The fledgling Washington Jazz Association kicked off its opening session yesterday at the National Press Club with an all-star line-up, the likes of which are not often seen in these parts. w

Pianist Dave McKenna led off with a multi-form "Sweet and Lovely" that contained hints of stride and boogie amid its lilting melodic line and abrupt tempo changes.

The brittle edge and punched-out phrases of veteran tenorist Al Cohn were nicely contrasted with the supple fluidity of the youngster Scott Hamilton, also on tenor, on "Robin's Nest."

Equally effective in duo were trombonist Jimmy Knepper and baritone saxophonist Pepper Adams. "Stella by Starlight," ushered in by Knepper, was satin-smooth at first, but in the hands of Adams turned rough and raucous. Knepper's range and control are astounding, and Adams' predeliction are the apt musical quote evidence of a lightning-fast mind. Vocalist Carol Sloane declaimed a droll "Saga of Frazier the Aging Lion" with pianist Jimmy Rowles padding softly in the background. "Taking a Chance on Love" had her swirling the melody over the steady bass line of Steve Novosel and the crisp, authoritative drumming of Eddie Phyfe, producer of the concert.

When all four horns got together on "Sweet Georgia Brown," one realized that here was a group that could "Swing You into Bad Health."

Look for another session in March. Same place, different faces.