I've been wondering how 11/19/2000 works out as an analog to this. I need to look into it.
https://www.wunderground.com/history/airport/KCLT/2000/11/19/DailyHistory.html?req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=
The sounding for the RDU airport at 84 is concerning because it isnt necessarily above freezing, you dont reach -15C until you get above the 500MB layer. It's hard to grow snowflakes like that.