Meteostar has been incredibly accurate in the past but has been down for the last few days.
Anyone know another site that has an accurate 16-20 day model?
Those long term forecasts are a crapshoot. 48-72 hr is generally pretty accurate as far as snowfall totals these days and anyone else that claims longer is lying. I've seen NOAA drastically change snowfall predictions in the 12 hr time frame leading up to a storm. These guys make a best guess even with all the technology out there. 5-10 day they can tell you at best if there is a good chance of snow or no chance of snow. The site got lucky if they predicted 10+ days out. Opensnow.com is your best bet. You can get a premium membership and actually ask the forecasters to look at your ski area and give you solid info.
Actually forecast 24 hrs out are much more accurate that those that are long dated. Beyond 5-7 days out, there isn't much information in the forecast.
Joel Gratz has this