Where oh where was Willard Scott yesterday? Surely he would have twiddled the right dials on his weather machine to blow the storm clouds out of town Sunday morning so that the sun could have dried off the Capitol's west lawn. After all, this was the scheduled site of the National Symphony's final summer season performance. More important, this concert was to mark the departure of associate conductor Hugh Wolff, who after six years with the NSO will take over as music director of the New Jersey Symphony.

In Scott's absence, Plan B went into effect. The Kennedy Center Concert Hall was available, dry and already equipped with rest stations. Better still, the musicians and audience wouldn't have to endure the humidity and insects.

As it turned out, these "makeshift" quarters proved quite satisfactory indeed. The NSO played splendidly, giving Wolff the upbeat send-off he justly deserves.

The evening was a casual event, as the shirt-sleeves-and-shorts crowd (black socks, optional) took advantage of the festival seating arrangement. The program was a collection of sonic marvels, which the players presented in an aggressive fashion. Berlioz's Overture to "Benvenuto Cellini" received an especially vivid reading, with the brass and woodwinds taking top honors. Wolff and orchestra then promptly showed how potent a blend of color and dynamic control can be in Stravinsky's "Firebird" Suite.

Music of America balanced the bill in true pops fashion. A medley of tantalizing George Gershwin and Cole Porter songs set feet tapping, as if anticipating Aaron Copland's "Hoedown," the last of four excerpts from "Rodeo." And what better way to finish things off than to call upon a Washington native, John Philip Sousa. A breath of brisk march air came under the headings "The Washington Post" and "Stars and Stripes Forever." Wolff stopped conducting briefly in the latter, giving a sly "look Ma, no hands" look over his shoulder during the piccolo solos. He laughed last and best, for the encore was also "Stars and Stripes."

Trite as it may sound, the obvious point made last night is that the NSO's loss is New Jersey's gain. But then the Garden State is just up the street. And Wolff figures to be a most welcome guest conductor here for many years to come.