From Advent 2017 the Solemnities of the Epiphany and the Ascension will be restored to their traditional days, rather than being transferred to Sunday. However, if Epiphany (Jan 6th) falls on a Saturday, Sunday or Monday, (as it will do for the next three years) it will still be observed on Sunday. Ascension Day is always on a Thursday, forty days after Easter. These feasts are Holydays of Obligation.
More details here.