Alert archive / Colorado / Flash Flood Warnings in 2021
Flash Flood Warning 74, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this flash flood warning at Aug 16, 2021, 4:32 PM MDT for Larimer County, Colorado. It was in force for 118 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
- Aug 16, 2021, 4:32 PM MDT (22:32 UTC)
- Expired
- Aug 16, 2021, 6:30 PM MDT
- In force
- 118 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Flood severity
- None
County Larimer County, CO
The radar
The Cheyenne radar (KCYS), 104 km from the middle of the area, began a volume at 22:35 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, 10.5 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
- 1 J/kg
- Mixed-layer CIN
- -425 J/kg
- Mixed-layer LCL
- 2615 m above ground
- 0-6 km bulk shear
- 13 kt
- 0-1 km storm-relative helicity
- 28 m²/s²
- 0-3 km storm-relative helicity
- 38 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
109
WGUS55 KBOU 162232
FFWBOU
COC069-170030-
/O.NEW.KBOU.FF.W.0074.210816T2232Z-210817T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
432 PM MDT Mon Aug 16 2021
The National Weather Service in Denver has issued a
* Flash Flood Warning for...
Central Larimer County in north central Colorado...
* Until 630 PM MDT.
* At 432 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...
Chambers Lake.
This includes the following additional locations...
The Upper Poudre Canyon and The Laramie River Road near Chambers
Lake.
This includes the following streams and drainages...
Two and One Half Creek, Joe Wright Creek, Cache La Poudre River,
Laramie River and North Fork West Branch Laramie River.
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 4068 10588 4069 10582 4063 10577 4060 10578
4058 10586 4064 10586 4064 10590
FLASH FLOOD...RADAR INDICATED
$$
RPK1 follow-up statement
632
WGUS75 KBOU 170023
FFSBOU
Flash Flood Statement
National Weather Service Denver CO
623 PM MDT Mon Aug 16 2021
COC069-170033-
/O.EXP.KBOU.FF.W.0074.000000T0000Z-210817T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Larimer CO-
623 PM MDT Mon Aug 16 2021
...FLASH FLOOD WARNING WILL EXPIRE AT 630 PM MDT THIS EVENING FOR
CENTRAL LARIMER COUNTY...
The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.
LAT...LON 4068 10588 4069 10582 4063 10577 4060 10578
4058 10586 4064 10586 4064 10590
$$
RPKThe office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 15, 6:16 PM MDT | Special Weather Statement | BOU | Lincoln | 59 min |
| Aug 16, 3:53 PM MDT | Flash Flood Warning | BOU | Jackson, Larimer | 112 min |
| Aug 16, 4:06 PM MDT | Areal Flood Advisory | BOU | Grand | 18 min |
| Aug 16, 4:24 PM MDT | Flash Flood Warning | BOU | Grand | 111 min |
| Aug 16, 5:02 PM MDT | Areal Flood Advisory | BOU | Grand | 88 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.