Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 63, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Aug 2, 2021, 4:11 PM MDT for Larimer County, Colorado. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 2, 2021, 4:11 PM MDT (22:11 UTC)
- Expired
- Aug 2, 2021, 7:15 PM MDT
- In force
- 3 hr
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
County Larimer County, CO
The radar
The Cheyenne radar (KCYS), 101 km from the middle of the area, began a volume at 22:13 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.
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 10.2 hours before the alert went out and 236 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
- 1582 m above ground
- 0-6 km bulk shear
- 10 kt
- 0-1 km storm-relative helicity
- -13 m²/s²
- 0-3 km storm-relative helicity
- 34 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
123
WGUS55 KBOU 022211
FFWBOU
COC069-030115-
/O.NEW.KBOU.FF.W.0063.210802T2211Z-210803T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
411 PM MDT Mon Aug 2 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
West Central Larimer County in north central Colorado...
* Until 715 PM MDT.
* At 411 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.5 and 0.75 inches of
rain has fallen. Additional rainfall amounts up to 0.5 inches are
possible in the warned area. 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...
mainly rural areas of West Central Larimer County
This includes the following additional locations...
The Upper Poudre Canyon, The Laramie River Road near Chambers Lake
and Remote areas in the Cameron Peak Wilderness.
This includes the following streams and drainages...
Two and One Half Creek, Joe Wright Creek, Sheep Creek, Cache La
Poudre River, Laramie River, North Fork West Branch Laramie River
and Brinker Creek.
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 affected part of the Cameron Peak burn area. Rock
slides or debris flows can also be expected across rural roads.
&&
LAT...LON 4070 10589 4071 10578 4068 10568 4064 10569
4059 10578 4063 10584 4062 10589 4067 10591
FLASH FLOOD...RADAR INDICATED
$$
RPK2 follow-up statements
800
WGUS75 KBOU 022251
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
451 PM MDT Mon Aug 2 2021
COC069-030115-
/O.CON.KBOU.FF.W.0063.000000T0000Z-210803T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
451 PM MDT Mon Aug 2 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 715 PM MDT THIS
EVENING FOR WEST CENTRAL LARIMER COUNTY...
At 451 PM MDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. 1 inch of rain has fallen. Additional
rainfall amounts up to 0.5 inches are possible in the warned area.
Flash flooding is ongoing or expected to begin shortly.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
Some locations that will experience flash flooding include...
mainly rural areas of West Central Larimer County
This includes the following additional locations...
The Upper Poudre Canyon, The Laramie River Road near Chambers Lake
and Remote areas in the Cameron Peak Wilderness.
This includes the following streams and drainages...
Two and One Half Creek, Joe Wright Creek, Sheep Creek, Cache La
Poudre River, Laramie River, North Fork West Branch Laramie River
and Brinker Creek.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the affected part of the Cameron Peak burn area. Rock
slides or debris flows can also be expected across rural roads.
&&
LAT...LON 4070 10589 4071 10578 4068 10568 4064 10569
4059 10578 4063 10584 4062 10589 4067 10591
FLASH FLOOD...RADAR INDICATED
$$
RPK472
WGUS75 KBOU 030109
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
709 PM MDT Mon Aug 2 2021
COC069-030119-
/O.EXP.KBOU.FF.W.0063.000000T0000Z-210803T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
709 PM MDT Mon Aug 2 2021
...FLASH FLOOD WARNING WILL EXPIRE AT 715 PM MDT THIS EVENING FOR
WEST CENTRAL LARIMER COUNTY...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
A Flash Flood Watch remains in effect until 1000 PM MDT for Portions
of central and north central Colorado.
LAT...LON 4070 10589 4071 10578 4068 10568 4064 10569
4059 10578 4063 10584 4062 10589 4067 10591
$$
RPKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 2, 2:40 PM MDT | Areal Flood Advisory | BOU | Grand | 95 min |
| Aug 2, 3:38 PM MDT | Areal Flood Advisory | BOU | Grand | 82 min |
| Aug 2, 3:47 PM MDT | Flash Flood Warning | BOU | Jackson, Larimer | 3 hr |
| Aug 2, 4:16 PM MDT | Areal Flood Advisory | BOU | Grand | 89 min |
| Aug 2, 5:08 PM MDT | Areal Flood Advisory | BOU | Boulder, Grand | 82 min |
| Aug 2, 5:14 PM MDT | Areal Flood Advisory | BOU | Larimer | 91 min |
| Aug 2, 5:18 PM MDT | Areal Flood Advisory | BOU | Park | 87 min |
| Aug 2, 5:40 PM MDT | Areal Flood Advisory | BOU | Boulder, Grand, Larimer | 95 min |
| Aug 2, 5:57 PM MDT | Areal Flood Advisory | BOU | Larimer | 93 min |
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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.