Patterson Mountain is an established hike, with quite a few resources providing the details. WA7JNJ's previous trip report should provide plenty of information for fair weather activations, so I'll focus here on my experience doing this hike in January.
My wife and I snowshoed this trail just a week and a half after an unusally strong winter storm dumped between 1 and 4 feet of snow on the eastern slopes of the Cascades, closing all of the passes that cross the Cascades in Washington for several days. The temperature at the trailhead was just below freezing, and we found roughly 2 feet of snow on the ground. The trailhead was plowed and I had no problem getting in or out with my AWD crossover. There were some icy patches on the road but nothing that posed any real obstacle.
Someone had already broken trail to the summit, which saved us quite a lot of effort and also made navigation easy.
Last time I was here, I went to the summit marked in the SOTA database. This time, I double-checked that the north summit (with the cistern) was within the activation zone and set up there instead, saving some hiking.
