I'll list events that busted in our favor. Some were major. Sorry if some have been mentioned already.
1/23/87: This was the first of 2 big storms to hit out region. Most forecast we're for 2-4/3-6 with the possibility of changing to rain. Instead a lot of areas saw a foot or more with temps falling through the 20's
2/20/79: Blizzard of 79. Most forecast were for a decent size storm but not for 20 inches.
2/12/83: Blizzard of 83. Same as above. Amounts over 2ft.
12/8/13: Already mentioned by Fozz
1/9/96: This was 2 days after the blizzard. A disturbance/clipper produced 3-6. Forecast was for a few flurries with some areas getting a dusting.
1/4/2002: A clipper overproduced and some got up 5-6 inches. Forecast was for C-2.
Late December 1990. I think it was the 28th or 29th. Forecast was for some snow but this storm over produced. 4-8 inches in a 4-6 hour period.
12/7/2007: A clipper gave some areas up to 6 inches.
1/25/2000: already mentioned
1/30/2000: northern suburbs got 4-8 when forecast was for 1-3 then mix.
2/12/2006: an awesome deform band produced amounts up to 16-20 inches in areas like Columbia, Randallstown, Reisterstown etc. No forecast called for more than 10-12. Most forecast were for 5-10.
12/25/2002: northern suburbs got 5-7. Not well forecasted.
Here are some more without details
3/9/99
2/25/2007 to some extent
1/10/99 to some extent
11/11/87
Probably forgetting a few more.