This is not just a Utah thing.
Notice that in Seattle itself the prices have only gone up about 4%. But in the surrounding area - i.e. suburbs - they have gone up dramatically. Looks like one component is the high paid tech workers that have been in the downtown Seattle area are buying homes in the suburbs.
I think another component is that baby boomers have lots of investments and are looking for better returns than their bonds are getting. They are worried about inflation, etc. So they are looking at inflation hedges with real estate being one of those. With all the all-cash offers we are seeing it seems to me that these investment companies are throwing money around chasing lower inventories.