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And Now Your 7-Day Forecast: What It Takes To Predict The Weather47:09
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Dale Earnhardt Jr. delivers a surprise seven-day forecast at a Charlotte news station ahead of weekend NASCAR race in Martinsville to help launch Goodyear's new WeatherReady tire on Friday, Oct. 27, 2017, in Charlotte, N.C. (Jason Walle/AP Images for Goodyear)
Dale Earnhardt Jr. delivers a surprise seven-day forecast at a Charlotte news station ahead of weekend NASCAR race in Martinsville to help launch Goodyear's new WeatherReady tire on Friday, Oct. 27, 2017, in Charlotte, N.C. (Jason Walle/AP Images for Goodyear)

With Meghna Chakrabarti

What does it take to predict tomorrow’s weather today? We take a look at the fascinating story behind the history and science of the weather forecast.

Guests

Andrew Blum, writer and journalist. Author of "The Weather Machine: A Journey Inside the Forecast." (@ajblum)

Bri Eggers, meteorologist at Boise’s NBC affiliate, KTVB. Member of the American Meteorological Society and attended the annual conference in May. Member of the National Weather Association. (@BriEggers)

From The Reading List

Excerpt from "The Weather Machine" by Andrew Blum

From The Weather Machine by Andrew Blum. Copyright © 2019 by Andrew Blum. Reprinted courtesy of Ecco, an imprint of HarperCollins Publishers.

NPR: "How The Advance Weather Forecast Got Good" — "Today, you can pull out your phone and know the weather a week in advance.

"That's pretty neat. And it's all because weather forecasting — specifically, the supercomputer-driven modelling which crunches huge amounts of data and predicts future outcomes — has gotten really good. A six-day weather forecast today is as good as a two-day forecast was in the 1970s.

"Andrew Blum wanted to know how those forecasts got made, and his curiosity led him to research and write The Weather Machine: A Journey Inside the Forecast. He says he first got the idea for the book when he saw a forecast for Hurricane Sandy eight days in advance of its arrival.

"'That length of that time just seemed astonishing to me,' Blum says. 'And it also seemed crazy to me that it wasn't the expert hurricane forecasters, you know, sort of putting the pieces together in their minds — it was really the outputs of these computer models that they are responding to.'

"In an interview, he explains the international network of forecasting systems — and the threat that privatization poses to that network."

New Yorker: "Why Weather Forecasting Keeps Getting Better" — "At four-fifteen on the morning of June 4, 1944, Group Captain James Martin Stagg, a meteorologist for the British military, arrived at the library of a grand manor house on the southern coast of England. On the other side of the room was General Dwight D. Eisenhower, the supreme commander of the Allied Forces—the man Stagg needed to convince that D Day should be postponed.

"The conditions for the launch had to be just so: a full moon for visibility, low tides to expose the underwater German defenses. That left a narrow window of just three days in June, and June 5th was the date the generals had settled on. But the Allies’ warships and aircraft would also need calm seas and clear skies, and here Stagg and his team had foreseen a problem.

"Even though the skies outside promised a bright morning, the meteorologists calculated that a parade of storms was poised to barrel across the Atlantic, hampering the prospects of success. The generals were wary of any delay, but Eisenhower reluctantly agreed to hold off.

"A few hours later, Stagg had better news. Allied weather stations were reporting a ridge of high pressure that would reach the beaches of Normandy on June 6th. The weather wouldn’t be ideal, but it would be good enough to proceed. Eisenhower gave the order to reschedule the invasion.

"It’s hard to overstate the importance of that weather forecast, as John Ross makes clear in a book on the subject. Had the Allies gone ahead as planned, the invasion probably would have failed. Had they postponed it until the next interval with favorable moon-and-tide conditions, they would have lost the element of surprise. The German meteorologists had also foreseen the storms, but they’d missed the significance of the brief glimpse of calm. They were so confident that an Allied attack was impossible that Field Marshal Erwin Rommel, the commander of the Normandy defenses, decided to take a few days’ leave for his wife’s birthday. He’d even bought her a new pair of shoes in Paris for the occasion. Years later, when Eisenhower was asked why D Day had been a success, he reportedly said, 'Because we had better meteorologists than the Germans.' "

Slate: "The Weather Is Worse, but Forecasts Keep Getting Better" — "Nothing is more banal than talking about the weather. But talking about weather forecasts? Pretty interesting, as it turns out. Who makes them? From what data? And what does it mean for your beach day on Friday, or for New Orleans on Saturday, where a slightly different path for Tropical Storm Barry could have huge consequences? On Wednesday, I called up Andrew Blum, author of The Weather Machine: A Journey Inside the Forecast, to talk about how sophisticated weather models are changing the way we manage everything from baseball games to evacuations. In his previous book, Tubes, Blum explained the infrastructure of the internet. In the current one, he turns his eye toward the satellites, equations, and algorithms—and, yes, humans involved at every step of the way—creating the forecast. Our conversation has been edited and condensed for clarity."

Stefano Kotsonis produced this hour for broadcast.

This program aired on July 18, 2019.

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