Use 'snowed up' to describe situations where snow physically prevents movement or access. The cabin was snowed up after the blizzard, leaving us stranded.
Pro Tip 2/3
Temporary State
'Be snowed up' implies a condition that is expected to be resolved once snow is cleared. The airport runway was snowed up but should reopen tomorrow.
Pro Tip 3/3
Immobility
It's often used to suggest that someone is stuck in a place due to heavy snow. We were snowed up at the ski lodge, with no way to leave.