Following an old track does not necessarily mean a slope is safe. Down-slanting trees and brush indicates previous avalanche launches. Sun crust on old snow can cause new snow to slide off. Rough surfaces generally favor stability of new snow cover. Loose underlying snow layers are more dangerous than compacted ones.
Recent avalanches indicate dangerous conditions.
Snow falling at the rate of an inch or more per hour increases avalanche danger. Snow crystals in the shape of needles and pellets result in more unstable snow conditions than the typical star-shaped snowflakes. Snow saturated with water can avalanche, especially on south facing slopes and beneath exposed rock. Rapid changes in wind, temperature and snowfall cause changes in the snowpack and may affect stability. If the snow cracks and the crack runs as you step, the danger of slab avalanche, the most serious type of winter hazard, is high.