At the end of our winter trip last weekend we hitch the trailer. I'd brushed 4-5" of snow from the top of the hitch thinking that was good enough.
For some reason (might be the -10F) I gave things 1 more extra hard tug than I usually do to check that the hitch was coupled....it wasn't.
The snow I left inside the jaws was enough to prevent the jaws from locking.
We pulled the trailer at 40mph in 4x4 high (4x4 makes towing in the snow much much better) when a semi passed us. Felt kind of stupid thinking that professional drivers are much better winter drivers but 15min later we found him in a snow bank.