Animation of total precipitable water in the atmosphere March 2-5, 2016. (Source: Space Science and Engineering Center, University of Wisconsin) As I'm writing this, rain and snow has finally arrived in California — and as the animation above shows, some of that moisture has traveled an exceedingly long distance. As in all the way across the Pacific Ocean. The animation shows the evolution of total precipitable water, or TPW, in the atmosphere for 72 hours between March 2 and 5. If you could convert all the water and water vapor contained in the atmosphere, from top to bottom, into the liquid phase, TPW is what you'd wind up with. The deepest reds in the animation above show TPW amounts in excess of 2.4 inches. This is the feedstock for storms, including the one now hitting California. Note that long tongue of moisture stretching all the way from the Philippines on the western side of the Pacific to the west coast of North America. Also check out a shorter tongue reaching from the Hawaiian Islands in the central Pacific. These are classic atmospheric rivers of moisture that tend to spray California during its wet season (except, of course, when it is experiencing a drought). They are even more common during El Niño events, like the one still going on. What you're looking at in the animation is what has been loaded up for California in the current storm, which is expected to last into Monday. Very heavy snowfall of up to 4 inches per hour is expected in the Sierra Nevada Range tonight (Saturday). By Monday, some areas could get up to two feet. And this is just the first round. Another blast of precipitation is forecast to hit next Thursday night into Friday. Here's the forecast for total precipitation over seven days, starting Sunday March 6 and ending on March 13:
The forecast for total precipitation between March 6 and 13, 2016. (Source: NOAA) Check out those 16 inches of water forecast for Northern California. That's impressive! So is the blob of heavy precip totals forecast for a region stretching from Texas and Oklahoma east across the lower Mississippi Valley, and up to Missouri and Illinois. These two things are not unrelated. El Niño forms a link between them. For more information, check out this detailed post at Weather Underground. If it really does pan out this way, California will get a nice boost to its snowpack, and a desperately needed dose of drought relief. But at this late time in the wet season, it would take a veritable meteorological miracle to bail the state out of what has been estimated to be the worst drought in 1,200 years. We can, however, hope for some significant measure of relief.