Raymond Leppard was guest conductor with the National Symphony last night at Wolf Trap, with violinist Eugene Fodor as his soloist. There may be something in Fodor's playing that attracts thunderstorms. His last appearance at Wolf Trap, which was the Philadelphia Orchestra, was accompanied by a violent display of lightning, thunder and rain.

Last night the lightning appeared in the distance just as Fodor was moving through the finale of the Mendelssohn, to which he added his own brand of technical display. The first drops of rain did not appear until after intermission, when Leppard was conducting the Sibelus' First Symphony. It came as no surprise to any one who have heard Leppard's direction of Benjamin Britten's "Billy Budd" with the Metropolitan Opera that the English conductor is a thorough master of the largest forces in music. His Sibelius was well paced but always graced by an expansive fuidity in phrasing that made its yearning pages highly expressive.

For the Mendelssohn Concerto, Leppard reduced the orchestra to chamber proportions, using 44 players to achieve a result of welcome clarity and lightness. Fodor's tone can be a lovely thing, though at times he drives it a bit hard, raising problems in intonation. He played with more spirit than elegance.

The evening opened with a powerful and often exciting account of the Capriccio Espangnole by Rimsky-Korsakov. The orchestra took the famous challenges well in stride, with gorgeous solos from Loren Kitt's clarinet and Toshiko Kohno's flute and a great splash of sound from Dotain Carter's harp. Leppard rode even the wildest passages with the iron control of a master charioteer.