Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 4, NWS Denver/Boulder, CO

June 5, 2021Grand County, Colorado

NWS Denver/Boulder, CO issued this flash flood warning at Jun 5, 2021, 1:59 PM MDT for Grand County, Colorado. It was in force for 78 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: Jun 5, 2021, 1:59 PM MDT (19:59 UTC)
Expired: Jun 5, 2021, 3:17 PM MDT
In force: 78 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Flood severity: None

County Grand County, CO

The radar

The Denver radar (KFTG), 126 km from the middle of the area, began a volume at 19:59 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, 8.0 hours before the alert went out and 228 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 3372 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 51 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

666 
WGUS55 KBOU 051959
FFWBOU
COC049-052200-
/O.NEW.KBOU.FF.W.0004.210605T1959Z-210605T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Denver CO
159 PM MDT Sat Jun 5 2021

The National Weather Service in Denver has issued a

* Flash Flood Warning for...
  Northeastern Grand County in north central Colorado...

* Until 400 PM MDT.

* At 159 PM MDT, Doppler radar indicated thunderstorms producing 
  moderate to heavy rain across the warned area. The expected 
  rainfall rate is 0.75 inches in 1 hour. 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, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Grand Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy Rainfall will cause minor flooding of small creeks, streams, 
and ditches in the East Troublesome burn area. Some areas affected 
include the North Inlet in the town of Grand Lake, the burned areas 
on the west side of Rocky Mountain National Park, the Colorado River 
above Shadow Mountain Reservoir, the Willow Creek valley along 
Highway 125, Drowsy Water Creek, and the East Troublesome Creek 
valley. The heavy rains could also trigger rock slides or debris 
flows.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4033 10571 4026 10572 4023 10584 4015 10590
      4018 10593 4026 10599 4035 10599 4035 10597
      4035 10596 4036 10595 4037 10594 4039 10586
      4036 10577 4035 10576 4035 10574 4033 10573

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.75 INCHES IN 1 HOUR

$$

RJK

2 follow-up statements

527 
WGUS75 KBOU 052049
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
249 PM MDT Sat Jun 5 2021

COC049-052200-
/O.CON.KBOU.FF.W.0004.000000T0000Z-210605T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
249 PM MDT Sat Jun 5 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM MDT THIS 
AFTERNOON FOR NORTHEASTERN GRAND COUNTY...

At 249 PM MDT, Doppler radar indicated thunderstorms producing light 
to moderate heavy rain across the warned area. Between 0.3 and 0.5 
inches of rain have fallen. The expected rainfall rate is 0.25 
inches in 1 hour. 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, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Grand Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy Rainfall will cause minor flooding of small creeks, streams, 
and ditches in the East Troublesome burn area. Some areas affected 
include the North Inlet in the town of Grand Lake, the burned areas 
on the west side of Rocky Mountain National Park, the Colorado River 
above Shadow Mountain Reservoir, the Willow Creek valley along 
Highway 125, Drowsy Water Creek, and the East Troublesome Creek 
valley. The heavy rains could also trigger rock slides or debris 
flows.

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4033 10571 4026 10572 4023 10584 4015 10590
      4018 10593 4026 10599 4035 10599 4035 10597
      4035 10596 4036 10595 4037 10594 4039 10586
      4036 10577 4035 10576 4035 10574 4033 10573

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.25 INCHES IN 1 HOUR

$$

RJK

690 
WGUS75 KBOU 052117
FFSBOU

Flash Flood Statement
National Weather Service Denver CO
317 PM MDT Sat Jun 5 2021

COC049-052127-
/O.CAN.KBOU.FF.W.0004.000000T0000Z-210605T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand CO-
317 PM MDT Sat Jun 5 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHEASTERN GRAND COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4033 10571 4026 10572 4023 10584 4015 10590
      4018 10593 4026 10599 4035 10599 4035 10597
      4035 10596 4036 10595 4037 10594 4039 10586
      4036 10577 4035 10576 4035 10574 4033 10573

$$

RJK

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 5, 12:28 PM MDT	Flash Flood Warning	BOU	Larimer	98 min
Jun 5, 1:29 PM MDT	Areal Flood Advisory	BOU	Grand	109 min
Jun 5, 2:43 PM MDT	Areal Flood Advisory	BOU	Grand	2 hr

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.