Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 32, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Jul 21, 2021, 3:16 PM MDT for Grand County, Larimer County, Colorado. It was in force for 3 hr. 1 report came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Jul 21, 2021, 3:16 PM MDT (21:16 UTC)
- Expired
- Jul 21, 2021, 6:15 PM MDT
- In force
- 3 hr
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
Counties Grand County, CO, Larimer County, CO
The radar
The Denver radar (KFTG), 134 km from the middle of the area, began a volume at 21:18 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Jul 21, 3:25 PM MDT | FLASH FLOOD | 13 N Hot Sulphur Spring, CO | MULTIPLE DEBRIS FLOWS OVER CO-125 BETWEEN MILE MARKERS 10 AND 15, ROAD CLOSED AND SOME TRAVELERS STRANDED. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 9.3 hours before the alert went out and 238 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2182 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- -4 m²/s²
- 0-3 km storm-relative helicity
- 13 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
294
WGUS55 KBOU 212116
FFWBOU
COC049-069-220015-
/O.NEW.KBOU.FF.W.0032.210721T2116Z-210722T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
316 PM MDT Wed Jul 21 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
Northeastern Grand County in north central Colorado...
Southwestern Larimer County in north central Colorado...
* Until 615 PM MDT.
* At 316 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.4 and 0.8 inches of
rain have fallen. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
* Some locations that will experience flash flooding include...
Estes Park, Bear Lake, Grand Lake and Deer Ridge.
This includes the following streams and drainages...
Trout Creek, Columbine Creek, Cabin Creek, Ranger Creek, Onahu
Creek, Boulder Brook, Buffalo Creek, Round Creek, Willow Creek,
Drowsy Water Creek, Alpine Brook, Trail Creek, Corral Creek, Jack
Creek, Bighorn Creek, North Saint Vrain Creek, East Fork
Troublesome Creek, Middle Fork Creek, Illinois River, East Branch
Willow Creek, Roaring Fork, Colorado River, Tonahutu Creek, Hayden
Creek, Gold Run, Kinney Creek, Mc Queary Creek, Soda Creek, Icy
Brook, East Inlet, Big Thompson River, Echo Creek, Fraser River,
Wheatley Creek, Inn Brook, Pole Creek, Smith Creek, Wind River,
Monument Creek, Troublesome Creek, North Fork Cabin Creek, Spruce
Creek, Fall River, Ethel Creek, Aspen Brook, Glacier Creek and
North Inlet.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the North Inlet in the town of Grand Lake, the burned areas
on the west side of Rocky Mountain National Park, the Colorado River
above Shadow Mountain Reservoir, the Willow Creek valley along
Highway 125, Drowsy Water Creek, and the East Troublesome Creek
valley. Rock slides or debris flows can also be expected across
rural roads.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Spruce, Fern, and Mill Creek basins in Rocky Mountain
National Park. Rising water and debris may reach Moraine Park.
&&
LAT...LON 4039 10594 4036 10575 4042 10557 4026 10556
4026 10565 4025 10564 4023 10578 4010 10591
4010 10616 4017 10627 4026 10628 4033 10622
4033 10619 4034 10617 4033 10614 4035 10610
4035 10608 4037 10602 4035 10596 4037 10594
FLASH FLOOD...RADAR INDICATED
$$
RJK2 follow-up statements
937
WGUS75 KBOU 212139
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
339 PM MDT Wed Jul 21 2021
COC049-069-220015-
/O.CON.KBOU.FF.W.0032.000000T0000Z-210722T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-Larimer CO-
339 PM MDT Wed Jul 21 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 PM MDT THIS
EVENING FOR NORTHEASTERN GRAND AND SOUTHWESTERN LARIMER COUNTIES...
At 339 PM MDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 0.4 and 1.0 inch of rain has
fallen. Flash flooding is ongoing or expected to begin shortly. Law
enforcement indicated there were multiple mudslides along State Road
125 closing the road.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Law enforcement reported.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
Some locations that will experience flash flooding include...
Estes Park, Bear Lake, Grand Lake and Deer Ridge.
This includes the following streams and drainages...
Trout Creek, Columbine Creek, Cabin Creek, Ranger Creek, Onahu
Creek, Boulder Brook, Buffalo Creek, Round Creek, Willow Creek,
Drowsy Water Creek, Alpine Brook, Trail Creek, Corral Creek, Jack
Creek, Bighorn Creek, North Saint Vrain Creek, East Fork
Troublesome Creek, Middle Fork Creek, Illinois River, East Branch
Willow Creek, Roaring Fork, Colorado River, Tonahutu Creek, Hayden
Creek, Gold Run, Kinney Creek, Mc Queary Creek, Soda Creek, Icy
Brook, East Inlet, Big Thompson River, Echo Creek, Fraser River,
Wheatley Creek, Inn Brook, Pole Creek, Smith Creek, Wind River,
Monument Creek, Troublesome Creek, North Fork Cabin Creek, Spruce
Creek, Fall River, Ethel Creek, Aspen Brook, Glacier Creek and
North Inlet.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the North Inlet in the town of Grand Lake, the burned areas
on the west side of Rocky Mountain National Park, the Colorado River
above Shadow Mountain Reservoir, the Willow Creek valley along
Highway 125, Drowsy Water Creek, and the East Troublesome Creek
valley. Rock slides or debris flows can also be expected across
rural roads.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Spruce, Fern, and Mill Creek basins in Rocky Mountain
National Park. Rising water and debris may reach Moraine Park.
