In reply to PadreTed:
We were on Atlantic Slabs on Saturday, which has the same aspect but takes more drainage, and there was no sign of anything even vaguely resembling ice. There were a few tiny snow patches, but all were easily avoidable and despite temperatures being below freezing, they were all soft.
Conditions could well be different on Tryfan of course, and someone died on Bristly Ridge at the weekend (no idea of the circumstances)