This episode's headline: Deep Freeze; Unplugged!; The Forbes Factor; Political Wrap; In Memoriam. ANCHOR: JIM LEHRER; GUESTS: FREDERICK OSTBY, National Weather Service; KEN AULETTA, The New Yorker; RICHARD MacDONALD, Media and Telecommunications Consultant; PAUL GIGOT, Wall Street Journal; MARK SHIELDS, Syndicated Columnist; CORRESPONDENTS: JEFFREY KAYE; ELIZABETH FARNSWORTH; MARGARET WARNER;