TOKYO, Nov 22 Japan's Nikkei stock average jumped 1.6 percent to a 6-1/2-month closing high on Thursday, boosted by gains in automakers and electronics companies on expectations that a sharply weaker yen will boost their earnings. The Nikkei ended 144.28 points higher at 9,366.8. It advanced 3.8 percent this week, its second-straight week of gains. The broader Topix climbed 1.2 percent to 776.43 to a four-month closing high. Japanese financial markets are closed on Friday for a public holiday.