ROUND 2! ( kidding ) - Anyways, probably not a bad idea getting at least 4 hours of sleep tonight!
Daniel, one thought on the dry slot that you mentioned. I think it may be just that - a dry slot, but beyond that, in looking at the 0Z GFS data, and checking all levels from 200mb down to surface, I was able to find a minimal reflection of this feature between 500mb and 700mb. There was however, minimal wind shift noticable at any level with this feature, and furthermore, was not in phase with the stronger short wave over ( or just west of the Great Lakes ). That is to say, that it was not "attached" to any feature out of the westerlies, and underneigth the more or less zonal flow. Just not sure how this feature itself serves as any mechanism for steering.

And.................yawn.......good night..... zzzzzzzzzzzzzzzzzzzzzz