On Sun, 24 Jan 2016 11:19:06 -0800 (PST), wrote:

My brother has 20" of snow on a 5/12 roof in Maryland, and rain has been forecasted for Tuesday.

I'm in Maryland, NW of Baltimore.

We had 30" of snow last night, but looking at my n'bors' townhouses,
they have only about 5" of snow on them. Maybe too much hot air in
the attic? Some of the snow is falling off the trees too.

The pictch is about 7-8/20 which is 4.2 to 4.8 over 12. I guess there
are no roofs that are 4.2/12, so maybe it's 4 or 5. Not much
different from your brother's.

Is the greatest danger from snow weight or from ice damming?\

Is he susceptible to ice dams?

He could go in the attic and maybe get an idea. Is any part of the
roof sagging?

What would be the best strategy for the next 24 hours?

I havent' done this but maybe hit the roof pretty hard with a baseball
bat and get some of the snow to slide off.

Worry about the north side of the house. I realize I'm looking at the
south side, or east and west sides, of my n'bors. I can't see any
north sides but I know they get less sun and melt slower.

Thank you very much in advance.

Jutta Gibb