Alert archive / Colorado / Flash Flood Warnings in 2021

Flash Flood Warning 31, NWS Grand Junction, CO

July 25, 2021Gunnison County, Pitkin County, Colorado

NWS Grand Junction, CO issued this flash flood warning at Jul 25, 2021, 3:25 PM MDT for Gunnison County, Pitkin County, Colorado. It was in force for 3 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
Jul 25, 2021, 3:25 PM MDT (21:25 UTC)
Expired
Jul 25, 2021, 6:30 PM MDT
In force
3 hr
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Flood severity
None

Counties Gunnison County, CO, Pitkin County, CO

The radar

The Grand Junction radar (KGJX), 84 km from the middle of the area, began a volume at 21:24 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, 9.4 hours before the alert went out and 109 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 2021-07-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2021-07-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 6 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2095 m above ground
0-6 km bulk shear
3 kt
0-1 km storm-relative helicity
6 m²/s²
0-3 km storm-relative helicity
70 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

251 
WGUS55 KGJT 252125
FFWGJT
COC051-097-260030-
/O.NEW.KGJT.FF.W.0031.210725T2125Z-210726T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
325 PM MDT Sun Jul 25 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  Northwestern Gunnison County in west central Colorado...
  West Central Pitkin County in west central Colorado...

* Until 630 PM MDT.

* At 325 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 1 
  to 2 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...
  Highway 133 in between Redstone and McClure Pass as well as county 
  road 3 to Marble.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3922 10725 3920 10720 3916 10722 3912 10724
      3909 10720 3905 10721 3907 10728 3913 10731

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

KJS
2 follow-up statements
034 
WGUS75 KGJT 252208
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
408 PM MDT Sun Jul 25 2021

COC051-097-260030-
/O.CON.KGJT.FF.W.0031.000000T0000Z-210726T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Gunnison CO-Pitkin CO-
408 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM MDT THIS 
EVENING FOR NORTHWESTERN GUNNISON AND SOUTHWESTERN PITKIN COUNTIES...

At 408 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. The expected rainfall rate is 1 to 2 
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...
  McClure Pass and county road 3 to Marble.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3915 10730 3915 10726 3912 10724 3909 10720
      3905 10721 3907 10728 3913 10731

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 1 HOUR

$$

KJS
238 
WGUS75 KGJT 260031 RRA
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
631 PM MDT Sun Jul 25 2021

COC051-097-260041-
/O.EXP.KGJT.FF.W.0031.000000T0000Z-210726T0030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Gunnison CO-Pitkin CO-
631 PM MDT Sun Jul 25 2021

...FLASH FLOOD WARNING HAS EXPIRED FOR NORTHWESTERN GUNNISON AND 
SOUTHWESTERN PITKIN COUNTIES...

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

LAT...LON 3915 10730 3915 10726 3912 10724 3909 10720
      3905 10721 3907 10728 3913 10731

$$

NL

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 25, 1:02 PM MDTFlash Flood WatchGJTEagle, Garfield, Moffat, Pitkin, Rio Blanco, Routt7 hr
Jul 25, 1:38 PM MDTAreal Flood AdvisoryGJTDolores, San Miguel112 min
Jul 25, 3:53 PM MDTAreal Flood AdvisoryGJTRio Blanco2 hr
Jul 25, 4:06 PM MDTFlash Flood WarningGJTEagle3 hr
Jul 25, 4:45 PM MDTAreal Flood AdvisoryGJTMontezuma3 hr
Jul 25, 4:53 PM MDTSpecial Weather StatementGJTRio Blanco22 min
Jul 25, 4:54 PM MDTFlash Flood WarningGJTMontrose3 hr
Jul 25, 5:20 PM MDTSpecial Weather StatementGJTRio Blanco40 min
Jul 25, 5:46 PM MDTAreal Flood AdvisoryGJTRio Blanco3 hr

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.