Heavy rain produced a debris flow that impacted CO-125 near Mile Marker 7 in the East Troublesome burn area. A USFS vehicle was entrapped in a mud/debris flow on Cabin Creek Road.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS BOU wrote it up.
Heavy rain produced a debris flow that impacted CO-125 near Mile Marker 7 in the East Troublesome burn area. A USFS vehicle was entrapped in a mud/debris flow on Cabin Creek Road. It partially buried his vehicle. The employee was safe and uninjured. Localized flash flooding also occurred along Kinney Creek in the Williams Fork burn area.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Denver/Boulder, CO wrote its last area forecast discussion before the first event at Jul 22, 1:49 PM MST, 51 minutes earlier.
Area Forecast Discussion National Weather Service Denver/Boulder CO 249 PM MDT Thu Jul 22 2021 .SHORT TERM...(This evening through Friday) Issued at 223 PM MDT Thu Jul 22 2021 Weak flow aloft tonight will be over the region with the upper ridge centered around the Four Corners, and a closed upper low over west TX. Some minor flooding issues in the Cameron Peak burn areas this afternoon. The latest HRRR runs continue to generate thunderstorms over the mountains and foothills this afternoon, then shift some of those storms eastward into the urban corridor by early this evening. Precipitable water values not as high as yesterday, but still enough to produce moderate to heavy rainfall coupled with the slower storm motions. Threat will increase over all the burn areas on Friday, as models continue to show an uptick in the precipitable water values Friday afternoon, with subtropical moisture increasing over the forecast. On Friday, the upper low will shift slightly northwestward as will the center of the ridge as it moves over central UT. This will result in a continued weak north/northeast flow regime in the mid levels. Another warm afternoon on tap with high temperatures in the mid 90s once again. Storm motions weak on Friday, with 700/500 mb layer winds less than 10 kts. Mixing ratios in this same layer around 6 g/kg this aftn increase to 8 g/kg over the high elevation areas Friday aftn. Heavy rain will be a threat everywhere by late in the day, but the biggest threat will be over the burn area which is where the flash flood watch in effect. .LONG TERM...(Friday night through Thursday) Issued at 223 PM MDT Thu Jul 22 2021 An elongated upper level ridge of high pressure will stretch from Central California into the Southern Plains States Friday night through Sunday with an easterly wave moving west across the Desert Southwest. Abundant monsoonal moisture will still remain in place over Colorado with PW's ranging between 0.75" to 1.00" in the high country and 1.00" to 1.50" on the plains through Saturday. Values are expected to decrease somewhat on Sunday, but will still be anomalously high. In addition, a weak cool front moving across Northeastern Colorado will bring slightly cooler temperatures and weak upslope flow east of the mountains on Saturday. Therefore, it looks like there is a good chance that the 90 day streak will end. This pattern should produce isolated to scattered showers and storms across the plains with scattered to numerous showers and storms over the high country. The storms will be slow moving and capable of producing locally heavy rain and flash flooding, especially across the burn areas. At this time it looks like the greatest risk for flash flooding will be Friday night and Saturday with a lower risk on Sunday. Drier weather is expected Monday through Thursday as the upper ridge builds over the Rocky Mountain Region and Central Plains States. The plains should be mostly dry through this period with above normal temperatures. Max temperatures will be in the 90s each day with possibly reaching a 100 degrees in some locations Tuesday and Wednesday. The mountains will continue to see scattered afternoon showers and storms each day through the period. && .AVIATION...(For the 18Z TAFS through 18Z Friday afternoon) Issued at 223 PM MDT Thu Jul 22 2021 VFR through the TAF period. Typical diurnal wind patterns are expected tonight. There is a 10-20 percent of a shower or storm moving near KDEN late this afternoon and early evening. Some gusty winds up to 30 mph would be possible if the showers and storms were to move close to the terminal. North to northeast winds on Friday will develop in the morning and continue in the afternoon, with a better chance of thunderstorms after 21z, with at the potential for ILS restrictions with the thunderstorms. && .HYDROLOGY... Issued at 223 PM MDT Thu Jul 22 2021 There will be an elevated risk of flash flooding for burn areas on Friday, with a low risk of flooding elsewhere. Increased moisture and slow moving storms will create a higher risk of heavy rain. Abundant moisture and slow moving storms will create the potential for heavy rain and flash flooding Friday night through Sunday. The greatest risk for flash flooding will be Friday evening and then again on Saturday, especially over the burn areas. The risk will be somewhat lower on Sunday due to a decrease in monsoonal moisture. For Monday through Thursday, warmer temperatures are expected with a lesser chance of showers and storms. However, there may still be a low risk for flash flooding across the burn areas any of these days. && .BOU WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Friday afternoon through Friday evening for COZ033>035. && SHORT TERM...Cooper LONG TERM...Kalina AVIATION...Cooper HYDROLOGY...Cooper
Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1102 AM MDT Thu Jul 22 2021 COZ030>051-231715- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 1102 AM MDT Thu Jul 22 2021 This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight Thunderstorm coverage will decrease over the I-25 corridor and plains today with slightly drier air in place. There will be better coverage of thunderstorms along and west of the Continental Divide. These storms will be capable of producing heavy rain which may lead to flash flooding in the Cameron Peak, East Troublesome, and Williams Fork burn areas. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Thunderstorm activity will increase Friday with an elevated threat of flash flooding on the burn areas through Saturday. Localized heavy rain is possible elsewhere with a low risk of flooding. For Sunday through Wednesday, there will be a drying trend with hot temperatures. There will still be a low risk of burn scar flooding Sunday, then the risk will be very low for the early part of next week. Temperatures could be near 100 again on the plains by Tuesday. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today or tonight, however, rainfall reports from the burn scars would be appreciated.
The Denver radar (KFTG), 131 km away, was scanning. The volume nearest the first event began at 21:40 UTC.
2 flash flood. Local standard time, as filed.
Heavy rain produced localized flash flooding along Kinney Creek. There was some damage to the road. The floodwaters also impacted nearby properties.
Heavy rain produced a debris flow that impacted CO-125 near Mile Marker 7. County Road 21 was also flooded near its confluence. The debris flow forced the closure of the highway until it could be cleared. A mud/debris flow in the Cabin Creek drainage partially buried a parked USFS vehicle, and trapped the employee behind a washed-out road. The Forest Service employee was assessing one of the closed forest service roads when the storm hit, he was found safe and uninjured.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Colorado in 2021Every state in 2021This day in weather historyWarnings in Colorado, July 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 975401, 971675.