Flash Flood — Hays, Texas

2015-10-30 · near Driftwood, Hays, Texas

Event narrative

Massive flooding occurred along and just west of Interstate 35 on the morning of October 30th as a supercell thunderstorm merged with another line of storms. Torrential rains with rain rates of 7+ inches per hour caused massive runoff and quickly flooded the Blanco River, Onion Creek, Plum Creek, the San Marcos River and other smaller creeks and streams. Rainfall totals along I-35 were as high as 16 inches which led to significant flooding in Kyle and Buda as well. Sections of I-35 were shut down as water made the interstate impassable. Areas of San Marcos were inundated with water, trapping people and school kids. Dozens of swift water rescues continued during the morning and afternoon. The extent of the flooding was similar to the historic flood of October 1998. Hundreds of homes were flooded, as many as 100 of them completely destroyed. These estimates are probably low as FEMA assessments are still ongoing as of this writing. Infrastructure losses to roads and bridges are in the millions. There are no monetary loss estimates to uninsured/insured homes at the time of this writing.

Wider weather episode

A warm front combined with an upper level trough and deep moisture produced heavy rainfall and severe thunderstorms across much of South Central Texas on October 30th and 31st. Damage surveys confirmed four tornadoes. Along with the severe weather, excessive rainfall resulted in widespread flash flooding along the Interstate 35 corridor Friday morning. Rainfall rates on the order of 5-7 inches per hour fell from San Marcos up through South Austin. Historic rainfall totals fell at the Austin Airport where over 1 foot of rain fell within a few hours time. 12.49 inches of rain for Oct 30 was the most ever in one day for Austin. Other daily rainfall totals exceeded 15 inches. Record flooding occurred in southern Travis County and portions of Hays County. River and creek flooding was extensive across Hays, Travis, Bastrop, Caldwell, and Comal Counties. Many areas, especially in San Marcos, compared this flooding to the record flooding of Oct 1998. Estimates of 2000 homes were flooded in or near this I-35 corridor, many of them destroyed or sustained Major damage. Estimates of insured losses were not available as of this writing, but the counties experienced monetary losses in the tens of millions.

View location on OpenStreetMap → (30.1340, -98.0241)

Source: NOAA Storm Events Database, event_id 606070. Narrative written by the NWS forecast office that issued the report.