When heavy rainfall occurs in a short period of time, rushing water can deluge homes and basement apartments, overtake cars and knock people off their feet. Flash floods can develop quickly, within hours or even minutes; and they often catch people off guard, killing an average of 88 people in the United States each year.
“Flash floods occur when there’s just too much water coming in too fast,” said Bonnie Schneider, a meteorologist and author of “Extreme Weather.” And climate change is compounding the risks: Warmer air holds more moisture, Ms. Schneider said, which can lead to heavier, more intense rainfall.
Though flash floods are scary, experts say you can increase your odds of survival by staying informed and having a plan. Here’s what to do in advance — and in the moment — to get through a flash flood safely.
Understand the difference between the various alerts.
The National Weather Service currently issues severe weather alerts in English and Spanish.
If there’s a “flash flood watch,” according to the service, flooding is not guaranteed, but conditions are favorable enough for it to be possible, so be prepared to change your plans.
A “flash flood warning” means a flash flood is imminent or already occurring, and you should immediately move to higher ground if you’re outside or in a basement apartment.
The most dire alert is a “flash flood emergency,” which indicates that not only is flooding occurring, but it’s posing a severe threat to human life. In 2021, New York City received its first notification of this type during heavy rainfall caused by Hurricane Ida.
Before a flood
Make a plan
Long before rain is on the radar, the first step is to come up with a plan for how your family will communicate, meet and evacuate if there’s a flash flood emergency. How will you escape from your home if needed? Who will be responsible for the kids? Where will you meet if your family becomes separated? The American Red Cross has printable templates to help guide your conversation.
You’ll also want to evaluate the flood risks to your home, work and school, as well as the routes between them. The flood maps developed by the Federal Emergency Management Agency are a good place to start. (If you live in a flood zone, you might also want to consider purchasing flood insurance.)
Prepare a ‘go bag’ now
If you need to leave your home in a hurry, it’s crucial to have an easily accessible emergency kit packed with supplies. Consider adding shelf-stable food; water or a portable filtration system; a change of clothing; a headlamp or flashlight with batteries; a phone charger; face masks; cash; and a first-aid kit. If you have pets, don’t forget food, leashes and portable bowls for them, too. Ready.gov also advises creating “password-protected digital copies” of important paperwork, like birth certificates, identification cards, insurance policies, wills, deeds and titles.
If this seems like overkill, it’s not, said Dr. David Markenson, chief medical officer at American Red Cross Training Services. “The human nature side is obviously not to worry,” he said. And many people think, “‘It’s not going to happen to me.’”
But having a plan can help you make better choices in an emergency, said Sabine Marx, a senior trainer at Columbia University’s National Center for Disaster Preparedness. As she described it, she wouldn’t want to “have to come up with this decision on the spot when I’m also possibly fearing for my life.”
During a flood
If a storm is in the forecast or underway, pay attention to local weather alerts via your phone, radio or TV. In the case of a power outage, a battery-operated radio can come in handy.
Be prepared to evacuate
If there’s a chance you may have to evacuate, gather essential items that are not already in your go bag — driver’s licenses, credit cards, medications and key documents — and seal them in a waterproof pouch. (A plastic freezer bag works just fine.) Make sure your phone is charged and, if you have time, unplug small appliances so they won’t get fried by electrical surges. Move valuables to a higher floor (if you have one).
If you live in a basement apartment, be extra vigilant when it comes to monitoring rainstorms, said Julie Munger, founder of Sierra Rescue International, an organization that has trained swift-water rescuers for 35 years. If you believe you may be in danger, she recommended immediately moving to a higher floor or evacuating to another location. (To find an emergency shelter, text SHELTER and your ZIP code to 43362.) FEMA warns against climbing into a closed attic, as you could become trapped by rising floodwaters. If necessary, climb onto the roof.
If you find yourself in the worst-case scenario, with water rushing into your apartment, you need to act fast, Ms. Munger said. “Don’t wait, don’t grab anything, just exit,” because if you can’t get out, she added, your only option is to “hope that the water doesn’t fill up the apartment completely.”
According to Dr. Markenson, it’s essential to follow updates closely, since conditions can change rapidly. If you’re told to evacuate, do it. Check road closures on your state’s department of transportation website before heading out if there’s time, and take an alternate route if you encounter a flooded road.
The biggest issue with flash floods, Dr. Markenson said, is that people don’t always evacuate when they’re told to do so. But by trying to ride it out, he warned, you’ll endanger yourself and rescuers.
