I compiled a list of snowstorms that were probably underestimated. Beginning with January 1996 and working our way backwards to include February 1978, December 1947, February 1920, February 1899 and March 1888.
Also keep in mind many of our borderline events that switched back and forth between precipitation types were also likely not measured properly because of this behavior of only measuring when an event ended, with lots of melting occurring before that happened.