Flash Flood in San Juan County, Utah

Significant flooding occurred due to heavy rains from a thunderstorm near Valley of the Gods and northeast of Mexican Hat. Fast moving waters covered Highway 163 near Valley of the Gods for a distance of 540 meters and 1 meter deep. Cottonwood Wash had major flood, surrounding house and filling flood plain. San Juan River spiked from 8.3 ft (2670 cfs) to 17.99 ft (20,700 cfs) near Mexican Hat. 28 people were trapped and stranded while on a river trip on the San Juan River where Lime Creek enters and eventually rescued. However, their boats and gear were swept away and lost in floodwaters.

Very deep tropical moisture associated with the remnants of Tropical Storm Alberto combined with monsoonal moisture was forced through eastern Utah and western Colorado due to a large high pressure ridge over the Central U.S. and a deep low pressure trough over the Great Basin. This deep moisture combined with strong instability and shear to produce widespread severe weather across eastern Utah and western Colorado with thunderstorms producing severe wind gusts, large hail and heavy rain which resulted in flash flooding and debris flows. One particular storm even produced a landspout tornado in southeast Utah. Frequent lightning also resulted in lightning damage in Montrose, Colorado.