An upcoming television ad for Arrid deodorant features an attractive brunette watching clouds float from her bathroom medicine cabinet, an excercise that may earn her $10,000 this year. Which isn't bad for a 19-year-old graduate of Gaitherburg High School who a year ago left for New York to make it big as a model and . . . did.

She is Julie Gordon, whose all-American good looks won her the 1976 Miss Maryland Teenager title as well as a contract with New York's Ford talent agency.

You may have seen her in magazines advertising Clairol products, or wearing a pink "I'm Baby Soft" tee-shirt for Love's Baby Soft Body Mist. On television she's one of the Prell women who announces, "I was flat until I was fluffy" while pointing at her hair. She's done somersaults for Toni and worn a little red Gino's hat to greet a man walking out of an ocean with the line, "Oh, you'd like Gino's new, crispy fish!"

Quick success (she was chosen for a national magazine ad her first day hunting assignments) buys her a $450-a-month apartment across from Lincoln Center and she will spend part of this year modeling in Paris.

Gordon, who hopes for a movie career, finds some of her commercials "really dumb, really ridiculous" and doesn't mind admitting it's no picnic repeating (as she did in the Arrid commerical), "Clouds, Mom! What are clouds doing in here?" sixty-five times for finicky producers. Especially when there aren't any clouds coming out of the cabinet - they'll be drawn in later by artists.

"But," says Julie Gordon, "it sells."