Avoid floodwaters when possible
The best thing to do is avoid all floodwaters if you can — or, as the National Weather Service’s grim catchphrase urges: “Turn Around Don’t Drown.” It takes just six inches of fast-moving water to knock you off your feet, so unless you’re ordered to evacuate, staying where you are is usually the safest choice. (Flash floods generally pass quickly.)
The most immediate risk of entering floodwaters is drowning, but you may also expose yourself to various harmful things floating around the water itself, like human, animal and industrial waste; physical objects like cars, lumber and other debris; stray animals like rodents and snakes; and downed power lines.
If you’re caught in your car
Sometimes flash flooding happens when you’re out and about, and you may suddenly find yourself in a life-threatening situation. Nearly half of all flash flood deaths are vehicle-related, which is why you should never ignore barriers. “Don’t drive into a flooded street, period,” Ms. Munger said. “There really is no better advice.”
Not only is it difficult to gauge water depth and road conditions, but just 12 inches of water can float your car and 18 inches can carry off your SUV or pickup truck. “Everybody tends to underestimate the force of the water,” Ms. Munger said. “It takes very little current to wreak havoc.”
That said, if your car does get taken by floodwaters, first, roll down your windows, said Lynn Burttschell, an emergency medical worker, rescue swimmer and founder of Wimberley Rescue Training. If they won’t budge, he recommended breaking the glass with an escape tool (like the one in this Wirecutter guide, which you can store in your glove compartment) or using the metal pole of your headrest as a ram. It’s important to open the windows, Mr. Burttschell said, because “if the water continues to rise, then that car fills up and becomes more of a rock instead of a bobber floating downstream.”
Then, unbuckle your seatbelt and grip it as you climb onto the roof and call 911, Mr. Burttschell advised. Do your best to remain with the car until help arrives. Lie down on the roof to keep yourself stable, and don’t tie yourself to the car, in case it rolls.
During his 32-year career, Mr. Burttschell has found that people who stay with their cars survive at much higher rates than those who abandon them, simply because it’s easier for emergency services to spot a vehicle than a person. “I really don’t ever recommend leaving the vehicle,” he said. To make yourself more noticeable, you can also turn on your hazard lights, activate your car’s alarm with your key fob and, if possible, honk the horn.
If you’re walking, hiking or camping
If you happen to get caught in a flash flood while on foot, run perpendicular to the water and “get to the highest point possible,” Ms. Munger said — whether that means heading into the nearest building and racing up the stairs, climbing a tree or clambering onto a truck. The bigger and heavier the object, the better, she said, since it will be less likely to float away.
If you do get swept away, don’t attempt to stand up, as you risk trapping your foot in a drain, fence or other object. Instead, Ms. Munger advised swimming perpendicular to the current, as you would with a rip tide, until you get to safety. Since you’ll be fighting against drainages, debris and the current, she warned this is extremely difficult, even for strong swimmers. “People need to realize that most people who lose their footing in a flash flood don’t get out,” she said.
As for camping or hiking, Ms. Munger advised researching the region’s weather patterns and forecast before setting out. If there might be a rainstorm upstream of your destination, she suggested camping above any rivers, rather than beside them. If water starts to rise where you are, head immediately to higher ground.
If you’re on an underground train or subway
The subway is “the last place you want to be” during a flash flood, Ms. Munger said. “Because eventually, if the storm drains are overwhelmed, there’s no other place for the water to go.” Your best defense, in other words, is to avoid it altogether.
If you do find yourself underground during a flood, Ms. Munger urged exiting the station as swiftly as possible — even if that means forcing your way up flooded stairs. If you’re on a train that is stuck, don’t leave it until you’re instructed to do so, said Eugene Resnick, a spokesman for the Metropolitan Transportation Authority in New York.
Take flash floods seriously
While some of these steps may sound inconvenient, the reality is that following them could save your life. “You never want to be in a position where you’re looking back, or others are looking back, and saying: ‘Why didn’t you just heed simple advice?’” Dr. Markenson said.
Or, as Ms. Munger put it: “It’s going to be much more of a hassle and much more tragic when you don’t make it home.”
Susan Shain is a freelance journalist and future New York Times fellow based in Madison, Wis.
Sept. 13, 2021
An earlier version of this article misstated the title of Sabine Marx. She is a senior trainer at Columbia University’s National Center for Disaster Preparedness, not a director of research.
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