Atmospheric conditions that helped create the recent multiyear California drought have returned, leaving the state dry and exceptionally warm this winter and its residents wondering if another long dry spell is on the way.

A ridge of high-pressure air off the West Coast has persisted for much of the past three months, blocking many Pacific storms from reaching California and weakening others that do get through. Normally such ridges tend to come and go, but they also lingered during the 2012-16 drought, the worst in the state’s history.

“We are now seeing another year that looks like one of those drought years,” said Daniel Swain, a postdoctoral researcher at the Institute of the Environment and Sustainability at the University of California, Los Angeles, who during the drought coined the term “ridiculously resilient ridge” to describe the atmospheric pattern.

“This one is definitely a resilient ridge, but we don’t know if it’s quite reaching the ‘ridiculous’…

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