Weather App Shows Different Forecast Than Other Weather App, Both Wrong

A man planning a weekend barbecue consulted seven weather forecasting applications, received seven different predictions, and experienced an eighth meteorological outcome that none of them had anticipated. Greg Isobar, 44, began checking weather forecasts on Monday for a Saturday afternoon gathering. The forecasts diverged immediately and continued to diverge throughout the week. Monday's forecasts for Saturday: Apple Weather said partly cloudy, 78 degrees. Weather.com said mostly sunny, 82 degrees. AccuWeather said sunny, 80 degrees. The Weather Channel app said scattered thunderstorms. Dark Sky's replacement said cloudy with a 30% chance of rain. The NWS point forecast said a slight chance of showers. Windy.com showed three different model outputs, none of which agreed. "I checked them each morning," Isobar reported. "They never converged. On Thursday, two apps switched their forecasts — one went from sunny to rain, the other went from rain to sunny. They literally traded predictions. I don't think they're looking at the same atmosphere." By Friday evening, Isobar had committed to the barbecue regardless, citing what he called "forecast paralysis" — the state of having so much predictive information that none of it is actionable. Saturday's actual weather: fog until noon, followed by two hours of sunshine, followed by a brief hailstorm, followed by a rainbow, followed by clear skies at sunset. No app predicted fog. No app predicted hail. One app, in retrospect, could claim partial credit for the two hours of sunshine. "The barbecue was fine," Isobar said. "We moved inside during the hail, which lasted eight minutes. Then we moved back outside. The apps all said 'I told you so' in different ways. None of them were right, but none of them were wrong enough to uninstall." Isobar has since reduced his weather app collection to two: one for optimistic forecasts and one for pessimistic ones. "I split the difference mentally," he explained. "It's analog ensemble forecasting."