You mean the only place under 500'? Or are you just counting 6"+ as a good snow event?
I believe the Olympia area and other parts of South Sound and Hood Canal did decent with snowfall for the winter, though of course none of it stuck around long. Bunch of days in December with highs in the mid 30s and plenty of precip.
Then late Jan 2008 was a classic near miss with continental cold and a ULL that dove just a bit too far offshore. Believe OLM also scored some snow with that, though.
I believe Bellingham area also scored some snow in late March 2008, late January, and a little in December as well with some very chilly days.
But yeah...just a few tweaks and nudges in the pattern and that winter could have been so much better in the lowlands.
That was such an odd winter. Seattle had all of these minor events where it snowed lightly for hours without amounting to much. The strangest one was on March 28. It snowed all afternoon but the grass barely got a trace.