Debris Flow in San Juan County, Colorado

Heavy rain from thunderstorms occurred in the early morning hours of June 21 and caused a major rock slide that damaged part of the railroad track for the Durango to Silverton Narrow Gauge Railroad. Exact time of occurrence is estimated. Part of the 45-mile long railroad track was blocked by a pile of debris after a rock slide occurred. Officials were notified about the rock slide just after 7:30 a.m. MDT that morning. The rock slide happened near mile post 486 just outside Needleton, which is about 55 minutes south of Silverton by train.

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.