Powerful Pacific System Impacting the West; First Significant Snow for Portions of the East

Power Pacific system will continue to bring significant impacts for Pacific Northwest into northern California the remainder of the week. Dangerous coastal affects, heavy rain, flooding, strong winds, and higher elevation mountain snow continues. Meanwhile, a storm across the east is set to bring the first accumulating snow to many higher elevations of the Catskills into the central Appalachians. Read More >

Overview

Northerly flow persisted across the western slope of Colorado during the weekend of June 26-27, 2021 on the backside of a departing trough of low pressure. Residual moisture paired with moderate instability led to isolated to scattered showers and thunderstorms along the Continental Divide during the afternoon and evening hours as available moisture was over 130% of the climatological normal. Additionally, weak winds aloft resulted in slow storm motion.

All of these elements resulted in showers and thunderstorms that were producing heavy rainfall with some storms exceeding 0.50 to 1.00 inches per hour. As a result, significant debris flows occurred on the Grizzly Creek Fire burn scar near Glenwood Springs, Colorado, and along Interstate 70 in particular during the afternoon hours on June 26th, and then again on June 27th. I-70 was closed for about 7 hours due to debris cleanup on the 26th and for a full day after the flow on the 27th.

Rainfall totals were estimated at 0.30 to 0.40 inches on Saturday the 26th which led to a debris flow that spread 70 feet wide and was up to 5 feet deep in areas. Sunday's rainfall totals were estimated at 0.40 to 0.60 inches which led to a flow that was 2 to 3 times larger than Saturday's. The debris flow on Sunday the 27th also covered both sides of the interstate.

Debris Flow on I-70 on June 27th
Ariel footage of debris flow across Interstate 70 on June 27th

(Glenwood Springs Fire Department)


Debris on I-70 on June 27th (CDOT)	Debris on I-70 on June 27th (Post Independent)	Debris on I-70 on June 27th

Radar
Photos

Radar

Radar footage and precipitation estimates from June 26th and June 27th


Radar Loop on June 26th (NWS)	Estimated Precipitation on June 26th	Radar Loop on June 27th (NWS)	Estimated Precipitation on June 27th

Photos

Photos from both debris flow events on June 26th and June 27th


Debris on I-70 on June 27th (CDOT)	Debris on I-70 on June 26th (KDVR)	Debris on I-70 on June 26th (KDVR)	Debris on I-70 on June 26th (KDVR)

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Powerful Pacific System Impacting the West; First Significant Snow for Portions of the East

June 26-27, 2021 Grizzly Creek Debris Flows