Flash Flood — Travis, Texas

2013-10-31 · near Oak Hill, Travis, Texas

Event narrative

Heavy rains in excess of 14 inches upstream of Austin in the Onion Creek Watershed near Wimberley caused a flash flood that hit portions of South Austin in the early morning hours. Water started to rise and flood portions of the Onion Creek area near Interstate 35 by 4-5am on the morning of the 31st and water continued to rise into the early morning hours. USGS gauges were overtopped near Twin Creek Road and this record flood water continued to move along Onion creek, passing under I-35 and inundating several neighborhoods between I-35 and US Highway 183. A reverse 911 was utilized by the City of Austin to help evacuate residents but flood waters rose so quickly that most residents sheltered in place and were rescued by truck and helicopter later that morning. Those that tried to escape the flood waters via their vehicles got caught in the rising waters and this led to several fatalities. A mother and infant son died when their SUV vehicle was swept off the Onion Creek bridge on Bluff Springs Road in the predawn hours around 430 am. Another resident in a neighborhood along Onion Creek was also found drowned as his vehicle got swept off the road and was recovered near Pleasant Valley Drive and William Cannon. Almost 2 weeks later the body of a homeless man was found in Williamson Creek near South First Street and Heartwood. He was presumed a flood fatality from this event. Manual readings were performed by USGS at the Onion Creek/Highway 183 gauge site ATIT2. The creek crested just over 40 feet at 930 am the morning of October 31st. This was a new record height for this location and translated to about 135,000 cubic feet per second. In total across Travis County and the City of Austin, over 700 homes were damaged by the flooding, of which over 100 were destroyed. Most of the affected homes did not have insurance and were within the 100 year flood plain of Onion Creek. Flood recovery lasted for several weeks including debris removal. Damage estimates are still being calculated as of this writing but damages across Travis County and the City of Austin look like they will exceed 100 million dollars.

Wider weather episode

Prolonged flow from the Gulf of Mexico produced a deep moist layer at the surface with precipitable water values two standard deviations above the mean on area soundings. An upper level trough of low pressure moved out of northern New Mexico and across the Texas Panhandle providing lift to produce showers and thunderstorms. A surface trough was the focus of training storms which produced heavy rainfall that led to major flooding across the Onion Creek and Blanco/San Marcos River watersheds.

View location on OpenStreetMap → (30.2033, -97.8463)

Source: NOAA Storm Events Database, event_id 481489. Narrative written by the NWS forecast office that issued the report.