I have some knowledge of Washington State and the levels of turbulence One can encounter there particularly in the Mountains.
One particular flight during a Frontal Passage which took me east of Seattle in the vicinity of the Snoqualamie Pass where the Interstate Highway crosses the Cascade Mountains....was a genuine experience.
Fortunately I was in a Hughes 500E....and it made for a very uncomfortable ride....one I did not wish to take but did so as a teaching point to my Corporate Passengers. I had told them it would be very rough but within the capabilities of the aircraft and mine as a Pilot but I felt it would not be advisable to go. That was a "No!" but as they had gotten into the old game of trying to argue about such a decision I felt it was time for a lesson on why Pilots sometimes utter that horrible word to them.
They insisted they just had to go by air notwithstanding my explanation for why that was not a wise thing to do....and we set out to cross the mountains.
We did not succeed and only after they realized I in fact knew what I was talking about....agreed to land at a Truck Stop and have their meeting at that location instead of the Saw Mill to which we were headed.
They never challenged a "NO!" after that.
A Robbie would never have survived that level of Turbulence.
Every aircraft has its limitation as does the Pilot flying it.
I would not have considered doing that same flight in a Jet Ranger either....and probably not even a Huey.
I have a lot more faith in Articulated or Rigid Rotor type Rotor Systems than I do the Two bladed Mast type systems used by Robinson and Bell when it comes to Turbulence. It is one thing to hear Droop Stops pounding in flight as compared to Mast Bumping.