For years now, Bob Nicks, president of the Austin Firefighters Association, has been the city’s very own Cassandra, the Greek mythological figure whose prescient warnings go unheeded as doom approaches. Like those of his fabled counterpart, Nicks’ warnings are also about the fiery destruction of a great city; in this case, Austin, which Nicks and other experts believe is increasingly vulnerable to devastating wildfire. When I last spoke to Nicks, in January, he outlined a distressing wildfire scenario for Austin, but one that hinged on a seemingly remote possibility—the idea that the blaze would be sustained by 35-mile-per-hour wind gusts from a tropical storm that perched itself northwest of the city for a day or two. But Nicks recently saw evidence that a tropical storm might…