Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 82, NWS Grand Junction, CO

August 26, 2021Grand County, San Juan County, Utah

NWS Grand Junction, CO issued this flash flood warning at Aug 26, 2021, 5:42 PM MDT for Grand County, San Juan County, Utah. 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
Aug 26, 2021, 5:42 PM MDT (23:42 UTC)
Expired
Aug 26, 2021, 8:30 PM MDT
In force
3 hr
Issued by
NWS Grand Junction, CO
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Grand County, UT, San Juan County, UT

The radar

The Grand Junction radar (KGJX), 119 km from the middle of the area, began a volume at 23:44 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, 11.7 hours before the alert went out and 104 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 2021-08-26Temperature 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 2021-08-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -78 square meters per square second.19395878Sfc1 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
3119 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
-78 m²/s²
0-3 km storm-relative helicity
-14 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

032 
WGUS55 KGJT 262342
FFWGJT
UTC019-037-270230-
/O.NEW.KGJT.FF.W.0082.210826T2342Z-210827T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Grand Junction CO
542 PM MDT Thu Aug 26 2021

The National Weather Service in Grand Junction has issued a

* Flash Flood Warning for...
  Southeastern Grand County in east central Utah...
  Northeastern San Juan County in southeastern Utah...

* Until 830 PM MDT.

* At 542 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain approaching the Pack Creek Burn Area. Additional 
  rainfall amounts of 0.5 to 1 inch are possible over the warned 
  area. Flash flooding is ongoing or expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Pack Creek drainage area and areas downstream. 
The debris flow can consist of rock, mud, vegetation and other loose 
materials.

  HAZARD...Flash flooding caused by thunderstorms in and around
           the Pack Creek Fire Burn Area.

  SOURCE...Radar.

  IMPACT...Flooding of areas in and around the Pack Creek Fire
           Burn Area.

* Some locations that will experience flash flooding include...
  Pack Creek drainage down to U.S. Highway 191 in Utah between mile 
  markers 117 and 120, and potentially down through Spanish Valley.

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 Pack Creek Fire Burn Area. 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.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3855 10952 3856 10951 3851 10946 3847 10944
      3845 10937 3847 10933 3848 10930 3851 10926
      3850 10922 3844 10923 3844 10926 3845 10928
      3842 10933 3843 10939 3847 10945

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

erin.walter
2 follow-up statements
467 
WGUS75 KGJT 270101
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
701 PM MDT Thu Aug 26 2021

UTC019-037-270230-
/O.CON.KGJT.FF.W.0082.000000T0000Z-210827T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand UT-San Juan UT-
701 PM MDT Thu Aug 26 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 830 PM MDT THIS 
EVENING FOR SOUTHEASTERN GRAND AND NORTHEASTERN SAN JUAN COUNTIES...

At 701 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain approaching the Pack Creek Burn Area. Additional rainfall 
amounts of 0.5 to 1 inch are possible over the warned area. Flash 
flooding is ongoing or expected to begin shortly.

Excessive rainfall over the burn scar may result in debris flow 
moving through the Pack Creek drainage area and areas downstream. 
The debris flow can consist of rock, mud, vegetation and other loose 
materials.

HAZARD...Flash flooding caused by thunderstorms in and around the
         Pack Creek Fire Burn Area.

SOURCE...Radar.

IMPACT...Flooding of areas in and around the Pack Creek Fire Burn
         Area.

Some locations that will experience flash flooding include...
  Pack Creek drainage down to U.S. Highway 191 in Utah between mile 
  markers 117 and 120, and potentially down through Spanish Valley.

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 Pack Creek Fire Burn Area. 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.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3855 10952 3856 10951 3851 10946 3847 10944
      3845 10937 3847 10933 3848 10930 3851 10926
      3850 10922 3844 10923 3844 10926 3845 10928
      3842 10933 3843 10939 3847 10945

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

erin.walter
616 
WGUS75 KGJT 270224
FFSGJT

Flash Flood Statement
National Weather Service Grand Junction CO
824 PM MDT Thu Aug 26 2021

UTC019-037-270234-
/O.EXP.KGJT.FF.W.0082.000000T0000Z-210827T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Grand UT-San Juan UT-
824 PM MDT Thu Aug 26 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 830 PM MDT THIS EVENING FOR 
SOUTHEASTERN GRAND AND NORTHEASTERN SAN JUAN COUNTIES...

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

LAT...LON 3855 10952 3856 10951 3851 10946 3847 10944
      3845 10937 3847 10933 3848 10930 3851 10926
      3850 10922 3844 10923 3844 10926 3845 10928
      3842 10933 3843 10939 3847 10945

$$

erin.walter

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 26, 2:42 PM MDTSpecial Weather StatementGJTUintah33 min
Aug 26, 4:28 PM MDTSevere Thunderstorm WarningGJTGrand, San Juan32 min
Aug 26, 4:42 PM MDTSpecial Weather StatementGJTUintah33 min
Aug 26, 4:52 PM MDTFlash Flood WarningGJTSan Juan3 hr
Aug 26, 5:02 PM MDTSevere Thunderstorm WarningGJTGrand, San Juan28 min

Nearby

Flash Flood Warnings in Utah, 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.