Chiming in with Jim, I've learned that bumps are there or not there at the whim of the Almighty, it seems. For instance, last weekend I flew from Greeley (where I keep my airplane) to Durango to visit my Sis, via Pueblo, GOSIP intersection, over LaVeta Pass, Alamosa, BRAZO intersection, Durango, on Friday. Because it was pretty warm, I used flight following instead of my usual practice of filing IFR, because I was pretty sure I couldn't get my Little Red Bird to the 14,000' MEA necessary for IFR flight--and I was right.
So on the way there, I was at 10,500' until just south of Colorado Springs, then climbed to 12,500' for the remainder of the trip. On the way home on Monday, with the temp 92F at Durango, it took a long time to climb to 11,500'. I followed the same route, in reverse. To get over the ridge to the San Luis Valley, I got it up to 12,500' for a short time, then descended again to 11,500' across the Valley (hemispheric rule, you know), then up to 12,500' to go over LaVeta Pass, then back to 11,500' until the turn at Pueblo which put me on a slight westerly heading, where I climbed to 12,500' again for the remainder of the trip.
On the way down, I had about 8 minutes of smooth, and the entire rest of the trip down, 3.7 more hours, was bumpy. Not horrible, just constant bumps. Ol' Molly dog wasn't too happy about it, and neither of us banged into the ceiling, but it was pretty constant. On the trip home, however, it was just about the opposite, about 8 minutes of bumps around Colorado Springs, and the rest of the trip, about 3.1 hours, was as smooth as a billiard table.
The relevancy of all this is that the weather both directions was almost exactly the same: similar altimeter settings, similar winds, similar temperatures (actually a bit warmer at both ends on Monday compared to Friday, but not much). Why was the trip down mostly bumpy, and the trip home mostly smooth? I haven't the slightest idea!
Cary