Flash Flood in Grand County, Utah

Training thunderstorms produced upwards of 1 to 2 inches of rain within one to two hours in an around Moab. The Mill Creek Parkway - a recreational path that runs through the center of Moab, was reported to be 'completely decimated' as a result of the flooding. Several areas had their water turned off after flood waters led to a broken water main. Numerous homes and businesses had upwards of 12 inches of water and debris inside resulting in significant property damage.

A midlevel Pacific low pressure system undercut the area of high pressure over the Great Basin as it dropped into the Northern Rockies. Monsoon moisture increased across the region with precipitable water values ranging from 125 to 175% of normal across the Four Corners. Clearing conditions the morning of the 20th led to increased instability over southeast Utah which led to some stronger thunderstorms during the late evening hours. The anomalously high moisture values across the area resulted in heavy rain with thunderstorms. Additionally, winds aloft supported the training of thunderstorms. This heavy rainfall led to widespread flash flooding and debris flows across portions of Grand and San Juan counties.