Pray heavily. The roads into/out of Jerusalem are all closed. The snow is only meant to intensify and they've been speaking about this for a while.

Do you read Hebrew? If so, I recommend staying appraised of Hebrew media.

Regardless, if I were you, I'd be ready to leave right now and get ready to go the moment the roads open up (if they do), because no one knows if that will stay. If need be, try to find a place to stay tonight.

What airline are you flying? There's a good chance they will have a waiver in place to allow you to change your ticket for free if needed.

I remember the storm from last year, and was in Jerusalem and Gush Etzion for it. Unfortunately, I don't have high hopes that it will open soon