Preceded by more than a week of heavy rain, a slow-moving storm system dropped tremendous precipitation across much of

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

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 Hays County is located on the Edwards Plateau in the U.S. state of Texas. Hays County is part of the Austin-Round Rock metropolitan area. As of the 2020 census, its official population had reached 241,067. The county seat is San Marcos. Ha ...

, where entire blocks of homes were leveled. On the morning of May 26, the

National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...

issued a

flash flood emergency A flash flood warning ( SAME code: FFW) is an hazardous weather statement issued by national weather forecasting agencies throughout the world to alert the public that a flash flood is imminent or occurring in the warned area. A flash flood is a ...

for southwest Harris County (which includes the city of

Houston Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 i ...

) and northeast

Fort Bend County Fort Bend County is a county located in the U.S. state of Texas. The county was founded in 1837 and organized the next year. It is named for a blockhouse at a bend of the Brazos River. The community developed around the fort in early days. Th ...

. The system also produced deadly tornadoes in parts of

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, Texas, and Oklahoma. This flood significantly contributed to the wettest month ever for

and Oklahoma.

Meteorological synopsis

According to Bob Henson from Wunderground, inflow of low-level moisture from the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

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 In meteorology, training denotes repeated areas of rain, typically associated with thunderstorms, that move over the same region in a relatively short period of time. Training thunderstorms are capable of producing excessive rainfall totals, ofte ...

” (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 El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...

and amplified midlatitude short-wave train.

Flooding

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 14 people were killed, including 10 in Texas and 4 in Oklahoma, and another 11 remain missing.

Texas

Flooding along the

Wichita River The Wichita River ( ), part of the Red River watershed, lies in north-central Texas. Rising in northeastern Knox County at the confluence of its North and South Forks, the river flows northeast across Baylor, Archer, Wichita, and Clay count ...

prompted evacuations of 390 homes in

Wichita Falls Wichita Falls ( ) is a city in and the seat of government of Wichita County, Texas, United States. It is the principal city of the Wichita Falls Metropolitan Statistical Area, which encompasses all of Archer, Clay, and Wichita counties. According ...

. Projections from the

indicated that the river would reach a record crest of on May 26. Up to 100,000 customers were without power.

and Corpus Christi broke their previous records for all-time wettest month. Many parts in northern Texas recorded over of rain. A 25-foot-by-25-foot

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

near a runway at the

Dallas/Fort Worth International Airport Dallas/Fort Worth International Airport , also known as DFW Airport, is the primary international airport serving the Dallas–Fort Worth metroplex and the North Texas Region in the U.S. state of Texas. It is the largest hub for American Ai ...

caused the closure of the runway for a few hours. Also on May 25, historic flooding along Shoal Creek inundated House Park in

Austin, Texas Austin is the capital city of the U.S. state of Texas, as well as the seat and largest city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the 11th-most-populous city ...

damaging the turf among other things and forcing the Austin Aztex to search for a temporary home.

Houston

More than 500 water rescues were carried out by firefighters, which involved for the most part stranded motorists. At least 2,500 vehicles were abandoned, when drivers had to seek higher grounds. During the overnight of May 25–26, nearly of rain fell near

, setting off further flash floods. Two people drowned after being trapped in their cars while a third was later found in bayou. A fourth person lost their life when an evacuation boat capsized during the morning of May 26. On May 26, Houston Mayor Annise Parker, estimated up to 4,000 properties with ''significant damage''.

Blanco River

During the overnight of May 24–25, more than fell along the watershed of the Blanco River. In just a few short hours, the river rose from roughly to a crest just over , well over the flood-stage, near Wimberley. This broke the river's all-time peak of set in 1929. Tremendous flash flooding ensued as a result, with areas of

Hays County Hays County is located on the Edwards Plateau in the U.S. state of Texas. Hays County is part of the Austin- Round Rock metropolitan area. As of the 2020 census, its official population had reached 241,067. The county seat is San Marcos. H ...

being particularly hard hit. Entire blocks of homes in Wimberley were swept away by a "tidal wave of water" with officials reporting 350–400 residences destroyed in the town alone. For the first time, the river covered portions of

Interstate 35 Interstate 35 (I-35) is a major Interstate Highway in the central United States. As with most primary Interstates that end in a five, it is a major cross-country, north–south route. It stretches from Laredo, Texas, near the Mexican border ...

, shutting down traffic for hours. Large trees and debris were deposited across the roadway. One person in San Marcos, Texas was confirmed dead. Thirteen people were carried away when the home they were in was swept downstream. Residents reported seeing it being destroyed after striking a bridge. One occupant was recovered with significant injuries while the other twelve remain missing. At least 1,200 people have been left homeless along the river.

