Probably 3/9/98. After what had been a subpar winter, this storm was a late bloomer, with no expectations at all until about 12 hours before the storm. 12-15 inches with 30-40 mph winds, followed by a couple of days of intermittent lake effect squalls.
Honorable mention would probably be severe weather on 3/2/12 & 5/30/04, and the heat and humidity of 7/14/95.