrees at Eva on May 8. Climatological spring finished as the fifth-warmest on record at 62.5 degrees, 2.8 degrees above normal. The first five months of the year also ranked as the fifth-warmest January-May at 54.3 degrees, 2.2 degrees above normal.

Drought diminished considerably through May, decreasing from around 28% of the state at the end of April to less than 15% at the end of May. While drought had disappeared throughout most of Oklahoma, it continued to spread west through the Panhandle and south into far western areas of the state. The Climate Prediction Center’s June drought outlook calls for most of the drought in the state to improve through the month, except in the western half of the Panhandle. The CPC’s June precipitation and temperature outlooks indicate increased odds of both for the month.