This is a bad time to run into bears. Like bmccasland said, the adolescents are out on their own for the first time and they're ALL hungry. So they're a bit twitchier than usual. In general, though, the black bears aren't a problem. I've done a solo backpacking trip in King's Canyon Nat'l Park, where I've ended up with bears in my camping area. After I yelled and threw a few rocks at them, they moved off (slowly, but they did leave).

They will peel open a car if they smell food. Yosemite is notorious for that. Put everything in a bear box if you can.

The bear this morning was much bigger than an adolescent. It's probably the same bear I've seen over the past couple of years around here. This was the closest I've ever seen it to my house.