You could see the signs, building in the subtle but unmistakable way that a low-pressure system gathers and roils before bringing the end of a drought — in this case, 62 years without Olympic gold in the four-man bobsled. It ended Saturday, in spectacular fashion, to the clanging of cowbells omnipresent at such races, as Steven Holcomb drove team Night Train — as USA 1 is known — to the gold medal.