SPM 08-04-2021: Flooding Reported in Southwest Slope and Vulnerable Burn Scars

Issue Date: Wednesday, August 4th, 2021
Issue Time: 10:15 AM MDT

Summary:

There was an early start to the rainfall yesterday, especially in the Northern and Central Mountains. Flood advisories and flash flood warnings were issued across the state, including several fire burn scars. Cameron Peak, East Troublesome, Grizzly Creek, and Spring Creek have been especially vulnerable this year as they were recent fires, but Hayman-Teller, High Park, and Lake Christine burn scars also had heavy rain and flood warnings issued.

I-70 has remained closed after damaging debris flows this past weekend near the Grizzly Creek burn scar, and additional rain yesterday was likely unhelpful in the cleanup effort. Matt Minnillo shared the following screen grab of a CDOT road camera from yesterday which shows water flowing over the interstate again. Over an inch of rain fell near Dotsero yesterday.

More water and debris flowing onto I-70 in the Grizzly Creek burn scar area. Nothing new, just interesting to see live on traffic cams. #cowx pic.twitter.com/chds6viOzj

— Matt Minnillo (@MattBlueThunder) August 3, 2021

CO125 was also closed yesterday north of Highway 40 along Grand and Jackson counties due to a mud flow adjacent to East Troublesome burn scar. A USGS gauge on East Troublesome Creek reported 0.39 inches yesterday. Even higher totals, between 0.64-1.24 inches, were reported just east of the slide around Lake Granby

In the southwest slope, flooding was reported in Placerville:
SAN MIGUEL SHERIFFS OFFICE REPORTS TWO MUDSLIDES ON HIGHWAY 145 AT MILE MARKERS 85 AND 86 JUST NORTH OF JUNCTION OF HIGHWAY 62 AND HIGHWAY 145. REPORTS OF 2 FEET OF DEBRIS ACROSS THE ROADWAY AT MILE MARKER 86.
A Weather Underground PWS in Placerville reported 1.35 inches of rain yesterday, with a peak rainfall rate over 4.5 inches per hour!

As the day progressed, storms spilled over onto Eastern Plains, aided by the passage of the slow-moving trough, resulting in the North-South orientation of rainfall across the state, seen in the map below. Some notable rainfall totals include:

1.61 inches in Agate (Elbert County)
1.58 inches in the Pinery (Douglas County), where a CoCoRaHS observer remarked that 1.49 inches of that fell in just an hour and half!
1.52 inches in Franktown (Douglas County)
1.15 inches in Byers (Arapahoe County)

For rainfall estimates in your area, check out the State Precipitation Map below.

Click Here For Map Overview

The map below shows radar-estimated, rainfall gage-adjusted Quantitative Precipitation Estimates (QPE) across Colorado. The map is updated daily during the operational season (May 1 – Sep 30) by 11AM. The following six layers are currently available: 24-hour, 48-hour and 72-hour total precipitation, as well as maximum 1-hour, 2-hour and 6-hour precipitation over the past 24 hour period (to estimate where flash flooding may have occurred). The accumulation ending time is 7AM of the date shown in the bottom right corner. Also shown optionally are vulnerable fire burn areas (post 2012), which are updated throughout the season to include new, vulnerable burn areas. The home button in the top left corner resets the map to the original zoom.