&&
LAT...LON 4039 10594 4036 10575 4042 10557 4026 10556
4026 10565 4025 10564 4023 10578 4010 10591
4010 10616 4017 10627 4026 10628 4033 10622
4033 10619 4034 10617 4033 10614 4035 10610
4035 10608 4037 10602 4035 10596 4037 10594
FLASH FLOOD...OBSERVED
$$
RJK564
WGUS75 KBOU 212341
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
541 PM MDT Wed Jul 21 2021
COC049-069-220015-
/O.CON.KBOU.FF.W.0032.000000T0000Z-210722T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-Larimer CO-
541 PM MDT Wed Jul 21 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 PM MDT THIS
EVENING FOR NORTHEASTERN GRAND AND SOUTHWESTERN LARIMER COUNTIES...
At 541 PM MDT, Doppler Radar law enforcement reported thunderstorms
producing heavy rain across the warned area. Between 0.4 and 1.2
inches of rain have fallen. Flash flooding is ongoing or expected to
begin shortly. Law enforcement indicating there were multiple
mudslides along State Road 125 closing the road.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Law enforcement reported.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
Some locations that will experience flash flooding include...
Estes Park, Bear Lake, Grand Lake and Deer Ridge.
This includes the following streams and drainages...
Trout Creek, Columbine Creek, Cabin Creek, Ranger Creek, Onahu
Creek, Boulder Brook, Buffalo Creek, Round Creek, Willow Creek,
Drowsy Water Creek, Alpine Brook, Trail Creek, Corral Creek, Jack
Creek, Bighorn Creek, North Saint Vrain Creek, East Fork
Troublesome Creek, Middle Fork Creek, Illinois River, East Branch
Willow Creek, Roaring Fork, Colorado River, Tonahutu Creek, Hayden
Creek, Gold Run, Kinney Creek, Mc Queary Creek, Soda Creek, Icy
Brook, East Inlet, Big Thompson River, Echo Creek, Fraser River,
Wheatley Creek, Inn Brook, Pole Creek, Smith Creek, Wind River,
Monument Creek, Troublesome Creek, North Fork Cabin Creek, Spruce
Creek, Fall River, Ethel Creek, Aspen Brook, Glacier Creek and
North Inlet.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the North Inlet in the town of Grand Lake, the burned areas
on the west side of Rocky Mountain National Park, the Colorado River
above Shadow Mountain Reservoir, the Willow Creek valley along
Highway 125, Drowsy Water Creek, and the East Troublesome Creek
valley. Rock slides or debris flows can also be expected across
rural roads.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the East Troublesome burn area. Some areas affected
include the Spruce, Fern, and Mill Creek basins in Rocky Mountain
National Park. Rising water and debris may reach Moraine Park.
&&
LAT...LON 4039 10594 4036 10575 4042 10557 4026 10556
4026 10565 4025 10564 4023 10578 4010 10591
4010 10616 4017 10627 4026 10628 4033 10622
4033 10619 4034 10617 4033 10614 4035 10610
4035 10608 4037 10602 4035 10596 4037 10594
FLASH FLOOD...OBSERVED
$$
RJKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 6:58 PM MDT | Flash Flood Warning | BOU | Larimer | 92 min |
| Jul 20, 7:09 PM MDT | Flash Flood Warning | BOU | Larimer | 81 min |
| Jul 21, 3:18 AM MDT | Flash Flood Watch | BOU | Boulder, Grand, Jackson, Larimer | 17 hr |
| Jul 21, 1:30 PM MDT | Flash Flood Warning | BOU | Larimer | 3 hr |
| Jul 21, 1:56 PM MDT | Areal Flood Advisory | BOU | Grand | 3 hr |
| Jul 21, 2:31 PM MDT | Areal Flood Advisory | BOU | Park | 119 min |
| Jul 21, 2:44 PM MDT | Special Weather Statement | BOU | Teller | 46 min |
| Jul 21, 2:47 PM MDT | Flash Flood Warning | BOU | Larimer | 103 min |
| Jul 21, 3:22 PM MDT | Areal Flood Advisory | BOU | Park | 69 min |
| Jul 21, 4:40 PM MDT | Areal Flood Advisory | BOU | Douglas | 65 min |
| Jul 21, 5:06 PM MDT | Flash Flood Warning | BOU | Clear Creek | 3 hr |
Nearby
Flash Flood Warnings in Colorado, 2021Every flash flood warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.