I think I may have seen only 5 big snowstorms (10"+) in the past 50 years in a Nina. A couple of them probably didn't reach that criteria in the metro areas, like Jan 1971 and Dec 1973 ? Other than that, its just Jan 1996, Jan 2000 and Feb 2006 as best I can recall.
The models at various times in the past week have offered up 3 different storms that size. I will remain skeptical until I see a similar solution under 72 hours.