In the Denver metro area, an Action Day for multiple pollutants is in effect until 4 p.m. Ozone will be in the unhealthy range for sensitive groups and while fine particulates from the western wildfires are dissipating slightly Tuesday, the prolonged exposure to them for people led to an extended health alert.
The Air Quality Index in Denver was 75 as of 9 a.m. and 80 in the Fort Collins area. Air quality is at “good” levels on the western side of the Continental Divide.
A flash flood watch also went into effect in the mountains west of the Divide, including Glenwood Canyon, at 10 a.m. as widespread showers fell across the area. It will be in effect until 10 p.m.
According to the Colorado Water Conservation Board, there is a moderate threat of flooding across the mountains, but the Cameron Peak and East Troublesome burn scars face a high impact threat Tuesday, and the Grizzly Creek burn scar faces a high threat.
#FBF: The #COflood threat is once again elevated over recent burn areas. A HIGH IMPACT flood threat has been issued for the #CameronPeak & #EastTroublesome burn areas. A HIGH flood threat is issued for #GrizzlyCreek. Stay tuned into your local NWS office for the latest. #COwx pic.twitter.com/YOvHMcwjh1— CO Flood Updates (@COFloodUpdates) August 3, 2021
The National Weather Service said heavy rain is possible before noon in the mountains of Jackson, Grand, Summit and Park counties and that rain could persist through the day.
Flood advisories were issued for northeastern Grand County until 11:15 a.m. and for central Eagle County until 12:30 p.m. after more than a half-inch of rain fell Tuesday morning.
A mudslide at approximately 4:48 p.m. in Grand County on Highway 125 caused a shutdown around mile marker 11.5. The highway will stay closed overnight.
There is a lower chance of storms east of the Divide, with a chance of storms possible in the metro area and plaints Tuesday evening.
The monsoon moisture that has persisted across the state for the past month or so has helped tamp down drought conditions in the western half of Colorado but has also led to widespread flash flooding and mudslides across the state.
Interstate 70 through Glenwood Canyon is expected to be closed for “days to weeks” before it can reopen after it was buried by up to 10 feet of mud last week during flash flooding on the Grizzly Creek burn scar that severely damaged the interstate and viaduct.
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