Weather forecasts have become much more accurate. A four-day...

Weather forecasts have become much more accurate. A four-day forecast today is as accurate as a one-day forecast 30 years ago. The chart here shows the difference between the forecast and the actual weather outcome for forecasts 3, 5, 7, and 10 days in advance. The metric used here is the “500 hPa geopotential height”, a commonly used meteorological measure of air pressure — which dictates weather patterns. The solid line is for the Northern Hemisphere, and the dashed line is for the Southern. Three-day forecasts have been pretty accurate since the 1980s, and have still gotten a lot better over time. Today the accuracy is around 97%. The biggest improvements we’ve seen are for longer timeframes. By the early 2000s, 5-day forecasts were “highly accurate” and 7-day forecasts are reaching that threshold today. 10-day forecasts aren’t quite there yet but are getting better. This data comes from the European Centre for Medium-Range Weather Forecasts (ECMWF), which produces global numerical weather models and publishes analyses of its errors over time. While national weather agencies use much higher-resolution processing to get local forecasts, these global models provide a crucial input into those more local systems.

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Floehr’s analysis uncovered two big trends in weather prediction. One was toward greater relative accuracy in the private sector—which of course was totally dependent on the National Weather Service data for its forecasts. The other was the astonishing improvement in all weather predictions. The five-day-out forecast in 2016 was as accurate as the

Michael Lewis • The Fifth Risk

[OC] How reliable is the weather forecast across the US? (to within 3°F)

Forecasting is often vibes. But so is expertise

Often experts apply their knowledge in unfamiliar or uncertain situations. “How much will this policy decrease child poverty” “Will Biden leave in the next 3 days” “Will I feel better after taking painkillers?” “How much will sea levels rise?”

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The National Weather Service’s forecasts are, it turns out, admirably well calibrated46 (figure 4-7). When they say there is a 20 percent chance of rain, it really does rain 20 percent of the time. They have been making good use of feedback, and their forecasts are honest and accurate.

Nate Silver • The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

The improvements in weather forecasts are a result of two features of their discipline. First meteorologists get a lot of feedback—weather predictions play out daily, a reality check that helps keep them well-calibrated. This advantage is not available to climate forecasters and is one of the best reasons to be skeptical about their predictions, si

Nate Silver • The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

The NWS keeps two different sets of books: one that shows how well the computers are doing by themselves and another that accounts for how much value the humans are contributing. According to the agency’s statistics, humans improve the accuracy of precipitation forecasts by about 25 percent over the computer guidance alone,31 and temperature foreca

Nate Silver • The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

The bigger question is why, if these longer-term forecasts aren’t any good, outlets like the Weather Channel (which publishes ten-day forecasts) and AccuWeather (which ups the ante and goes for fifteen) continue to produce them. Dr. Rose took the position that doing so doesn’t really cause any harm; even a forecast based purely on climatology might

Nate Silver • The Signal and the Noise: Why So Many Predictions Fail-but Some Don't

The science of weather forecasting is a success story despite the challenges posed by the intricacies of the weather system. As you’ll find throughout this book, cases like these are more the exception than the rule when it comes to making forecasts.