This is an analysis a guy on another site did, I thought it was good so maybe something to stimulate more conversation:
I think a lot of good points have been made here re chosen route. GPS direct from KBJC to KCNY is 226nm. The favored route in my mind from Jeffco west is the one stated here by others and that is Corona Ps (Rollins on the map) D Kremmling D KCNY. Looks a lot longer on the map....truth is at 231nm its only 5nm further to have much less exposure for a much briefer time than over that section of I-70. From what I can dig up on mtn top winds yesterday, Berthoud pass ~9nm NE was 300 degrees at about 15-20. Copper mtn ~15nm SW was 270 at 21G24, again fairly benign for a typical mtn summer day. What I think will prove to be one of the big factors was at about 8am the Copper Mtn AWOS temp at 12,400' was 55*F....thats hot! Best of my back of the napkin calculations gives a DA of about 15K. So we have the perfect storm in action...westerly winds blowing up two long canyons on the west side meeting 30 degree divergent air moving over high peaks to the N, coupled with normally aspirated plane trying to climb enroute with 15K DA, and judging by the crash site above chair 5 at the Valley section of Loveland basin I am going to surmise that following the highway presented them with a 13,000' ridge where they planned to cross over the tunnel. (that is NOT Loveland Pass) Realizing that they couldn't clear that ridge and likely staying on what would appear to be the safe side of the valley (N) turned out to be the upwind side of the valley so that the "downwind" turn that was made instantly gave them a nice tailwind boost into the terrain on the S side