Why this state is home to ‘Flash Flood Alley'
By
Zachary Rosenthal, AccuWeather staff writer
Published Apr 8, 2022 11:58 AM EDT
|
Updated Apr 8, 2022 1:51 PM EDT
Experts say weather patterns, rising terrain and drainage challenges are a few of the factors that make one part of Texas the most prone to flash flooding.
Everything is bigger in Texas, and that includes the flash flood risk in one particular stretch of the Lone Star State.
Many of the state's big cities are familiar with the risk of flooding. Houston has seen regular flooding from heavy thunderstorms as well as major hurricanes such as Hurricane Harvey, which flooded Houston as a tropical storm. Waco had a major flood back in the 1930s, which the city's website says caused more than $1 million in damage. In Austin, floodwaters burst into the state capitol building in late April 2021 as up to 5 inches of rain fell in the city, according to The Texas Tribune.
These fairly regular flash floods have led officials to nickname a part of the state 'Flash Flood Alley,' a geographic region that tracks through many of Texas' major metropolitan areas, including San Antonio, Dallas, Austin and Waco.
The Balcones Escarpment, which roughly parallels Interstate 35, marks the location of flash flood alley. The inactive fault zone formed a rise in the topography in the area, which enhances storm systems that pass over it, causing them to dump more rain there than they might elsewhere.
"We're going from the coastal plains right into the hill country. There's a rise of at least about 500 feet in elevation," Pete Rose, a meteorologist with the Lower Colorado River Authority, told AccuWeather National Reporter Bill Wadell.
"Along with that, you have a lot of your hills and valleys that go along with that type of topography, and these hills don't contain a lot of soil; they have very thin soil. So when rain does hit them, not much of it gets absorbed," Rose said, noting that water will rush down the valleys and pile into creeks and streams.
Warm, moist air from the Gulf of Mexico helps fuel storms as well, giving them ample moisture to dump lots of rain in a short amount of time across the dusty Texas soil.
Joggers run near the White Rock Lake spillway during a rain shower Monday, June 7, 2021, in Dallas. Passing rain storms caused flash flooding warnings in North Texas due to an already water-saturated area that has seen record rainfalls. (AP Photo/LM Otero)
Flood experts believe that the future will bring an increased risk of flash flooding to this already flood-prone area, as more development in the region creates more impermeable surfaces and thus more runoff. Bigger storms, enhanced by a changing climate, may also lead to more flash flooding as a warmer atmosphere allows storms to hold more water.
Cities such as Austin have been taking preventative measures to warn locals about the threat of flash flooding, putting up signs in areas that flood frequently. Austin also has the Flood Early Warning System, a network of rain gauges, barricades and cameras that monitor the threat of flooding in the city.
"We're in a very, very flash flood-prone area, not only of Texas but out of the country and even the world," Rose said.
Reporting by AccuWeather's Bill Wadell
For the latest weather news check back on AccuWeather.com. Watch the AccuWeather Network on DIRECTV, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeather Now is now available on your preferred streaming platform.
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News / Weather News
Why this state is home to ‘Flash Flood Alley'
By Zachary Rosenthal, AccuWeather staff writer
Published Apr 8, 2022 11:58 AM EDT | Updated Apr 8, 2022 1:51 PM EDT
Experts say weather patterns, rising terrain and drainage challenges are a few of the factors that make one part of Texas the most prone to flash flooding.
Everything is bigger in Texas, and that includes the flash flood risk in one particular stretch of the Lone Star State.
Many of the state's big cities are familiar with the risk of flooding. Houston has seen regular flooding from heavy thunderstorms as well as major hurricanes such as Hurricane Harvey, which flooded Houston as a tropical storm. Waco had a major flood back in the 1930s, which the city's website says caused more than $1 million in damage. In Austin, floodwaters burst into the state capitol building in late April 2021 as up to 5 inches of rain fell in the city, according to The Texas Tribune.
These fairly regular flash floods have led officials to nickname a part of the state 'Flash Flood Alley,' a geographic region that tracks through many of Texas' major metropolitan areas, including San Antonio, Dallas, Austin and Waco.
The Balcones Escarpment, which roughly parallels Interstate 35, marks the location of flash flood alley. The inactive fault zone formed a rise in the topography in the area, which enhances storm systems that pass over it, causing them to dump more rain there than they might elsewhere.
"We're going from the coastal plains right into the hill country. There's a rise of at least about 500 feet in elevation," Pete Rose, a meteorologist with the Lower Colorado River Authority, told AccuWeather National Reporter Bill Wadell.
"Along with that, you have a lot of your hills and valleys that go along with that type of topography, and these hills don't contain a lot of soil; they have very thin soil. So when rain does hit them, not much of it gets absorbed," Rose said, noting that water will rush down the valleys and pile into creeks and streams.
Warm, moist air from the Gulf of Mexico helps fuel storms as well, giving them ample moisture to dump lots of rain in a short amount of time across the dusty Texas soil.
Joggers run near the White Rock Lake spillway during a rain shower Monday, June 7, 2021, in Dallas. Passing rain storms caused flash flooding warnings in North Texas due to an already water-saturated area that has seen record rainfalls. (AP Photo/LM Otero)
Flood experts believe that the future will bring an increased risk of flash flooding to this already flood-prone area, as more development in the region creates more impermeable surfaces and thus more runoff. Bigger storms, enhanced by a changing climate, may also lead to more flash flooding as a warmer atmosphere allows storms to hold more water.
Cities such as Austin have been taking preventative measures to warn locals about the threat of flash flooding, putting up signs in areas that flood frequently. Austin also has the Flood Early Warning System, a network of rain gauges, barricades and cameras that monitor the threat of flooding in the city.
"We're in a very, very flash flood-prone area, not only of Texas but out of the country and even the world," Rose said.
Reporting by AccuWeather's Bill Wadell
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