(Wired) Californians are drying their socks, draining their basements, and de-flooding their freeways after a massive rainstorm drenched the state late this week. The brunt of the downpour came on Dec. 11, when an average of 2.5 inches of rain fell across the state.
The rain came via a tributary of atmospheric moisture that snaked its way up from the tropics near Hawaii. Historically, this transport of wet air isn't uncommon—the phenomenon is nicknamed the "Pineapple Express"—and is typically responsible for about 30-50 percent of the annual precipitation in the dry western states. This storm was particularly dramatic, as it came in the midst of the state's current three-year drought.