Never jump out of the boat in front of a log jam- if you think your boat is going to get caught in it or sucked down and you know you gotta bail I would suggest trying to climb on it. The water psi
when it hits a jam especially at high flows is absolutly incredible and the water has to get around it some how so it funnels down and acts like a massive vaccum. I had a very bad inccedent on the cle elum river about six years ago when me and a frieng got sucked into a huge log jam and barely made it out alive. I can not empisize enough on beaching your boat and walking down and looking to see which way you have to set up to make it through safely. Often people make the mistake of not doing this and it has cost them their boat, gear and sometime their lives!
You never know what lies around the next bend after a high water has gully washed threw.
BE SAFE!