This happened to me several years ago. Had heavy wet snow fall temp well below freezing a few days before I drove anywhere. Figured streets ought to be clear, no worries. Going down long hill and not going very fast cue to red light at bottom of hill. A dip pulled out of side street at snail pace had to hit my brakes hard.
Most all the snow came off, it was a Chevy high top van we had at time. Been driving awhile and heat in van had helped melt layer of ice under the snow.
All the snow and ice slid off the roof down the windshield taking both windshield wipers arms and all. Talk about a mess!
So get you a long handled whatever, back then we took a shop brush and clear what you can away.
"Good Luck!"