The snow gods: How a couple of ski bums built the internet’s best weather app

Bryan Allegretto and Joel Gratz, two ski-obsessed meteorologists, built OpenSnow, an independent weather app that has become the snow-forecasting standard for skiers and snowboarders worldwide, outcompeting federal weather services with hyperlocal predictions. Allegretto started manually entering snowfall data for every ski resort in 2006 while working his day job, eventually merging his Tahoe Weather Discussion site with Gratz's Colorado Powder Forecast in 2010 for zero initial pay. The pair automated their operation around 2018 by building METEOS, their own proprietary weather model that ingests government data and satellite information, then applies decades of alpine experience to fix forecast errors that generic weather models produce. OpenSnow grew from a 37-person email list to a half-million-strong following and has proved invaluable during an unusually volatile winter—the US West saw little snow despite intense storms and deadly avalanches, while the East received heavy, sustained snowfall. The app's forecasters, who have become minor celebrities in skiing culture, now analyze data to produce "Daily Snow" reports for locations worldwide and are expanding into avalanche prediction.