Why the backwards storm? It was an event with large-scale southeasterly to easterly flow, as can be seen in the movement of precipitation features in the radar loop below, which covers most of the event.
The backwards storm isn't all that uncommon. They happen a few times each winter. Given the meager snowpack, I'm sure the Park City folks are glad to get it.
Addendum @ 10:00 AM
The NWS has posted some snow totals and those from the central Wasatch show the east-west snowfall gradient quite well.