What's Causing California's Worst Drought in Centuries?

It rained for about five minutes yesterday and Southern California might get a few more drops this weekend, but California is still in a very-bad-and-getting-worse drought. In fact, the state has been in a drought for a long time now and might be headed for a megadrought. That's not as scary as it sounds! Jk, yes it is. "One of the most persistent and intense ridges of high pressure ever recorded in North America has been anchored over the West Coast since December 2012," according to meteorologist Jeff Masters at WunderBlog, which is what made 2013 California's driest year on record. Once in a while the ridge breaks and allows a low pressure system in, causing a storm, but it "inevitably builds back after each storm, clamping down on any moisture reaching the state." Masters says that models show the ridge is on its way back up again (although it probably won't be as strong) and there won't be any more significant precipitation in the state for at least a week. (The high pressure ridge is just part of a weather pattern over the Northern Hemisphere that's also causing the Polar Vortex.)

The Sierras, an important source of water in California, got about two feet of snow this week, but snowpack up there is still at its lowest level in more than 50 years; a survey yesterday found it's now at 12 percent of its average level.

This drought is part of a larger, 14-year drought in the Western US, which peaked between 2000 and 2004, the droughtiest years since "the last mega drought over 800 years ago." (We've already learned that the twentieth century was unusually wet in California.) A 2012 study thinks those conditions "will be the new normal in the Western U.S. by 2030, and will be considered extremely wet by the year 2100." A lack of water that severe would make growth here pretty much impossible.