The “Ridiculously Resilient Ridge” is Frickin' Resilient

Despite the nearly-normal rainfall in northern California this winter, there is no indication yet that the recent pattern of drought in California is going away. The Pacific Decadal Oscillation (PDO) has been strengthening again this year, which just means continuing trouble:

Over the past several years, California weather watchers have become well acquainted with the now-infamous “Ridiculously Resilient Ridge” of atmospheric high pressure—the unusually persistent atmospheric anomaly responsible for redirecting winter storms over the Pacific and ultimately bringing record-breaking warmth and dryness to the Golden State. Like a boulder displacing a narrow stream of water, this sluggish atmospheric feature consistently deflected the storm track to the north of California during the typical “rainy season” months of October to May. As a result, much of the state was left high and dry—even during what is typically the wettest time of year.