Flash Flood in Mesa County, Colorado

A strong to severe thunderstorm tracked down the Colorado National Monument, across the Redlands, portions of downtown Grand Junction and over the Grand Junction Regional Airport. The GJT ASOS at the Grand Junction Regional Airport recorded 1.07 inches of rain with rainfall rates of 1 inch in 30 minutes and there were several reports of hail/accumulation of hail. Heavy rain resulted in 6 to 8 inches of water running over some downtown Grand Junction streets, in parking lots and topping the curbs. There was standing water along River Road with lots of small hail contributing to drainage issues. Leach Creek near Catalina Drive filled with debris once water reached the HOA, resulting in flooding.

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.