The best winter scenery I've ever seen was by Rand Hood in Model Railroader a few years ago. He models D & RGW in the Rockies and if memory serves, it was a two part article. I think it was done in the 1990's but I can't remember any closer than that. If you "google" Kalmbach Publishing-Model Railroader", you'll get to their web site. They have a listing of back issues from the 1970's on, and each time you click on an issue you get a synopsis of the main features in the magazine. The back issues are $5.50, older issues may be less. It may be a bit tedious looking through them all, but the articles are well worth it for someone wanting to model a realistic winter scene. Another Gauge member may be able to post the issues I'm referring to.
I just spent some time looking at the Model Railroader wed page, and Jan 1996 has an article "How To Model Winter." It isn't mentioned in the blurb on the contents of Feb. 1996, but if memory serves it was a 2 part article so you would need both issues. I did a second search and found another article titled Modeling a Winter Scene Jan 1980