Brown saucer-shaped object with dome on top flying beneath low cloud coverObserved while traveling west on Interstate 80, west of Rawlins, WY. Craft was brown, saucer-shaped with dome on top. Craft was hovering high above the ground, beneath low rainclouds. Craft then very rapidly shot almost straight up, like a backwards letter 'J', into the clouds, and disappeared. Terrain was hilly. Weather was wet, cloudy. Observer is a twelve-year old boy traveling with family on vacation.