Here’s a challenge: how do we describe a hula performance on the radio? Well, by establishing a strong beat, for starters. Now imagine how the Te Pura O Te dance troupe of South San Francisco might be moving to this. They’re just one of scores of performers appearing this weekend, August 3-4th at the 18th Annual San Francisco Bay Area Aloha Festival. This free event takes place at the San Mateo County Event Center, in San Mateo.