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

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 dec...