Someone was going to get a beating from the ongoing monsoon surge and right now it is Phoenix. Observations from the Phoenix International Airport (KPHX) show that 3.09" of rain has fallen since midnight.
The NWS has issued flash flood warnings for much of the area.
The 1200 UTC (0600 MDT) analysis below shows the mix of airstreams feeding the storm system, known as a mesoscale convective system, this morning. Potentially contributing to this event are moisture sources associated with Tropical Cyclone Norbert, a Gulf of California surge, and even the Gulf of Mexico, although the juiciest air appears to be originating from the Pacific and the Gulf of California.
The potential for thunderstorms that could be locally heavy exists across much of Utah today through tomorrow. Keep an eye to the sky. NWS forecasts at http://www.wrh.noaa.gov/slc/.