The Ridiculously Resilient Ridge: direct cause of California's drought

Last edited Sun Apr 19, 2015, 03:13 PM - Edit history (1)

The "Ridiculously Resilient Ridge," sometimes shortened to "Triple R" or "RRR," is the nickname given to a persistent region of atmospheric high pressure that occurred over the far northeastern Pacific Ocean during 2013-2014.

This anomalous atmospheric feature disrupted the North Pacific storm track during the winters of 2012-2013, 2013-2014 and 2014-2015, resulting in extremely dry and warm conditions in California and along much of the West Coast.

The Ridge comprises the western half of atmospheric ridge-trough sequence associated with the highly amplified "North American dipole" pattern, which brought persistent anomalous cold and precipitation to the eastern half of North America during 2014 in addition to record-breaking warmth and drought conditions in California.

The Ridiculously Resilient Ridge is characterized by broad region of positive geopotential height anomalies on monthly to annual timescales. This persistent ridging acts to "block" the prevailing mid-latitude Westerlies, shifting the storm track northward and suppressing extratropical cyclone (winter storm) activity along the West Coast of the United States. Such a pattern is similar to—but of greater magnitude and longevity than—atmospheric configurations noted during previous California droughts.

The "Ridiculously Resilient Ridge" nickname was coined in December 2013 by Daniel Swain on the California Weather Blog.

http://en.wikipedia.org/wiki/Ridiculously_Resilient_Ridge

In an article published by the San Francisco Chronicle on April 19th, 2015, Daniel Swain is quoted:

"There probably isn’t a single answer to why the Triple R is here, but we keep looking into it. It’s pretty weird. The Triple R is arguably an accurate description of a fairly complex geophysical phenomenon. It is a ridge. It’s not permanent, it’s resilient. And then of course, it is anomalous and not something you’d expect to see — so it’s ridiculous."

Earth Scientist Noah Diffenbaugh, of Stanford University, suggests the increase of global temperature is helping to fuel this resilience.

Diffenbaugh continues: "We are in a different climate than we were when our current infrastructure for water was built, says Diffenbaugh. "And decisions on how to handle our water need to be made on the current climate, not the old climate.”

LINK (requires S.F. Chronicle premium digital and print coverage subscription to view -- you could also just buy a Sunday paper): http://www.sfchronicle.com/science/article/New-normal-Scientists-predict-less-rain-from-6209104.php?cmpid=gsa-sfgate-result.