Ok, I ran some numbers for DCA. For the period 1950-forward, the correlation between temps and snow gets stronger as you go through the winter. We root for cold and hope for precip. Snow on the vertical axis, temp departure from current norms on the horizontal axis.
Interesting note on the final (full season) chart. The two 20"+ winters that were above normal temps were due to HECS (1983, 2016). So, you want to have a full-season negative departure or you are praying for a fluke.