January 1991 is the one I remember from the early 90s I think. We hadn't had a 6+ event in a long time and everyone was excited that we'd get a 6 inch snowstorm even though it would change to rain later. It snowed most of the day and didn't change to rain until after it was dark, which was perfect timing, the reverse (snow at night rain during the day) would not be as nice. Of course the following month, February 1991 I think it was, we had the 36 hour 9 inch snowstorm, so we ended the 6 inch snowless streak with a bang (and a busted forecast, as no snow was predicted, it was just supposed to be a frontal passage- and neither BOS nor PHL got snow like we did.)
On the topic of snow to rain, wasn't January 87 another heavy snow to rain storm? Maybe just at the end?