Aspen

You can trigger a widely propagating avalanche on weak layers buried in the snowpack. The most dangerous slopes will be those where new or wind-drifted snow contributes to the overloading of these layers. Cracking and collapsing may warn you that you have found dangerous snow at the surface, but the deadly monster lurking deeper in the snowpack will give you no warning. On slopes with a weak layer, seek out slopes less than 30 degrees for safer riding. 

Pay attention to precipitation type at elevations close to and below 9000 feet. If it starts to rain, avoid being on or under steep slopes.