There is a a major misconception about parkas. Except for very extreme conditions the usual cold weather dress should be; wicking longjohns, one or more insulating layers and finally a wind anorak or similar shell and wind pants. A heavily insulated parka should be used for periods of relative inactivity around camp. the layered system makes you 'comfortably cold' while active and the parka 'comfortably warm' while inactive.