Moaning can be any number of things and can be completely normal. But it could also be a precursor to a collapse. It also may not make any noise at all until it's ready to give out. Tough to say without actually taking a look.
My response here is a bit late, but if we get another deluge and if the pitch on your roof is fairly shallow (less than 8" of rise per 12" horizontally... aka 8 pitch or 8-12 pitch or about 34 degree angle), you might consider clearing the roof with a roof rake (hopefully you can reach it!) or even shoveling it (but be VERY careful and, ideally, wear a harness... lots of injuries and deaths are caused by falling off of snow-covered roofs!). Try not to damage the shingles; they're more brittle in the cold and the adhesive is less effective.
Look in your top floor or attic for any sagging or cracking in the ceiling if it has sheetrock or similar, or if the rafters/joists are visible, again, look for sagging (cracking rafters/joists would be very bad and require immediate attention). If you're not sure, find a home inspector or even a friend of a friend with some civil/mechanical engineering or home-building background to take a look around. The roof isn't the only place you need to be concerned about damage... exterior walls are another problem area. Particularly under the sloped sides of the roof. Especially if there's any rot or termite damage. These walls hold up the roof. (Interior bearing walls do too, and while you shouldn't ignore them, they are more protected and less likely to be a problem.)
I've been raking my barn roof clear of snow (about a 5-12 pitch) because I'm not certain how much it can take. The rafters look great, but I know there's rot in the bearing walls. It has held up so far.