A flash flood warning was issued by the National Weather Service in Salt Lake City for the Cottonwood burn scar in Beaver County on July 19. The alert, which was active until 8:00 PM MDT, warned of life-threatening flash flooding caused by thunderstorms producing heavy rain.
At 2:10 PM MDT, Doppler radar indicated that thunderstorms were producing heavy rain over the Cottonwood burn scar in east central Beaver County. Between 0.5 and 1.5 inches of rain had fallen at the time of the warning.
Officials stated that excessive rainfall over the burn scar would result in a debris flow moving through the Beaver River and eventually downstream into the Grove area within Beaver. This debris flow could consist of mud, rock, vegetation, and other loose materials.
The storm was also beginning to build into the South Fork of North Creek. While the debris flow had not yet reached the upper camera in Beaver Canyon at the time of the alert, officials noted that once it reached the upper camera at the diversion dam, the flow would be expected to reach the Grove area approximately 1 to 1.5 hours later.
The warning identified life-threatening flash flooding as a primary hazard for areas in and around the Cottonwood burn scar. Specific locations expected to experience flash flooding included Beaver, including the Grove area.
