This is my understanding of the situation. I'd appreciate any feedback by people smarter than me.
The variability of identifying the size, strength, orientation, and velocity of the northern stream short waves over the Pacific by satellite imagery has certainly seemed to have decreased. In other words, the medium-range models (with the exception of perhaps the CMC) have zeroed in on what they believe to be solid information for those shortwaves. Of course, there is an assumption that such information gleaned by satellite imagery equals reality. That's still a fairly big assumption. It's my assumption that information derived from airplanes and weather balloons leads to an approximation of the size, strength, orientation, and velocity of the short waves that is significantly closer to reality.
Notwithstanding the above, I suppose that we could still see a substantial (or insubstantial?) change in the speed, intensity or location of one of the northern stream that is the result of how poorly (or how well?) the medium range weather models emulate reality based upon their assumptions from satellite imagery and the "correction" comes from better information derived from airplanes and weather balloons. Because I'm so snow-obsessed, I'm strongly hoping for a northern stream shortwave that magically jumps northward so that our storm is not crushed to Cape Horn.
So the above explanation is the thread that I'm clinging to...