Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 76, NWS Grand Junction, CO

August 3, 2021Eagle County, Garfield County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Aug 3, 2021, 2:54 PM MDT for Eagle County, Garfield County, Colorado. It was in force for 111 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 3, 2021, 2:54 PM MDT (20:54 UTC)
Expired
Aug 3, 2021, 4:45 PM MDT
In force
111 min
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Eagle County, CO, Garfield County, CO

The radar

The Grand Junction radar (KGJX), 107 km from the middle of the area, began a volume at 20:53 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

Grand Junction, CO (KGJT), launched 12:00Z, 8.9 hours before the alert went out and 125 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-pSkew-T log-p diagram, Grand Junction, CO at 12:00Z on 2021-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Grand Junction, CO at 12:00Z on 2021-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
5 J/kg
Mixed-layer CIN
-176 J/kg
Mixed-layer LCL
1792 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
48 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

648 
WGUS55 KGJT 032054
FFWGJT
COC037-045-032245-
/O.NEW.KGJT.FF.W.0076.210803T2054Z-210803T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
254 PM MDT Tue Aug 3 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  The Grizzly Creek Fire Burn Area Deadhorse and French Creek 
  drainages in...
  Western Eagle County in west central Colorado...
  East Central Garfield County in west central Colorado...

* Until 445 PM MDT.

* At 254 PM MDT, Doppler radar indicated thunderstorms producing 
  moderate to heavy rain over the Grizzly Creek Fire Burn Area 
  Deadhorse and French Creek drainages. Between 0.2 and 0.5 inches 
  of rain have fallen. The expected rainfall rate is 0.3 to 0.7 
  inches in 1 hour. Flash flooding is ongoing or expected to begin 
  shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Grizzly Creek burn scar along the Deadhorse and 
French Creek drainages. The debris flow can consist of rock, mud, 
vegetation and other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding in and around the Grizzly
           Creek Fire Burn Area Deadhorse and French Creek
           drainages.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of areas in and around
           the Grizzly Creek Fire Burn Area Deadhorse and French
           Creek drainages.

* Some locations that will experience flash flooding include...
  Glenwood Springs and Shoshone.

This includes the following highways...
	Interstate 70 in Colorado between mile markers 118 and 129.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Grizzly Creek Fire Burn Area including Deadhorse and 
French Creek drainages. Severe debris flows can also be anticipated 
across roads. Roads and driveways may be washed away in places. If 
you encounter flood waters...climb to safety.

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

&&

LAT...LON 3965 10722 3967 10720 3965 10713 3962 10712
      3961 10714 3960 10711 3958 10708 3957 10711
      3955 10714 3954 10720 3954 10724 3956 10731
      3963 10729 3963 10726 3964 10725

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.3-0.7 INCHES IN 1 HOUR

$$

15
2 follow-up statements
601 
WGUS75 KGJT 032149
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
349 PM MDT Tue Aug 3 2021

COC037-045-032245-
/O.CON.KGJT.FF.W.0076.000000T0000Z-210803T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Eagle CO-Garfield CO-
349 PM MDT Tue Aug 3 2021

...FLASH FLOOD WARNING FOR THE GRIZZLY CREEK FIRE BURN AREA 
INCLUDING DEADHORSE AND FRENCH CREEK DRAINAGES REMAINS IN EFFECT 
UNTIL 445 PM MDT THIS AFTERNOON FOR WESTERN EAGLE AND EAST CENTRAL 
GARFIELD COUNTIES...

At 349 PM MDT, Doppler radar and automated rain gauges indicated 
thunderstorms producing heavy rain over the Grizzly Creek Fire Burn 
Area including Deadhorse and French Creek drainages. Between 0.4 and 
0.6 inches of rain have fallen. The expected rainfall rate is 0.3 to 
0.7 inches in 1 hour. Flash flooding is ongoing or expected to begin 
shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Grizzly Creek burn scar mainly in the Deadhorse 
and French Creek drainages. The debris flow can consist of rock, 
mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Grizzly Creek Fire Burn
         Area Deadhorse and French Creek drainages.

SOURCE...Radar and automated gauges.

IMPACT...Life threatening flash flooding of areas in and around
         the Grizzly Creek Fire Burn Area in the Deadhorse and
         French Creek drainages.

Some locations that will experience flash flooding include...
  eastern end of the Grizzly Creek burn scar. 

This includes the following highways...
	Interstate 70 in Colorado between mile markers 123 and 129.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause 
extensive and severe flash flooding of creeks...streams...and 
ditches in the Grizzly Creek Fire Burn Area including Deadhorse and 
French Creek drainages. Severe debris flows can also be anticipated 
across roads. Roads and driveways may be washed away in places. If 
you encounter flood waters...climb to safety.

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

&&

LAT...LON 3965 10722 3967 10720 3965 10713 3962 10712
      3961 10714 3960 10711 3958 10708 3957 10711
      3955 10714 3954 10720 3954 10724 3956 10731
      3963 10729 3963 10726 3964 10725

FLASH FLOOD...RADAR AND GAUGE INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...0.3-0.7 INCHES IN 1 HOUR

$$

15
222 
WGUS75 KGJT 032242
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
442 PM MDT Tue Aug 3 2021

COC037-045-032252-
/O.EXP.KGJT.FF.W.0076.000000T0000Z-210803T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Eagle CO-Garfield CO-
442 PM MDT Tue Aug 3 2021

...FLASH FLOOD WARNING FOR THE GRIZZLY CREEK FIRE BURN AREA WILL 
EXPIRE AT 445 PM MDT THIS AFTERNOON FOR WESTERN EAGLE AND EAST 
CENTRAL GARFIELD COUNTIES...

The heavy rain has ended...however light rainfall will continue over 
the burn scar over the next half hour and some water may continue to 
runoff over the next few hours.

A Flash Flood Watch remains in effect until 1200 AM MDT Wednesday. 

LAT...LON 3965 10722 3967 10720 3965 10713 3962 10712
      3961 10714 3960 10711 3958 10708 3957 10711
      3955 10714 3954 10720 3954 10724 3956 10731
      3963 10729 3963 10726 3964 10725

$$

15

The office that day

Everything else NWS Grand Junction, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 2, 6:41 PM MDTSpecial Weather StatementGJT49 min
Aug 2, 7:44 PM MDTAreal Flood AdvisoryGJTGarfield, Mesa2 hr
Aug 2, 8:21 PM MDTAreal Flood AdvisoryGJTMesa114 min
Aug 2, 8:27 PM MDTFlash Flood Warning Considerable damage threatGJTEagle, Garfield2 hr
Aug 2, 8:43 PM MDTFlash Flood Warning Considerable damage threatGJTGarfield, Mesa2 hr
Aug 3, 9:32 AM MDTAreal Flood AdvisoryGJTEagle3 hr
Aug 3, 12:16 PM MDTFlash Flood Warning Considerable damage threatGJTSan Miguel88 min
Aug 3, 3:21 PM MDTFlash Flood WarningGJTSan Miguel104 min
Aug 3, 3:27 PM MDTFlash Flood Warning Considerable damage threatGJTEagle, Garfield, Pitkin2 hr
Aug 3, 4:04 PM MDTSpecial Weather StatementGJTSan Miguel41 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.