While I have only once been to the Summit County resorts in April, I agree with RobertW's assessment. You can anticipate any kind of weather, but the coverage is usually great. I remember going to Vail and being disappointed to see brown mud mixed in the snow at the base, but one I went up the first chair, there was nothing but snow. Conditions also greatly depend on the amount of snow the resorts get during the winter especially March, which determnines the base. This year the snowfall has been epic so far and the bases are greater than normal.
I have skied Snowbird and Alta in Uthahe in early April and never been disappointed. Bases usually 130" plus. But bring lots of suntan lotion and layered clothing since the temps might feel warm. In general you can expect a little more "scrunch" since the surface tends to go through freezing-thaw cycles much more frequently.
ENJOY!!! I am thinking of heading to Snowbird in early April.