What should you do in the face of a flash flood?
The question is on the minds of many in the wake of catastrophic flooding in Texas, which has killed over 100 people and renewed scrutiny over state and federal emergency preparedness.
While the July 4th floods broke records, Texas is not alone. Flash floods have devastated communities across the country in recent months, from the South to the Midwest.
Flash flooding usually starts within three to six hours of heavy rainfall from hurricanes and thunderstorms, but can also follow a dam failure or melting ice. It can start with very little warning and escalate exponentially, with currents powerful enough to carry away cars and other debris.
And climate change is making them worse, as a warmer atmosphere can drop more intense rain over shorter periods of time.
Jonathan Sury, a senior staff associate at the National Center for Disaster Preparedness at Columbia University's Climate School, says the flooding in Texas — whose scope and speed caught many off-guard — is an example of a tragic trend.
"This is a warning sign, in a way, to many other communities, specifically in rural areas, that these types of events may happen and are becoming less rare," he says.
Sury notes that the Texas floods are also one of a number of extreme weather events that happened in the middle of the night, while many people were asleep. Those include a string of deadly tornadoes that swept through Kentucky in May, and some of the wildfires that ravaged Los Angeles in January.
This kind of overnight emergency, Sury says, "requires a different level of preparedness and a different level of awareness."
Here's some expert advice for how to protect yourself from flash floods — a process that starts well before storm clouds appear.
Before a storm
Sury says bracing for a weather event starts with having a solid household emergency preparedness plan.
To make one, you first have to understand your level of risk. You can use tools from FEMA and First Street Foundation to figure out what flood zone your home is in and what that means for evacuating.
For example: What is the closest higher ground you can get to, what route would you take and what areas might be susceptible to flooding along the way? Is there an attic or upper floor that people can move to without having to go outside? Where will your family members meet if they get separated?
Once you have that plan — and share it with every member of your household — you should pack a go bag with things such as water, food, medications, laminated copies of important documents and phone numbers, cash, first-aid supplies, signaling devices and an ax. Sury recommends keeping a smaller, separate emergency bag in your vehicle too.
"Doing that preparedness well before something happens is what's really going to make people more at ease," Sury says. "These events are very stressful and people are able to make better decisions in a time of crisis when they aren't fumbling around to find X, Y or Z."
The next step is to set up multiple ways of receiving weather alerts, and understand what different warnings mean.
There is a nationwide emergency warning system that will ping your phone with weather threats (just make sure your phone settings allow you to get notifications), but you can also sign up for alerts from your local weather and news channels. You can also buy a physical NOAA weather radio, which broadcasts round-the-clock forecasts and warnings from the National Weather Service.
Pay attention to the language of those alerts: A flash flood watch means conditions are favorable for one to happen, while a flash flood warning means flooding is imminent or already happening.
"The flash flood warning, when you see that, that's the time to really think about: How can I get to higher ground?" Sury says. "And if I'm in my car, how can I get to higher ground as well as not wanting to drive through an area that often floods?"
During a storm
Once a flash flood starts, experts say the main priority is quickly getting to higher ground, whether that's the top floor of a building, the roof of your house or the highest hill in the woods.
If you evacuate your home, you should try to turn off your utilities and place valuables on the highest floor. And if you're outside — by coincidence or choice — you should never try to walk, swim or drive through the water.
Flash floods can come on in minutes, and even small amounts of fast-moving water can be extremely dangerous, says Jennifer Horney, with the Disaster Research Center at the University of Delaware. Floodwaters may also contain hazardous household chemicals, waste and debris.
"It only takes 6 inches of water to sweep away a person who's walking and only 1 to 2 feet to push away a car or a truck," Horney told NPR's Morning Edition. "So even if you have that big SUV, don't try to drive through a flood."
The best advice, as the National Weather Service says, is to "turn around, don't drown." If you see a flooding or low-lying road, turn your car around and either pull over or drive in the opposite direction.
If you do find yourself in a car taking on water, you should try to get out as quickly as possible. Undo your seatbelt and climb out through the windows before the car gets totally submerged.
"Losing your vehicle is much more easy to replace than losing your life," says Stephen Wood, an associate professor at Northeastern University's nursing school who has worked in emergency medicine.
Wood — who once escaped a flash flood in the New Hampshire mountains — says everyone should have something in their car that can cut their seatbelt and break a window (you can buy "car escape tools" made for this). Aim for the corner of the window, which is the weakest part of the glass.
If you do find yourself in the water, Wood recommends trying to float on your back and position yourself feet-first to take the majority of any impact from debris. If you hit or pass by something you can grab on to — like a tree — try to climb up and away from the water.
He emphasized the importance of an evacuation plan and go bag, though said people should also be prepared to make decisions in the moment based on their surroundings: "I think it's instinctive survival."
Once you're on higher ground, you can call for help — but keep in mind that even if your phone is working, you may not be the only one dialing 911. Standing on a roof or next to a car can make you more visible to first responders when they do show up.
"The good thing about the flash floods is that they tend to dissipate quickly, and there are special teams trained to rescue people in swift water situations," Horney said.
After a storm
Even after the storm passes, danger can persist.
Wait for emergency workers to remove any downed power lines and debris, and for authorities to issue the all-clear, before returning back to your street, let alone your home.
At home, check for things like damaged gas lines, cracked foundation and standing water to make sure it's safe to go inside. Wear protective gear, like goggles and sturdy shoes.
Once inside, check to see how high the water levels got and whether they reached the height of electrical sockets — and if so, don't plug anything in just yet. Sury also recommends looking out for mold, which can live behind walls. You can hire experts to evaluate your home and any potential repairs.
As NPR has reported, if your house flooded, you should take steps to dry it out immediately, including ripping up carpets and removing furniture. It's also crucial to take pictures of the damage of the inside and outside — especially the water levels — for insurance and assistance purposes.
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