White supremacists from Stormfront, an online forum with more than 330,000 members, traveled here this weekend for a conference replacing what had been billed earlier as their annual Great Smoky Mountains Summit. Don Black of West Palm Beach, Fla., a former Ku Klux Klan grand wizard and the forum's founder, announced the Sept. 30 weekend event in July. In the time since the forum's domain hosts removed the site from the Internet, Black became ill and withdrew from its planning, according to Billy Roper, another prominent white supremacist who took over the conference. Saturday also is Yom Kippur, the Jewish Day of Atonement and the holiest on the religion's calendar. Roper, whose ideology is neo-Nazi according to the Southern Poverty Law Center, said the date of the conference was a coincidence.