Sun angle still melts the snow with alarming speed even in late December if the sun is out right after a snow event. Definitely not challenging you - so hope you're not taking it that way. My point is, the only tried and true way to get "long lasting" snow cover is either to get a huge quantity of snow, or some sort of "cap" on the snow cover like a sleet or ice layer. I've even seen snow melt during the day with temps at like 25 or below if the sun is out.
Give me January, big snow storm, no big warm up right after and a sleety storm to top it off.
1-3" will be gone quick unless you time a vodka cold airmass right after it.