There have been two winters on record with ~2.0 RONI peak that were quite cold in the SE, 1957-8 and 1965-6. Also, 1972-3 and 1982-3 both had historic winter storms and they peaked way up at 2.2 to 2.5 per RONI.
I was born in March of 57 so I can't say much on that other than they were good years but I do remember the 72-73 winter pretty well in the upstate of SC as I had short sleeves to start out the day,not sure it was Dec or mid Jan but just got out of class at school and was pumping gas in my car, just 16 and not long had gotten my drivers license. Long story short an Artic cold came through town with such strong winds that traffic signals fell, trees blew over, I helped chase a mans toupee across the parking lot. In the time it took me to pump gas, pay for it get back in car and get home about 40 mins temps were below freezing and snow had began to fall. We probably talking a 40 degree temp drop in a short time. I never will forget that day.