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.