The Rev Tent's "4 -season" refers to the full top to bottom fly sheet.  This allows you to crack windows of the inner tent for ventilation (to reduce condensation) while the outer fly keeps the rain or snow out.  The Rev Tent is sloped to facilitate water run off, but it is possible that sticky snow may gather on top. This isn't a problem as the poles are strong and there is about 6" of space between the inner tent and outer fly at the top.  You can always reach out of the inner tent and push snow off the outer tent from underneath if it gathers, all without getting off your butt.