Oklahoma

On May 23, flash flooding along Highway 20 near

Claremore Claremore is a city and the county seat of Rogers County in Green Country or northeastern Oklahoma, United States. The population was 19,580 at the 2020 census, a 5.4 percent increase over the figure of 18,581 recorded in 2010.OG&E customers experienced power outages as a result of the flooding in Oklahoma City and Del City. A station

Oklahoma City Oklahoma City (), officially the City of Oklahoma City, and often shortened to OKC, is the capital and largest city of the U.S. state of Oklahoma. The county seat of Oklahoma County, it ranks 20th among United States cities in population, a ...

recorded of rainfall in May 2015, which made it the all-time wettest month on record. Records date back to 1890. From May 1 to May 25, 122 tornado warnings were reported by the National Weather Service in Oklahoma, more than in the same period The Oklahoma Department of Transportation reported on May 26 that a number of highways were closed because of high water or damage from previous flooding.

Louisiana

Flooding in Ruston, Louisiana on 18 May caused an eleven-year-old boy to drown in a submerged car along Colvin Creek.

Response

Texas Governor declares state of disaster in 37 counties

On May 24, voluntary evacuations were extended to include 2,177 homes near the

. On May 25, near

, about 400 homes were placed under mandatory evacuation orders downstream from the Louis Creek Dam. On May 25,

Texas Governor The governor of Texas heads the state government of Texas. The governor is the leader of the executive and legislative branch of the state government and is the commander in chief of the Texas Military. The current governor is Greg Abbott, who ...

Greg Abbott Gregory Wayne Abbott (born November 13, 1957) is an American politician, attorney, and former jurist serving as the 48th governor of Texas since 2015. A member of the Republican Party, he served as the 50th attorney general of Texas from 2002 ...

declared a state of emergency for 24 counties as a result of the ongoing disaster, and called the floods the biggest in Texas history. On May 26, President

Barack Obama Barack Hussein Obama II ( ; born August 4, 1961) is an American politician who served as the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, Obama was the first African-American president of the ...

announced federal resources to help affected areas in Texas, and signed a disaster declaration for Oklahoma. Houston Mayor Annise Parker declared a local state of disaster for the city of Houston on May 26. On May 26, Governor

Mary Fallin Mary Fallin (; née Copeland; born December 9, 1954) is an American politician who served as the 27th governor of Oklahoma from 2011 to 2019. A member of the Republican Party, she was elected in 2010 and reelected in 2014. She was the first and s ...

declared a state of emergency for all 77 counties in Oklahoma.

Climate change

A study by Utah State University analyzed the pathway in which anthropogenic global warming contributed to the persistent precipitation in May 2015: Warming in the tropical Pacific acted to strengthen the teleconnection toward North America, modification o
zonal wave-5 circulation
that deepened the stationary trough west of Texas, an
enhanced Great Plains low-level southerlies
increasing moisture supply from the Gulf of Mexico. Attribution analysis indicated a significant increase in the El Niño-induced precipitation anomalies over Texas and Oklahoma when increases in the anthropogenic greenhouse gases were taken into account. Studies by the Scripps Institution of Oceanography found for Texas that precipitation totals have increased 10 percent in the last century, but mostly in eastern Texas, with more frequent, severe and longer drought conditions in west Texas. The report ''Regional Climate Trends and Scenarios for the U.S. National Climate Assessment'' ( NCA) from 2013 by NOAA, projects that parts of Texas, and parts of the Great Plains region can expect up to 30% (High emissions scenario based on CMIP3 and NARCCAP models) increase in extreme precipitation days by midcentury. This definition is based on days receiving more than one inch of rainfall. A study from April 2015 concluded that about 18% of the moderate daily precipitation extremes over land are attributable to observed temperature increase since the

Industrial Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

and that this primarily results from human influence.

Tornado events

*Note: One tornado in Mexico was rated F3 but is listed as EF3 in the above table for convenience.

May 23 event

May 24 event

May 25 event

Notes

References

{{DEFAULTSORT:2015 Texas-Oklahoma floods Texas-Oklahoma floods, 2015 Floods Floods Floods Floods Floods 2015 meteorology F3 tornadoes Floods in Texas

May 23 Events Pre-1600 * 1430 – Joan of Arc is captured at the Siege of Compiègne by troops from the Burgundian faction. *1498 – Girolamo Savonarola is burned at the stake in Florence, Italy. * 1533 – The marriage of King Henry VI ...

2015 natural disasters in the United States 2015 in Mexico Natural disasters in Mexico May 2015 events in the United States 2015 disasters in Mexico 2015 floods in the United States