Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 58, NWS Denver/Boulder, CO

July 31, 2021Larimer County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Jul 31, 2021, 2:43 PM MDT for Larimer County, Colorado. It was in force for 92 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, 2:43 PM MDT (20:43 UTC)
Expired: Jul 31, 2021, 4:15 PM MDT
In force: 92 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Flood severity: None

County Larimer County, CO

The radar

The Cheyenne radar (KCYS), 89 km from the middle of the area, began a volume at 20:46 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, 8.7 hours before the alert went out and 227 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

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

Open this sounding in Storm Lab

The text

As transmitted.

304 
WGUS55 KBOU 312043
FFWBOU
COC069-312215-
/O.NEW.KBOU.FF.W.0058.210731T2043Z-210731T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
243 PM MDT Sat Jul 31 2021

The National Weather Service in Denver has issued a

* Flash Flood Warning for...
  Central Larimer County in north central Colorado...

* Until 415 PM MDT.

* At 243 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 0.5 inches of rain have 
  fallen. Additional rainfall amounts up to 0.30 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...
  Rustic, Kinikinik, Pingree Park and Red Feather Lakes.

This includes the following additional locations...
Monument Gulch, Jacks Gulch, 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, 
Bellaire Lake, Crown Point Road and Remote areas in the Cameron Peak 
Wilderness.

This includes the following streams and drainages...
  Bennett Creek, Pennock Creek, Little Beaver Creek, Sheep Creek, 
  Cache La Poudre River, Laramie River, Manhattan Creek, Elkhorn 
  Creek, Dry Creek, Peterson Creek, Roaring Creek, Killpecker Creek, 
  South Fork Cache La Poudre River and South Lone Pine 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 4077 10579 4078 10547 4059 10551 4057 10559
      4062 10577 4076 10579

FLASH FLOOD...RADAR INDICATED

$$

RPK

The 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, 2:16 PM MDT	Flash Flood Warning	BOU	Larimer	89 min
Jul 31, 2:57 PM MDT	Areal Flood Advisory	BOU	Park	93 min
Jul 31, 3:24 PM MDT	Flash Flood Warning Considerable damage threat	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, 2021 Every 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.