Even within Eastern Loudoun, there are little micro climates. Very consistently, going from 400ft on belmont Ridge to the airport at 300ft, there's a difference. Not so much noticeable right after the snow stops, but definitely noticeable after a few days once the snow starts to melt. Very common for snow to hang on in the shadows at 400ft while it's about gone at 300ft, 5 miles away, a week after the storm.