In terms of ski area snowfall there is no climate trend in my ski area snowfall data. The data starts in the 1970's and nearly everyone agrees that temperatures warmed in the 1980's and 1990's and have generally maintained a plateau since then at a higher level than the 1970's. As noted in the original post the 4 worst seasons were all before 1993 and the best season was 2010-11 (with 2007-08 being among the next 3 best), so there is no case that snowfall in North American ski areas is in decline. If you're concerned about temperatures look to altitude, as the lowest altitude places get occasional rain now and more of the precipitation might flip from snow to rain if temperatures resume rising. So regions like Colorado and Alberta that get essentially zero winter rain look safest to me if warming is your concern. Or choose the highest altitude places in other regions (Alta/Snowbird/Mammoth/Bachelor/Big Sky/Targhee).
It's also true that every 300 miles or so of change in northern latitude roughly equals 1000' feet of change in vertical. The safest bets, assuming that temperatures increase over time, is a combination of altitude and latitude. So northern areas should fare better, at least the higher elevation resorts.
However, if climate is changing, then precipitation might not follow the historical patterns, either. A higher elevation/northern latitude ski resort that is located in a perpetual rain-drought region is no better off that a lower elevation resort with lots of rain. The damn thing is, we just don't know.
My sense (semi-educted guess, wild-ass guess) is that historical data, such as what Tony has presented (thank you Tony!) will be valid for most of our lifetimes, but maybe not the next generation's.