cncpc,
I was wondering the same thing and did some searching. Here is the Calgary International weather for the 2100 Local departure time (0300Z):
METAR CYYC 290300Z 09004KT 9SM -RA BKN027 OVC039 14/11 A3028 RMK SC5SC3 PCPN VRY LGT SLP270 DENSITY ALT 3900FT=
Light winds, nine miles visibility in light rain, broken clouds at 2700’ AGL (6200’ ASL), overcast at 3900’ AGL (7400’ ASL), 3º dew point spread.
Near the accident site, the valley floor elevation is about 4300’ and the ridge tops are from 6200’ to 7200’. So not a good evening to be flying VFR in the mountains.
I couldn't find the winds aloft report, but I live southwest of Calgary with a good view of the mountains and I didn't see any lenticular clouds that evening, so I expect the winds were fairly light.
https://www.ogimet.com/display_metar...f=59&send=send