I've had an opportunity to dig in a little deeper to the deluge that hit the Sugarhouse area early Wednesday morning.
Storm-total precipitation was greatest at a citizen weather station between Foothill Drive and Parley's Way near the mouth of Parley's Canyon. Maximum precipitation rates at the site were 1.64 inches in 30 minutes, 2.28 inches in 60 minutes, 2.39 inches in 2 hours, and 2.41 inches in 3 hours. If accurate, those all have recurrence intervals near 200 years, as also reported by Salt Lake City Public Utilities.
Soundings collected at the Salt Lake City airport at about 6 AM either during or in the wake of the storm (depending on when the sounding was actually released) showed a precipitable water value of 1.41 inches. Precipitable water is the depth of water that you would have if you condensed all of the water vapor out of an atmospheric column. Such values are high, as one would expect in a flash-flood scenario, but not unprecedented, as illustrated by the chart below (red line represents the daily highest value). The all time record is 1.66 inches.
Radar imagery shows very nicely how a well-defined band of precipitation developed early in the event and extended from WSW to ENE across the Sugarhouse area.
Below is a radar estimate of the 3-hour accumulated precipitation (inches) for the period ending at 1109 UTC (0509 MDT), which captures most of the precipitation. Note the banded area of high precipitation with a maximum located along Foothill Drive just south of campus where values exceed 1.5 inches.
The southern diamond is the site that observed 2.41 inches, the northern diamond covers our sites near the mouth of Red Butte Canyon where 1.33 and 1.21 inches were observed from midnight to 6 AM. The former is much higher than the radar estimates, whereas the latter are closer. Further sleuthing is needed to reconcile the differences.
Any observations from the area along I-15 just north of the Point of the Mountain that also appeared to get pounded (with even more precipitation)? I'm curious what happened there.