This spring, veteran Washington weathercaster Bob Ryan moved from Channel 4 (WRC-TV) to Channel 7 (WJLA-TV). The move might have seemed like a bombshell to D.C. viewers: after all, Ryan had been at WRC for a full three decades. But his arrival in D.C. back in 1980 was a major event of its own, with implications for both local and national weathercasting. Ryan came onto the Washington scene as part of an unusual job switch with none other than Willard Scott, who was a fixture in the D.C. media world before gaining national fame on NBC’s “Today” show. I’ve blogged about the Scott-Ryan switcheroo here, at the Washington Post’s Capital Weather Gang.