These are the factors that contributed to the extreme Texas flooding
A "worst case scenario" of meteorological events combined with dryness and topography of the landscape in central Texas contributed to the weekend's extreme flash flooding event that killed dozens of people in the region, according to reports.
On Friday, torrential rain pounded the region, causing the Guadalupe River in Kerr County to rise 26 feet in just 45 minutes -- the second-highest on record, officials said .
This is what led to the flash flood emergency:
The weather patterns
"Extraordinary" rainfall rates of 2 to 4 inches per hour in some areas -- such as Kerr County and Mason County -- equated to up to 18 inches in some spots, according to measurements from the National Weather Service (NWS).
"That volume of water falling over relatively short periods of time -- that's a disaster waiting to happen," Marshall Shepherd, director of the Atmospheric Sciences Program at the University of Georgia and former president of the American Meteorological Society, told ABC News.
Atmospheric conditions in place over the Southern Plains at the time favored slow-moving thunderstorms, which increased the odds of heavy rain and flash flooding due to their ability to sit over the same area for hours.
In addition, the region favors heavy rainfall events.
The atmospheric conditions were further enhanced by an abundant amount of tropical moisture coming from several sources: the Gulf, monsoonal moisture from the eastern Pacific and remnant moisture from Tropical Storm Barry, which made landfall on the east coast of Mexico on June 29. While the weak system quickly dissipated as it tracked inland, its remnant circulation continued to quietly linger up north toward the Texas-Mexico border, bringing some tropical moisture from the Bay of Campeche up to Texas.
An extremely high level of atmospheric moisture over the region provided ample fuel for persistent torrential rain and extreme totals.
There were "some very clear meteorological signals," such as a tilted trough and a mesoscale convective vortex, that contributed to the extreme precipitation, Shepherd said.
The mesoscale conductive vortex essentially spun the remnants of a tropical system, causing significant ascent or rising motion to activate that moisture into condensation and precipitation in an efficient manner, according to Shepherd.
As a result, there were "very extreme" precipitable water values, which is the measure of how much water would contend to be rained out of a column. It's one of the "telltale signals" that meteorologists look for in flooding events, he noted.
"Those are sort of the worst case ingredients, from a meteorological standpoint," Shepherd said.
The region is prone to flash flooding
The complex terrain of the hilly community exacerbated the emergency, Shepherd said.
Texas Hill Country is often colloquially referred to as "Flash Flood Alley" because the weather and landscape in the south-central Texas region work together to produce rapid flood events, the Texas Water Resources Institute (TWRI) noted.
Flash Flood Alley is known as one of the most flood-prone regions in the U.S. due to its high susceptibility to flash flooding with steep terrain, shallow soil and repeated high rainfall events. The Guadalupe River Basin is one of the three most dangerous regions in the country for flash floods, according to the Guadalupe-Blanco River Authority.
The Gulf provides an infinite source of air over the region, making high rainfall intensities a common occurrence.
In addition, places like Hunt and Kerr Counties are situated on a floodplain between tall, rugged hills that funnel any rainfall down into rivers and creeks below. In this event, the extreme rainfall funneled into the Guadalupe River, which led to the rapid rise in water levels.
The region's rocky topography makes it especially prone to flash flooding, according to the TWRI. The type of clay-rich soil in the region contributes to the flash flooding because clay soils have low infiltration and trigger high water runoff once wet, it said.
Drought
Severe to exceptional drought conditions were prevalent for much of south-central Texas when the downpours came, according to the U.S. Drought Monitor. Kerr County has been in drought since the beginning of 2025.
Drought conditions can make areas more susceptible to flash flooding as the soil cannot absorb rainfall as efficiently. This exacerbated the higher flash flood risk that already existed in the region due to its rocky topography.
"The landscape was probably quite dry, and so anything was falling was probably running off quite rapidly, in the same way that water would run off on a paved surface," Shepherd said.
Messaging challenges
While the threat of the flooding was communicated more than a day before the rain event began, the timing of the emergency -- during the middle of the night -- may have contributed to the high death toll.
The Texas Department of Emergency Management activated state emergency response resources in anticipation of increased threats of flooding in parts of west and central Texas heading into the holiday weekend, it noted in a press release.
In addition, the National Oceanic and Atmospheric Administration included the flash flooding risk in its three-to-seven-day hazards outlook, according to Shepherd.
Flash flood warnings, including the flash flood emergency -- the highest alert for flash floods -- are distributed by the NWS in the same manner as tornado warnings: via the national EAS and WEA alert systems.
"There were indications days to hours in advance, but there's still questions about getting it across the goal line," Shepherd said.
"Normalcy bias" may have played a role as well, since people in the region are used to receiving flood warnings, Shepherd added.
"People perceive that they're used to these types of events, although their benchmarks in their minds might not prepare them for like an anomaly or a 'black swan' type of it," he said.
While there are questions about cell phone service and access for a way to receive the NWS and other emergency alerts, NOAA Weather Radio All Hazards (NWR), which are battery powered and have better nationwide coverage reliability than cell service, are a long-standing and reliable alternative highly recommend by NWS and meteorologists across the country .
NWR is a nationwide network of radio stations broadcasting continuous weather information directly from the nearest NWS office. It broadcasts official Weather Service warnings, watches, forecasts and other hazard information 24 hours a day, seven days a week.
Every camper and camp -- as well as every person in the country -- should have a NOAA radio, ABC News Chief Meteorologist and Chief Climate Correspondent Ginger Zee said.
"This is battery powered and will wake you from a dead sleep," Zee said. "The timely warnings from NWS that night can be programmed to go off and would wake folks and give them at least a few minutes, if not longer, to seek higher ground."
With a NOAA weather radio, a flash flood warning would have blared around 1:14 a.m. local time, about three hours in advance of the catastrophic flooding, Zee said.
The weekend flooding killed at least 94 people -- many of whom were campers and counselors from Camp Mystic, a Christian girls camp situated on the Guadalupe River.
At least 11 campers are still unaccounted for, officials said on Monday.
"This terrible tragedy highlights why policymakers need to continue making robust investments in science-based weather and climate models and forecasts, alongside investing in a robust local emergency alert system and disaster response and recovery," Rachel Cleetus, policy director and lead economist for the climate and energy program at the Union of Concerned Scientists, told ABC News.’
"We won't be able to completely eliminate every risk, but we cannot let reckless cuts to critical agency functions, including NOAA and FEMA, put more people in danger especially as climate change fuels worsening disaster," Cleetus added.
One of the "clearest impacts" of climate change will be more frequent heavy rainfall events, like what happened in Texas over the weekend, Jennifer Francis, an atmospheric scientist at the Woodwell Climate Research Center, told ABC News.
