I would be very careful about going up there if there is heavy wet snow on the roof. Wet snow plus a day of drizzle will put a load of weight up there and adding yourself to shovel it off may be too much.
I know that when I had my AC replaced there were two BIG guys (pushing 300 EACH) up there working on it. I figure all that weight on a space the size of four boots means that roof construction is pretty darn strong.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW