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A woman holding an umbrella walks down a rainy Bourbon Street in the city of New Orleans.
More lead time for storms like Hurricane Barry—which headed for New Orleans this month—gives cities more confidence to prepare.
Emily Kask for The Washington Post via Getty Images

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How better weather forecasts are changing the way cities are run

It’s not just about predicting the weather, but what cities do with the information

For someone who has spent the past several years researching and writing an entire book about how weather is forecasted, you’d expect Andrew Blum to be a jaded meteorological observer who’s seen it all. But an accurately predicted heat wave still makes him giddy.

“How weird it is that we predict the future every day and we’re so accustomed to it?” he says. “Last Monday afternoon, everyone all at once was like, ‘Did you hear it’s going to be almost 100 on Saturday?,’ like that was just a normal thing to know. And then it was!”

Blum’s book, The Weather Machine: The Journey Inside the Forecast, is essentially about predicting the future—and how we’re getting better at it all the time. Thanks to new modeling capabilities and global information systems that most of us take for granted, the six-day forecast on you can see on your phone today is as good as a three-day forecast delivered on the local news in the 1980s.

“Meteorologists and weather model-makers love to point out that their forecasts have improved about ‘a day a decade,’” says Blum, who explored another seemingly invisible network that has changed everyday life in his first book Tubes: A Journey to the Center of the Internet.

The past decade has also seen a heightened cultural awareness around the accuracy of weather forecasts—and backlash when they don’t deliver. Blum’s book opens with him holed up in his Brooklyn apartment with his six-week-old baby and the tense, drawn-out anticipation for Superstorm Sandy, along with the hashtags, the memes, and the anchors in parkas monitoring ExtremeSandyStormWatch 2012™.

“The combination, first of cable news and then of Twitter or social media in general, adds to everything else a certain hysteria,” he says. “That’s had an impact on how people see storms coming. But not only is there more hype farther in advance, the forecast is likely to be more right farther in advance.”

Yet as the forecast improves, the effects of extreme weather are getting worse. Climate change is making these types of catastrophic events more frequent and more powerful, putting more people into the paths of deadly storms, floods, and heat waves.

“Longer-term forecasts aren’t just about meteorologists’ bragging rights,” says Blum. “They give people more time, and more confidence, to make decisions.” So it’s not just about predicting the weather anymore: What cities choose to do with the information is what counts, he says. “The forecast is only as good as the decisions you make from it.”

How cities save lives during extreme weather events

The increase in lead time before potentially dangerous events has given weather agencies much more time to communicate risks to residents. Hurricane Harvey, which hit Houston in 2017, ended up dropping a record-breaking 51.88 inches of rain on parts of the city. A dire warning issued by the National Weather Service that conveyed the severity of the predicted rainfall long after the hurricane made landfall was credited with saving lives.

But more time is only part of the equation, as illustrated by Hurricane Katrina striking the Gulf Coast in 2005. “We had a pretty good two, or two-and-a-half, day forecast,” says Blum about Katrina. “Technically speaking, that was excellent for the time: It was better than average for the previous decade of hurricane forecasts.”

Yet even though the forecast gave enough time for a mandatory evacuation to be declared, the storm caused at least 1,000 deaths in New Orleans. Clearly it wasn’t enough, says Blum. “Not for a proper evacuation, with all the complexity that entailed,” he says. “The lasting lesson about Katrina is that there’s only so much that knowledge can do for the most vulnerable people trying to get out.”

With more accurate forecasts, local agencies are now able to make better decisions that protect human lives, like opening floodgates ahead of large downpours, or powering down utility lines on dry, windy nights to prevent wildfires, as California plans to do this summer.

The deadliest disaster for cities are heat waves, which, luckily, provide plenty of lead time, as heat patterns can be detected much farther in advance than storms. But even with that knowledge, city leaders face bigger, more unknown challenges as heat waves become longer and more intense due to climate change. Widespread power outages, for example, could leave parts of cities without AC.

“The perfect forecast does not solve our problems,” says Blum. “It doesn’t make it cooler.”

Forecasting what the weather does, not just what the weather is

Last winter, when a blizzard was forecasted to potentially incapacitate the New York City metropolitan area, city leaders made a 6 p.m. decision to close schools the next day. Only flurries fell, angering parents who had to scramble for last-minute child care or stay home from work with their kids.

“The implication was that the forecast was wrong,” says Blum. In fact, he says, officials made the call when the the forecast was still a few hours from certainty.

This new method of predicting what the weather will do to people and places, rather than just what the weather will be, is called “impact-based forecasting,” and it can provide cities with a timeline to prepare for larger implications brought on by weather events—right down to the hour and the exact location they start to effect communities, in some cases.

Cities might use impact-based forecasting to preemptively cancel citywide events, like New York City did with the snow day, and also what many cities did before last weekend’s heat wave, but these decisions also run the risk of being wrong and potentially very costly.

When impact-based forecasting works, however, the result is almost like time travel, says Blum. Last spring, after local forecasts for Augusta, Georgia, showed rain starting at 3 p.m. with thunderstorms at 5 p.m., the Masters golf tournament being held there was moved earlier in the day. The entire day was restructured so players would be finished by the time the rain started. It arrived right on schedule.

Now the public weather forecast may be at risk

Predicting the future relies not just on revolutionary technology but also on a massive open data infrastructure where meteorologists have shared their observations for 150 years. Much like other multinational agreements that govern trade or health, weather data is distributed freely among public agencies.

But what if one powerful entity stops sharing its information? “As soon as you have governments getting data from private sources, you begin to chip away at the global foundation,” says Blum.

This could be starting to happen in the U.S. The Trump-appointed head of the National Oceanic and Atmospheric Administration (NOAA) is the former CEO for AccuWeather, which charges clients for its forecasts.

A privatized weather system could further disrupt the delicate choreography between local meteorologists, regional forecasting offices, and city emergency managers, who work together to create disaster alerts for residents. If all those parties don’t have access to the same data, cooperation becomes more difficult.

Take a hypothetical hurricane barreling towards Southern Florida. Some apps might offer more accurate, impact-based forecasts to the users who have paid premium prices, says Blum. “Who has access to that forecast—and who evacuates Florida first?”

In a world of supercharged storms, a private prediction network creates an even more dystopian future for cities. It’s not just an accurate forecast that matters, but also an accessible one.


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