As we inch closer and closer to a very cold snow system we start to watch the dry air aloft and down at the surface and see if we havr to make a few adjustments. The GFS has been decent this winter in the short range and plays the lower end of the snow predictions. The NAM has been the highest and the European model sits in the middle of the NAM and GFS.
The radar will slowly fill in tonight and for most of the area it shouls start between 9-11pm. Some areas of Virginia are showing those dry slots but at the same time we are getting banding features of a vort max and isentropic lift. This makes for a lot of local accumualtions changing from city to city. The dry air takes away from of the snow totals but the banding or bursts of snow make up for those dry areas.