Meteorologists explain how the flash flooding in central Texas got so bad
Experts told ABC News that a combination of meteorological conditions made possible the days-long system that brought heavy rain and flash flooding to central Texas.
John Nielsen-Gammon, professor of meteorological sciences at Texas A&M University and Texas state climatologist, told ABC News that an upper-level disturbance in the atmosphere contributed to the storm system sitting primarily over the Texas Hill Country.
The “unusually strong” upper-level ridge allows the system to have a fully clockwise circulation, parking it over the region, Nielsen-Gammon said.
MORE: Heavy rain prompts flash flood emergency alerts in Texas Hill Country
The disturbance then combined with a mesoscale convective vortex, a warm low-pressure circulation that pumped moisture from the tropical air mass in the Gulf, causing the system to dump heavy rain on the region for several days, Marshall Shepherd, director of the Atmospheric Sciences Program at the University of Georgia and former president of the American Meteorological Society, told ABC News.
“It’s really an ideal setup in terms of rain production,” Shepherd said.
Darren Abate/AP Photo – PHOTO: Members of the Boerne Fire Department rescue a woman from floodwaters on July 15, 2026, in Boerne, Texas.
Nielsen-Gammon said a lot of moisture came into the state of Texas in July due to the low-level jet stream from the western Gulf of Mexico.
The Pacific also produces monsoon moisture and cold air masses from the north, which combine to cause extreme precipitation events.
MORE: More sweltering heat and flash flooding expected across the country
Heavy rain that began Tuesday in the Texas Hill Country continued through Wednesday and Thursday, prompting multiple flash flood warnings on waterways such as the Guadalupe River and Pedernales River.
Rainfall totals exceeded 2 feet in some areas, Nielsen-Gammon said.
Map Tiles from Google Earth – PHOTO: Flash floods hardest hit areas in Texas
Nielsen-Gammon said the storm, which killed at least 133 people over the Fourth of July weekend last year, was “very spectacular” and received heavy rainfall in a short period of time. This storm had less intense but longer-lasting precipitation and was larger geographically, with flash flood watches up and down the I-35 corridor, including the Rio Grande and the Texas plains, Shepherd said.
Additionally, Shepherd said early hydrographs indicate river levels may be higher this year.
“From a meteorological and hydrological perspective, it could be much more extreme than the 2025 flood event,” Shepherd said.
MORE: History of ‘Flash Flood Alley’, rugged area prone to flash floods in Texas
But because the flood took longer to develop, Nielsen-Gammon said it may have given people more time to “take action and protect themselves.”
Two people died due to flooding on Thursday, according to Texas Governor Greg Abbott.
“Hopefully we’ve learned some lessons and people have more plans and know what to do,” Troy Kimmel, a retired professor of meteorology at the University of Texas and emergency management incident response meteorologist, told ABC News.
Joel Angel Juarez/AP Photo – PHOTO: Flooding blocks on G Street along the Guadalupe River, July 16, 2026, Kerrville, Texas.
The Texas Hill Country is one of the regions of the United States most at risk of flooding. The area known as “Flash Flood Alley” is susceptible to dangerous floods due to its landscape as well as weather conditions. Texas Water Resources Institute (TWRI).
The “street” has steep terrain, shallow soil, and repeated high rainfall events.
MORE: Camp Mystic says it won’t reopen Texas camp this summer
According to TWRI, much of the region, which stretches from Dallas to San Antonio and encompasses the Colorado and Guadalupe River basins, lies in a highland floodplain, funneling precipitation into rivers and streams and causing them to rise rapidly.
“From a geography standpoint, it makes this area absolutely beautiful. That’s why people love it here, why we have so many campers along the rivers and streams, in the hilly terrain,” Kimmel said. he said. “But frankly, having these major events back to back makes it that much more dangerous.”
Joel Angel Juarez/AP Photo – PHOTO: Water flows along the Guadalupe River in Center Point, Texas, on July 16, 2026.
Kimmel also said that thin layers of clay soil with subsoil layers of limestone underneath do not absorb moisture.
“You have shallow soils and deep canyons, which allows floods to develop very quickly and be dangerous,” Nielsen-Gammon said. he said.
