Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 80, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Aug 20, 2021, 2:15 AM MDT for Larimer County, Colorado. It was in force for 2 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 20, 2021, 2:15 AM MDT (08:15 UTC)
- Expired
- Aug 20, 2021, 4:35 AM MDT
- In force
- 2 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 08:16 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 00:00Z, 8.3 hours before the alert went out and 188 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
- 56 J/kg
- Mixed-layer CIN
- -210 J/kg
- Mixed-layer LCL
- 1497 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 52 m²/s²
- 0-3 km storm-relative helicity
- 222 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted.
990
WGUS55 KBOU 200815
FFWBOU
COC069-201115-
/O.NEW.KBOU.FF.W.0080.210820T0815Z-210820T1115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
215 AM MDT Fri Aug 20 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
East Central Larimer County in north central Colorado...
* Until 515 AM MDT.
* At 215 AM MDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.3 and 0.5 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...
Masonville.
This includes the following additional locations...
Moondance Way, Stringtown Gulch and Big Bear.
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 4054 10532 4056 10527 4054 10521 4048 10518
4044 10523 4045 10533 4050 10534
FLASH FLOOD...RADAR INDICATED
$$
Danielson1 follow-up statement
720
WGUS75 KBOU 201035
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
435 AM MDT Fri Aug 20 2021
COC069-201045-
/O.CAN.KBOU.FF.W.0080.000000T0000Z-210820T1115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
435 AM MDT Fri Aug 20 2021
...FLASH FLOOD WARNING IS CANCELLED FOR EAST CENTRAL LARIMER
COUNTY...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
LAT...LON 4054 10532 4056 10527 4054 10521 4048 10518
4044 10523 4045 10533 4050 10534
$$
DanielsonThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 6:21 PM MDT | Severe Thunderstorm Warning | BOU | Phillips | 24 min |
| Aug 19, 6:41 PM MDT | Severe Thunderstorm Warning | BOU | Phillips | 49 min |
| Aug 19, 6:43 PM MDT | Areal Flood Advisory | BOU | Phillips | 2 hr |
| Aug 19, 7:43 PM MDT | Flash Flood Warning | BOU | Phillips | 3 hr |
| Aug 19, 10:38 PM MDT | Flash Flood Warning | BOU | Phillips | 4 hr |
| Aug 20, 2:12 AM MDT | Areal Flood Advisory | BOU | Larimer | 93 min |
| Aug 20, 2:58 AM MDT | Areal Flood Warning | BOU | Phillips | 9 hr |
| Aug 20, 4:01 AM MDT | Special Weather Statement | BOU | Morgan | 44 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.