California radar storm estimate, evening 3/14/2012

As I write this, California’s being pounded by a particularly impressive storm.

According to Mike Dettinger, it’s an “atmospheric river” storm, one of the type he and other climate/water researchers have been studying increasingly closely because of their importance to California’s water supply. As I wrote last year, California has the most highly variable precipitation in the country (as measured with the standard deviation divided by the mean), with annual water supply strongly influence by the presence or absence of a handful of these AR storms. From a paper last year by Dettinger et al:

If just a couple of storms do not arrive in California, or yield significantly less precipitation than needed, in a given year, that year’s precipitation total and water resources suffer disproportionately, compared to other regions. Alternatively a relatively few large or “extra” storms may result in a particularly wet year.

This year, we seem to be having a year that was extremely dry getting a last-minute reprieve by an AR blast.