Park City has some kind of invisable wall that keeps an open hole of sun above the resort. No joke, there have been days where it is suppose to be cloudy or mostly cloudy and down in slc it is cloudy, but you go up to PC and there is a blue hole above it. It will be cloudy sometimes though. But usually from march on it is sunny alot. I think in jan-feb we had alot of cloudy days, but it was always snowing.
i went to PC for 8 days this past january and i had 2 or 3 sick pow days (one at alta one at PC) a couple days of bluebird that was perfect for park riding, and only like 1 day where it was cloudy all day. PC is amazing and has really good weather for skiing.