Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 30, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Jul 21, 2021, 1:30 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
- Jul 21, 2021, 1:30 PM MDT (19:30 UTC)
- Expired
- Jul 21, 2021, 4:30 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), 82 km from the middle of the area, began a volume at 19:32 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, 7.5 hours before the alert went out and 204 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.
635
WGUS55 KBOU 211930
FFWBOU
COC069-212230-
/O.NEW.KBOU.FF.W.0030.210721T1930Z-210721T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
130 PM MDT Wed Jul 21 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
Central Larimer County in north central Colorado...
* Until 430 PM MDT.
* At 130 PM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the Cameron Peak burned 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...
Western Fort Collins, Pennock Pass, Stove Prairie, Glen Haven,
Buckhorn Mountain, Drake, Pingree Park, Rustic, Masonville and
Horsetooth Mountain.
This includes the following additional locations...
Box Prairie, Upper Buckhorn along County Road 44H, Moondance Way,
Stringtown Gulch, Big Bear, Lower Buckhorn on County Road 27 above
Masonville, Crystal Mountain, Poudre Springs, Monument Gulch, Jacks
Gulch, Upper Pingree Park Road, Lower Pingree Park Road, Sky Ranch,
Gulches along Highway 14 near and above Rustic, Rising water and
large debris in the Poudre River, Pingree Hill, Goodell Corner, The
Retreat and Storm Mountain.
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 4075 10558 4056 10515 4041 10519 4048 10571
FLASH FLOOD...RADAR INDICATED
$$
RJK3 follow-up statements
783
WGUS75 KBOU 212007
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
207 PM MDT Wed Jul 21 2021
COC069-212230-
/O.CON.KBOU.FF.W.0030.000000T0000Z-210721T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
207 PM MDT Wed Jul 21 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 430 PM MDT THIS
AFTERNOON FOR CENTRAL LARIMER COUNTY...
At 207 PM MDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Doppler radar indicated between 0.3 and
0.6 inches of rain have fallen. Flash flooding is ongoing or
expected to begin shortly. The storms producing the rain were
moving east-southeast at 10 mph.
HAZARD...Flash flooding caused by thunderstorms.
SOURCE...Radar.
IMPACT...Flash flooding of small creeks and streams, gulches,
roads, and poor drainage and low-lying areas.
Some locations that will experience flash flooding include...
Western Fort Collins, Pennock Pass, Stove Prairie, Glen Haven,
Buckhorn Mountain, Drake, Pingree Park, Rustic, Masonville and
Horsetooth Mountain.
This includes the following additional locations...
Box Prairie, Upper Buckhorn along County Road 44H, Moondance Way,
Stringtown Gulch, Big Bear, Lower Buckhorn on County Road 27 above
Masonville, Crystal Mountain, Poudre Springs, Monument Gulch, Jacks
Gulch, Upper Pingree Park Road, Lower Pingree Park Road, Sky Ranch,
Gulches along Highway 14 near and above Rustic, Rising water and
large debris in the Poudre River, Pingree Hill, Goodell Corner, The
Retreat and Storm Mountain.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
Heavy Rainfall will cause flash flooding of small creeks, streams,
and ditches in the affected part of the Cameron Peak burn area. Rock
slides or debris flows can also be expected across rural roads.
&&
LAT...LON 4075 10558 4056 10515 4041 10519 4048 10571
FLASH FLOOD...RADAR INDICATED
$$
RJK098
WGUS75 KBOU 212135
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
335 PM MDT Wed Jul 21 2021
COC069-212230-
/O.CON.KBOU.FF.W.0030.000000T0000Z-210721T2230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
335 PM MDT Wed Jul 21 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 430 PM MDT THIS
AFTERNOON FOR CENTRAL LARIMER COUNTY...
At 335 PM MDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 0.3 and 0.7 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...
Western Fort Collins, Pennock Pass, Stove Prairie, Glen Haven,
Buckhorn Mountain, Drake, Pingree Park, Rustic, Masonville and
Horsetooth Mountain.
This includes the following additional locations...
Box Prairie, Upper Buckhorn along County Road 44H, Moondance Way,
Stringtown Gulch, Big Bear, Lower Buckhorn on County Road 27 above
Masonville, Crystal Mountain, Poudre Springs, Monument Gulch, Jacks
Gulch, Upper Pingree Park Road, Lower Pingree Park Road, Sky Ranch,
Gulches along Highway 14 near and above Rustic, Rising water and
large debris in the Poudre River, Pingree Hill, Goodell Corner, The
Retreat and Storm Mountain.
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 4075 10558 4056 10515 4041 10519 4048 10571
FLASH FLOOD...RADAR INDICATED
$$
RJK924 WGUS75 KBOU 212225 FFSBOU Flash Flood Statement National Weather Service Denver CO 425 PM MDT Wed Jul 21 2021 COC069-212235- /O.EXP.KBOU.FF.W.0030.000000T0000Z-210721T2230Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ Larimer CO- 425 PM MDT Wed Jul 21 2021 ...FLASH FLOOD WARNING WILL EXPIRE AT 430 PM MDT THIS AFTERNOON FOR CENTRAL LARIMER COUNTY... The heavy rain has ended over the Cameron Peak burn area. Flooding is no longer expected to pose a threat. Please continue to heed remaining road closures. A Flash Flood Watch remains in effect until 800 PM MDT for A portion of north central Colorado. LAT...LON 4075 10558 4056 10515 4041 10519 4048 10571 $$ RJK
The 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, 1:56 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, 3:16 PM MDT | Flash Flood Warning | BOU | Grand, Larimer | 3 hr |
| 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.