I have not found a better site than Mountain Weather Forecasts for planning my trips over the past 1.5 years. This site is the only site that I feel is accurate within acceptable levels. If they start charging for their accuracy, I would pay since they're that good. Another site related to them is Snow Forecast dot Com, although I don't use that one myself I have friends who do.
Check out the webcams on some Alberta highways to help plan your next trip to the hills.
Blue Heaven Cam (Click for webcam Site)