Despite the fact that Denver gets over 53 inches of snow every year, there is almost never any snow on the ground during the course of the series.
From season 3 to season 6, Alexis lived in a lavish three floored penthouse apartment. The apartment was on the top floor, as seen in the external establishing shots in which you would see the terrace/balcony which was accessed from the lounge. However, the building did not have a floor higher than this, and so her bedroom could not possibly be up a flight of stairs as seen in the studio set.