Why flash flood warnings are never enough

This story was originally published by Grist and is reproduced here as part of the Climate Desk collaboration.

This year’s Fourth of July was the first time that the town of Comfort, Texas, used the sirens intended to warn its roughly 2,000 residents of imminent flooding. Founded by German abolitionists in 1854, Comfort sits along the Guadalupe River in an area known as “flash flood alley.” It installed its siren-based warning system last year, a move that neighboring Kerr County, where well over 100 people died in this month’s floods, opted against.

One Comfort resident told Grist that when she heard the sirens, she had no way of knowing just how much urgency was called for.  “In my mind, I’m going, ‘Okay we’ve got a couple hours before it gets up to the house, because it’s a 50-foot drop from our house to the creek,” she said. Her husband started walking down to check on the water level, but quickly ran back inside. “You’ve got five minutes,” he told her. “Grab everything you need.’” 

Ultimately, she and her husband were lucky—they were able to shelter with a neighbor whose house is on higher ground—but their close call captures a dilemma that’s taking on new urgency as flash floods claim lives from Texas to North Carolina: Even the most comprehensive disaster warnings are only as helpful as the responses of those who receive them. 

“If you’ve never seen water rise in front of you in minutes, it’s hard to conceive of how quickly that can happen—and how quickly your life and property can be at risk,” said Rachel Hogan Carr, executive director of the Nurture Nature Center, a nonprofit focused on flood-risk communication.

“There’s barriers to warning delivery from things like internet connectivity, people not having cell phones, or being asleep when a warning comes in,” added Hogan Carr, who is also a co-chair of Integrated Prediction of Precipitation and Hydrology for Early Actions (InPRA) a working group within National Oceanic and Atmospheric Administration that researches early warning systems. “Communities need to anticipate these barriers, and set up local systems in order to amplify the distribution of warnings when they come in.” 

In the aftermath of the July 4 deluge, questions about the efficacy of local warning systems have swirled, particularly in Kerr County, which saw the most devastating flooding. Although the county had the ability to use FEMA’s Integrated Public Alert and Warning System (IPAWS), to push out aggressive, vibrating alarms to residents’ mobile phones—similar to those that sound when an AMBER alert is issued to inform residents of a given area about a missing child—that system wasn’t used until days after the flood, as more rain headed towards the area. 

That said, cellphone customers in the at-risk service area were sent a variety of warnings—including a flash flood warning from the National Weather Service—but their effects appear to have been limited. Many received no alert, or only received an alert after the flood had overtaken them. Even if the county had sent additional warnings, many residents likely would have missed them if their phones were off or out of reach for the night.

Plus, a warning from local officials may have carried more weight than the alerts from the National Weather Service, Abdul-Akeem Sadiq, a professor at the University of Central Florida who studies emergency management, told the Washington Post. People tend to be more receptive to warnings that are tailored specifically to them, added Hogan Carr.

“We saw this in Superstorm Sandy,” she explained. “Even though the entire New Jersey shoreline there was at risk, if it didn’t say somebody’s specific small town name, they often decided it [didn’t apply] to them.” 

On the night of the flooding, Kerr County resident Martha Murayama says she was woken up by an audible alert on her phone. But she turned it off without reading the warning, assuming that it was an AMBER Alert. Murayama lives in the gated subdivision of Bumble Bee Hills, which sit directly across from the Guadalupe between Kerrville and Ingram, Texas. By then, the flood was already well underway. Not long after she got back to bed, Murayama received a panicked call from her neighbor, saying that someone was banging on the door. It was a family who lived directly across from the river, trying to warn people as they moved to higher ground. Murayama was worried—her neighbor, Joe, suffers from Parkinson’s and was not in good health. When Murayama’s husband went outside to investigate, he was quickly swept away by floodwaters, although he was ultimately able to make his way back to the house. 

Just up the hill, Ramiro Rodriguez was awoken by the same family seeking shelter. Like Murayama, he too thought immediately of Joe and made his way down to the house through floodwaters to help Joe and his wife up the hill. As they managed to pop the garage door open, Rodriguez spotted a tow strap, which he used to haul the couple to his house. “I tied up Joe to my hips,” he said. “And right about that time, you can hear the flash flood warning.” 

But just as quickly as the water arrived, it receded. Since July 4, Murayama says, she’s gotten new flood alerts constantly. 

Flash floods are among the deadliest natural disasters and the most difficult to accurately predict. Less than 1 percent of waterways across the United States have stream gauges that monitor rising water in real time; the National Weather Service often relies on computer modeling to assess flood risk in smaller creeks and streams. (Kerr County only has six river gauges, which makes predicting floods more difficult).

But nearby development can quickly render these models outdated. For example, a stream bordered by concrete will flood much faster and cause much more damage in the surrounding community than one that runs alongside a park, which has natural features that can absorb water. 

Even when floods can be anticipated, communicating their severity to the public is a tall order. Because flash floods are very localized, even neighborhood-level warnings may seem like false alarms to some residents, leading to what the journalist Zoë Schlanger has dubbed “alert fatigue.”

That’s why early community education is such an integral part of a functioning warning system, according to Hogan Carr. “If you get a flash flood warning and you never see it, you got lucky,” she said.

Many people do not understand the speed with which floods move, which can lead to them driving through areas that are about to be submerged, for example. Warnings such as the ones sent in Texas, encouraging residents to “move to higher ground,” don’t necessarily convey urgency, according to Ashley Coles, an associate professor of environmental geography at Texas Christian University who studies flash flooding.

“I spoke to somebody regarding the flooding in Texas. They said, ‘You know, if I had gotten that message I would’ve gotten together a go bag and then gone to bed.’ So they would have been ready to evacuate if needed, but it came so fast that they would have been swept away,” said Coles. “It makes it very difficult even for people who are trying to be cautious.” 

The National Weather Service has defended its response to the floods, pointing out that it issued warnings at 1:14 am, two hours before the flood waters reached inhabited riverside areas like Camp Mystic. But the warnings, though they cautioned that “life-threatening” flooding was possible, did not order evacuations.

As climate change makes flash floods and other extreme weather events more common and deadly, researchers across the country are struggling with how to effectively communicate risk to the public, without losing their trust through over-warning.

”It has to be really a comprehensive strategy of community support, wrapped around the issuance of a formal flood warning,” said Hogan Carr, explaining that ideally, the local weather service would have a forecaster whose job was dedicated to doing community outreach, explaining local risks, where forecasts come from, and where residents can get reliable information in an emergency. “It’s an investment of time and resources proactively, that could pay off tremendously during these large-scale events,” she added.

In the meantime, Kerr County residents are hoping for a siren system, like the one used in neighboring Comfort. “I slept through [the phone alert],” said Rodriguez. “If it wasn’t for those people knocking on the door, I would have slept right through it.”