With a warmer atmosphere expected to spur an increase in major storms, floods, and other wild weather events, scientists and meteorologists worldwide are harnessing advanced computing power to devise more accurate, medium-range forecasts that could save lives and property. Like a pipeline in the sky, the plume of sodden tropical air advanced mile-high above the Pacific Ocean, heading toward the California coast. This “atmospheric river” — a long, narrow band of concentrated water vapor — carried the moisture equivalent of about 15 Mississippi Rivers. When it made landfall, it dumped a massive amount of rain on the densely populated stretch of California from San Francisco to Los Angeles, unleashing floodwaters, causing landslides, and cutting off power to hundreds of thousands of homes and businesses. Atmospheric rivers fuel some of western North America’s most intense and destructive winter storms, and this one, slamming California last December, was a big one. […]