I don't know. I do know that jet stream equals stronger steering currents. Plus, someone correct me if I'm wrong, but the jet stream is upper level, which means that you won't always notice a difference in your weather. I teach the basic facts about these things in my earth science class, but not often enough to feel 100% confident about it. Actually, now that I think about it, it's not the jet stream that causes the temp/precip changes, but the position of it determines how far south the fronts can come in from Canada. Now I'm going to have to pull out my old textbooks and look that up.

The thinking by the local mets is that it will hit that trough and get "picked up" by it, thus causing the N to NE turn the NHC is predicting. They are already basing their forecast on this, I think the problem is in the timing. I really don't believe they anticipated Ivan staying on the drifting westerly track as long as it did/has.