2015 Texas–Oklahoma floods

2015 Texas–Oklahoma flood and tornado outbreak

Hydrograph of the Blanco River at Wimberley, Texas depicting the record flood event during the overnight of May 24–25
Type	Extratropical cyclone Tornado outbreak Flood
Formed	May 22, 2015
Dissipated	May 25, 2015
Tornadoes confirmed	75
Max rating1	EF3 tornado
Casualties	58 total deaths: 27 from flooding in Texas 4 from flooding in Oklahoma 14 from a tornado in Ciudad Acuña, Mexico 1 from a tornado near Cameron, Texas 1 from a tornado near Blue, Oklahoma 11 missing from flooding in Texas
Areas affected	Mexico, Great Plains, Southern United States
1Most severe tornado damage; see Fujita scale Part of the Tornadoes of 2015 and Floods in the United States during 2015

58 total deaths:

¹Most severe tornado damage; see Fujita scale

Preceded by more than a week of heavy rain, a slow-moving storm system dropped tremendous precipitation across much of Texas and Oklahoma during the nights of May 24–26, 2015, triggering record-breaking floods. Additionally, many areas reported tornado activity and lightning. Particularly hard hit were areas along the Blanco River in Hays County, Texas, where entire blocks of homes were leveled. On the morning of May 26, the National Weather Service issued a flash flood emergency for southwest Harris County (which includes the city of Houston) and northeast Fort Bend County. The system also produced deadly tornadoes in parts of Mexico, Texas, and Oklahoma.

According to Bob Henson from Wunderground, inflow of low-level moisture from the Gulf of Mexico and the combination of very slow moving large-scale storm systems set the stage for the floods. He added,"Upper-level winds were largely aligned with the low-level frontal zone, an ideal setup for “thunderstorm training” (successive downpours over the same area). In addition, rains were concentrated by several mesoscale convective vortices, small-scale centers of low-pressure that developed along the frontal bands, in some cases resembling mini-tropical cyclones." The stationary trough during May is linked to both the El Niño and amplified midlatitude short-wave train.

On May 14, 2015, prior to extensive flooding beginning around May 24, flash flood warnings were issued for counties in South East Texas. At least 31 people were killed, including 27 in Texas and 4 in Oklahoma, and another 11 remain missing.

Flooding along the Wichita River prompted evacuations of 390 homes in Wichita Falls. Projections from the National Weather Service indicated that the river would reach a record crest of 25.5 ft (7.8 m) on May 26. Up to 100,000 customers were without power.