I definitely know where you are coming from, Harvey, because I have been pummeling Mike (who has more familiarity with the phenom than any of my other friends) with questions, trying to build a "perameter" in my head. Unfortunately, every time I seem to set up an "if-then", Mike throws in yet another variation to the rule.
Example: Small-size trees that become fully buried during a huge one-time snowfall (like this last week) Many of the cross-country areas that Mike and Billy(bill-e-g) frequent now have a nice, clear meadowy look about them, but these buried 5-7' trees can become unpleasant tree-well landmines.