Radar estimated precipitation amounts key in on both of those areas reaching over 1.5 inches in the Sugarhouse area and nearly 2 inches near Draper.
Gauge-measured rainfall amounts since midnight as reported to the National Weather Service include 2.38" at Sugarhouse near Parleys Way, 1.35" at our mountain meteorology lab on the University of Utah campus, and 1.20 inches in Draper.
Contrasts between radar estimated and gauge-measured precipitation are not uncommon and careful analysis will be needed to identify the magnitude of peak precipitation amounts. Nevertheless, it is clear from both Sugarhouse and Draper received an impressive amount of rain for such a short period of time. Data from the National Weather Service Precipitation Frequency Data Server (https://hdsc.nws.noaa.gov/hdsc/pfds/) suggests that in the Sugarhouse area, precipitation amounts of about 2 inches in 6 hours have a return interval of 100 years.
Additionally, precipitation fell in somewhat less than six hours and probably was especially intense in short bursts. Local news media reports some flooded basements, road closures, power outages, and transit disruptions.
A quick word on recurrence intervals. Perhaps most importantly is that they are estimates of the recurrence of precipitation at a point, not in an area. Hence, given the chaotic and localized nature of thunderstorms, we might expect a storm like this to strike somewhere in the Salt Lake Valley more frequently than every 100 years.