Officials from Coconino County, Arizona, reported that record rainfall fell on August 17, 2021, causing severe flooding in the vicinity of Flagstaff.
In a statement on August 17, Coconino County said it started raining around noon near Flagstaff.
"By the time a major thunderstorm system left the area, the entire area of the scorched area (as a result of recent fires) was saturated with moisture, leading to the largest flood to date," the statement said. In the south of the oblast, an hourly rainfall of 3.07 inches (77.98 mm) was recorded.
“In addition, precipitation was intense: in 15 minutes, more than 1.14" was recorded on the southern and western gauges, and 1.06 "on the eastern gauge. Significant precipitation fell not only on the burned-out areas of the terrain, but also in the Sunnyside area. In an hour, 1.22 inches fell in Linda Vista, and 1.5 inches was recorded in areas downstream. The amount of precipitation recorded on the southern pressure gauge corresponds to a 200-500-year rainfall rate, "Coconino County said.
The rain that fell over the entire area burned by the fires, combined with significant rainfall in the vicinity, led to flooding, as a result of which roads were blocked and dams overflowed. A large amount of debris was seen in the storm waters, given that there had been no previous heavy rains in a large area where all vegetation was destroyed by fire.