Jazz vocalist Susannah McCorkle was rushing helter-skelter in the couple of hours between arriving at Union Station and show time at Charlie's last Monday. Later, on the way to the club for the evening's show, she found herself minus her music. A hasty return to the carryout, now dark, where she earlier had grabbed a sandwich to go, roused the proprieter, who handed the frantic singer her scores. All in a day's work for McCorkle, who commutes from New York for her once-a-week gig at the Georgetown club, sings at Greene Street and The Cookery in New York, and has an album out on the Inner City label.

Although born and bred in California, McCorkle found jazz when she went to Paris as a translator in French, German, Spanish and Italian. While residing there and in London for five years in the early '70s, she appeared in concert with Dexter Gordon and Ben Webster, toured with Bobby Hackett, and sang with leading English jazz musicians. A self-confessed admirer of the older forms of the idiom, she numbers Billie Holiday, Bessie Smith, Lester Young, and Stan Getz among her chief influences.

Of her month of Mondays at Charlie's she says, "It's like singing at a party where someone says, 'Why don't you sing a couple of sings.'" But it's also like going back to that earlier time from which McCorkle draws her materials. "In the old days, the clubs used to get behind a young performer that they liked and build that young performer's name. Charlie's likes me, and they think I can have a following there."

She'll perform there again tomorrow night and May 4 with pianist Keith Ingam and bassist Steve Novosel.