THE DAILY NEWS OF LOS ANGELES DATE: MONDAY March 29, 1993 EDITION: Valley SECTION: L.A. LIFE ZONE: rop PAGE: L21 LENGTH: SHORT JELLYFISH TO PERFORM IN VALENCIA The last time Jellyfish vocalist Andy Sturmer visited Six Flags Magic Mountain, he got soaked on Roaring Rapids and had to go home early. This time he plans to stay off the rides until he has finished performing. In an event sponsored by new-rock KROQ-FM (106.7), Jellyfish will appear at the Valencia theme park on Saturday for two free concerts (with park admission). The concerts are part of the theme park's Spring Concert Series. ''I've always wanted to play there,'' Sturmer said. ''It's such a fun place to be. The last time I was there, I got completely drenched. I plan to make up for it this time.'' The eclectic alternative-rock band is touring in support of its new ''Spilt Milk'' album. While at Magic Mountain next month, Sturmer said, he plans on riding Psyclone and Flashback, ''but my favorite coaster is Revolution.''