Odds are that this winter’s going to be a wet one. The intermittent climate phenomenon known as El Niño, which typically means more rain and snow for California, developed over the summer and is expected to intensify in the next few months. And this year’s El Niño is predicted to be an exceptionally strong one — maybe even ranking in the top five on record, according to Daniel Swain, a climate scientist at U.C.L.A.