Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 57, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Jul 31, 2021, 2:16 PM MDT for Larimer County, Colorado. It was in force for 89 min. 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 31, 2021, 2:16 PM MDT (20:16 UTC)
- Expired
- Jul 31, 2021, 3:45 PM MDT
- In force
- 89 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
County Larimer County, CO
The radar
The Cheyenne radar (KCYS), 88 km from the middle of the area, began a volume at 20:18 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.
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 8.3 hours before the alert went out and 202 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
- 44 J/kg
- Mixed-layer CIN
- -277 J/kg
- Mixed-layer LCL
- 1127 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- -71 m²/s²
- 0-3 km storm-relative helicity
- -21 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
950
WGUS55 KBOU 312016
FFWBOU
COC069-312145-
/O.NEW.KBOU.FF.W.0057.210731T2016Z-210731T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
216 PM MDT Sat Jul 31 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
South Central Larimer County in north central Colorado...
* Until 345 PM MDT.
* At 216 PM MDT, Doppler radar indicated heavy rain across the
warned area. Up to 0.5 inches of rain have fallen. Additional
rainfall amounts up to 0.25 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...
Glen Haven, Drake, Pennock Pass and Cedar Cove.
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, 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 4059 10553 4058 10527 4041 10525 4042 10552
4057 10555
FLASH FLOOD...RADAR INDICATED
$$
RPK2 follow-up statements
501
WGUS75 KBOU 312055
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
255 PM MDT Sat Jul 31 2021
COC069-312145-
/O.CON.KBOU.FF.W.0057.000000T0000Z-210731T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
255 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 345 PM MDT THIS
AFTERNOON FOR SOUTH CENTRAL LARIMER COUNTY...
At 255 PM MDT, Emergency management reported producing heavy rain
across the warned area. Up to 0.5 inches of rain have fallen.
Additional rainfall amounts up to 0.5 inches are possible in the
warned area. Flash flooding is ongoing or expected to begin shortly.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Emergency management reported.
IMPACT...Life threatening flash flooding of creeks and streams,
roads, and low lying areas.
Some locations that will experience flash flooding include...
Glen Haven, Drake, Pennock Pass and Cedar Cove.
This includes the following additional locations...
Box Prairie, Upper Buckhorn along County Road 44H, Moondance Way,
Stringtown Gulch, Big Bear, Lower Buckhorn on County Road 27 above
Masonville, Crystal Mountain, The Retreat and Storm Mountain.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now. Act quickly to protect your life.
THIS IS A LIFE THREATENING SITUATION! Heavy Rainfall will cause
extensive and severe flooding of creeks, streams, roads and culverts
in the affected part of the Cameron Peak burn area. Rock slides or
debris flows can also be expected across roads in the warning area.
&&
LAT...LON 4059 10553 4058 10527 4041 10525 4042 10552
4057 10555
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
RPK791
WGUS75 KBOU 312149
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
349 PM MDT Sat Jul 31 2021
COC069-312159-
/O.EXP.KBOU.FF.W.0057.000000T0000Z-210731T2145Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
349 PM MDT Sat Jul 31 2021
...FLASH FLOOD WARNING HAS EXPIRED FOR SOUTH 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 900 PM MDT for Portions
of central, north central, and northeast Colorado.
LAT...LON 4059 10553 4058 10527 4041 10525 4042 10552
4057 10555
$$
RPKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 30, 6:01 PM MDT | Areal Flood Advisory | BOU | Boulder, Broomfield, Weld | 59 min |
| Jul 30, 6:08 PM MDT | Areal Flood Advisory | BOU | Adams, Denver | 82 min |
| Jul 30, 6:48 PM MDT | Areal Flood Advisory | BOU | Douglas, Elbert | 117 min |
| Jul 30, 7:13 PM MDT | Areal Flood Warning | BOU | Larimer | 3 hr |
| Jul 30, 7:35 PM MDT | Areal Flood Advisory | BOU | Boulder | 70 min |
| Jul 30, 7:52 PM MDT | Areal Flood Advisory | BOU | Boulder, Broomfield, Weld | 83 min |
| Jul 30, 7:53 PM MDT | Areal Flood Advisory | BOU | Larimer | 68 min |
| Jul 30, 8:19 PM MDT | Areal Flood Advisory | BOU | Douglas, Jefferson | 42 min |
| Jul 30, 9:34 PM MDT | Areal Flood Advisory | BOU | Adams, Boulder, Broomfield, Denver, Jefferson, Weld | 56 min |
| Jul 30, 9:35 PM MDT | Areal Flood Advisory | BOU | Clear Creek, Gilpin | 3 hr |
| Jul 30, 10:18 PM MDT | Flash Flood Warning | BOU | Boulder, Broomfield, Weld | 3 hr |
| Jul 30, 11:17 PM MDT | Special Weather Statement | BOU | Weld | 28 min |
| Jul 30, 11:24 PM MDT | Areal Flood Advisory | BOU | Weld | 81 min |
| Jul 30, 11:40 PM MDT | Areal Flood Advisory | BOU | Weld | 60 min |
| Jul 31, 1:12 AM MDT | Special Weather Statement | BOU | Logan | 33 min |
| Jul 31, 2:39 AM MDT | Special Weather Statement | BOU | Logan | 51 min |
| Jul 31, 3:20 AM MDT | Special Weather Statement | BOU | Phillips, Sedgwick | 40 min |
| Jul 31, 3:59 AM MDT | Areal Flood Advisory | BOU | Logan, Phillips, Sedgwick | 74 min |
| Jul 31, 11:49 AM MDT | Flash Flood Warning | BOU | Larimer | 2 hr |
| Jul 31, 12:27 PM MDT | Flash Flood Warning | BOU | Grand | 3 hr |
| Jul 31, 12:29 PM MDT | Areal Flood Advisory | BOU | Grand | 91 min |
| Jul 31, 12:32 PM MDT | Areal Flood Advisory | BOU | Grand | 88 min |
| Jul 31, 12:34 PM MDT | Areal Flood Advisory | BOU | Grand | 86 min |
| Jul 31, 12:39 PM MDT | Areal Flood Advisory | BOU | Park | 81 min |
| Jul 31, 12:42 PM MDT | Areal Flood Advisory | BOU | Park | 93 min |
| Jul 31, 1:05 PM MDT | Areal Flood Advisory | BOU | Larimer | 85 min |
| Jul 31, 1:33 PM MDT | Areal Flood Advisory | BOU | Grand | 87 min |
| Jul 31, 2:43 PM MDT | Flash Flood Warning | BOU | Larimer | 92 min |
| Jul 31, 2:57 PM MDT | Areal Flood Advisory | BOU | Park | 93 min |
| Jul 31, 3:24 PM MDT | Flash Flood Warning | BOU | Larimer | 81 min |
| Jul 31, 3:29 PM MDT | Areal Flood Advisory | BOU | Boulder | 91 min |
| Jul 31, 3:33 PM MDT | Flash Flood Warning | BOU | Park | 3 hr |
| Jul 31, 3:37 PM MDT | Flash Flood Warning | BOU | Boulder | 3 hr |
| Jul 31, 3:51 PM MDT | Areal Flood Advisory | BOU | Boulder | 84 min |
| Jul 31, 4:31 PM MDT | Areal Flood Advisory | BOU | Park | 89 min |
| Jul 31, 4:42 PM MDT | Areal Flood Advisory | BOU | Park | 93 min |
| Jul 31, 4:52 PM MDT | Areal Flood Advisory | BOU | Park | 83 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.