yes this is true because the snow takes longer to settle and pack. this creates layers as temperatures vary for different snowfalls, making certain layers more slide prone, the lighter snow doesn't hold as well, making those layers more likely to give. but this is relative, as colorado doesn't recieve as much snow as other places, while other places like utah and the PNW, have much more snow build up, putting more weight on lower layers making them very prone to avalanches. also, steepness has to do with avalance danger, though after a certain point, the danger sarts to dimishes as very steep areas donot hld snow as well making the snow that actually stays relatively more stable (as in a 60 degree slope vs. a 45 or 50.) again all is determine by the layers of snowpack, this is why you dig a pit to determine danger before you drop in, in the BC.