© Jennifer DicksonTree damage in Evergreen from Saturday’s derecho.
The storms produced several hurricane-force wind gusts, including a 110 mph gust in Winter Park, Colorado, according to the National Weather Service. Winds up to 99 mph were reported in Great Divide, Colorado, and 81 mph in Rock Springs, Wyoming. A 78 mph wind gust was reported at Denver International Airport.
Enough significant wind gusts were recorded on Saturday that a record was set for most significant wind gusts in one calendar day.
The derecho, a strong line of thunderstorms that produces hundreds of miles of straight-line wind damage, developed in far eastern Utah Saturday morning, then raced northeastward across Colorado and Wyoming into the western Dakotas and western Nebraska during the afternoon and evening hours, a track of at least 750 miles in about 12 hours, according to Elizabeth Leitman, a meteorologist with NOAA's Storm Prediction Center.
The line of storms formed on the southern flank of a developing low pressure system over the northern Rockies and southwestern Canada.
Derechos are common in June, but are rare in the Rockies where storms can have a more difficult time sticking together until they can reach the flatter plains to the east, where derechos are more common.
According to Leitman, there were only two other Western U.S. derechos documented prior to Saturday, in May 1994 and June 2002.
Video posted to social media showed a tree falling on a car in Denver.
More than 63,000 customers were without power as of about 9:30 p.m. EDT, according to poweroutage.us. Nearly 100,000 were without power earlier in the evening.
Photos showed widespread trees down and windows blown out of a home in Littleton.
There was also heavy rainfall, lightning and hail.
Comment: Another rare derecho killed three and cut power to half a million people across Pennsylvania and New Jersey last Wednesday.