Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 74, NWS Salt Lake City, UT

July 31, 2021Duchesne County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 31, 2021, 4:19 PM MDT for Duchesne 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
Jul 31, 2021, 4:19 PM MDT (22:19 UTC)
Expired
Jul 31, 2021, 7:15 PM MDT
In force
3 hr
Issued by
NWS Salt Lake City, UT
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County Duchesne County, UT

The radar

The Salt Lake City radar (KMTX), 196 km from the middle of the area, began a volume at 22:19 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

Salt Lake City I, UT (KSLC), launched 12:00Z, 10.3 hours before the alert went out and 127 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, Salt Lake City I, UT at 12:00Z on 2021-07-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 149 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, Salt Lake City I, UT at 12:00Z on 2021-07-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 44 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
149 J/kg
Mixed-layer CIN
-128 J/kg
Mixed-layer LCL
1716 m above ground
0-6 km bulk shear
5 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
76 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

438 
WGUS55 KSLC 312219
FFWSLC
UTC013-010115-
/O.NEW.KSLC.FF.W.0074.210731T2219Z-210801T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
419 PM MDT Sat Jul 31 2021

The National Weather Service in Salt Lake City has issued a

* Flash Flood Warning for...
  The Dollar Ridge burn scar in...
  Southwestern Duchesne County in northern Utah...

* Until 715 PM MDT.

* At 419 PM MDT, local law enforcement reported a debris flow moving 
  through Pinnacles area and within the Promised Land Resort area. 
  Flash flooding is ongoing.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Pinnacles area, Promised Land Resort, then 
downstream the Strawberry River to its terminus at Starvation 
Reservoir. The debris flow can consist of rock, mud, vegetation and 
other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding downstream of the Dollar
           Ridge Burn Scar along the Strawberry River to its
           terminus at Starvation River.

  SOURCE...Law enforcement reported.

  IMPACT...Life threatening flash flooding of areas in and around
           the Dollar Ridge Burn Scar.

* Some locations that will experience flash flooding include...
  Pinnacles, Promised Land Resort, and points downstream on the 
  Strawberry River to Starvation Reservoir.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

Flooding is occurring or is imminent. It is important to know where 
you are relative to streams, rivers, or creeks which can become 
killers in heavy rains. Campers and hikers should avoid streams or 
creeks.

&&

LAT...LON 4014 11077 4014 11065 4016 11059 4017 11053
      4014 11057 4013 11061 4012 11069 4010 11077

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

GM
1 follow-up statement
899 
WGUS75 KSLC 010112
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
712 PM MDT Sat Jul 31 2021

UTC013-010122-
/O.EXP.KSLC.FF.W.0074.000000T0000Z-210801T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Duchesne UT-
712 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING FOR THE DOLLAR RIDGE BURN SCAR WILL EXPIRE AT 
715 PM MDT THIS EVENING FOR SOUTHWESTERN DUCHESNE COUNTY...

The heavy rain has ended. Please continue to heed any road closures 
and or clean up efforts taking place after the earlier debris flow.

LAT...LON 4014 11077 4014 11065 4016 11059 4017 11053
      4014 11057 4013 11061 4012 11069 4010 11077

$$

GM

The office that day

Everything else NWS Salt Lake City, UT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 30, 7:17 PM MDTSpecial Weather StatementSLCBeaver43 min
Jul 30, 7:31 PM MDTSpecial Weather StatementSLC44 min
Jul 31, 12:31 PM MDTSpecial Weather StatementSLCSummit44 min
Jul 31, 1:12 PM MDTSpecial Weather StatementSLCIron33 min
Jul 31, 1:23 PM MDTFlash Flood Warning Considerable damage threatSLCDuchesne, Wasatch3 hr
Jul 31, 1:30 PM MDTSevere Thunderstorm WarningSLCIron, Washington30 min
Jul 31, 1:39 PM MDTSpecial Weather StatementSLCMorgan36 min
Jul 31, 2:10 PM MDTSpecial Weather StatementSLCMorgan50 min
Jul 31, 2:38 PM MDTSpecial Weather StatementSLCMorgan37 min
Jul 31, 2:47 PM MDTSevere Thunderstorm WarningSLCMorgan, Rich, Summit28 min
Jul 31, 2:52 PM MDTSpecial Weather StatementSLCRich23 min
Jul 31, 3:00 PM MDTAreal Flood AdvisorySLCIron107 min
Jul 31, 3:10 PM MDTSpecial Weather StatementSLCMorgan20 min
Jul 31, 3:16 PM MDTSevere Thunderstorm WarningSLCBox Elder, Cache, Weber29 min
Jul 31, 3:35 PM MDTFlash Flood Warning Considerable damage threatSLCIron3 hr
Jul 31, 3:41 PM MDTSpecial Weather StatementSLCCache19 min
Jul 31, 4:00 PM MDTSevere Thunderstorm WarningSLCIron30 min
Jul 31, 4:06 PM MDTSpecial Weather StatementSLCBeaver24 min
Jul 31, 4:10 PM MDTFlash Flood Warning Considerable damage threatSLCUtah3 hr
Jul 31, 4:39 PM MDTSpecial Weather StatementSLCRich66 min
Jul 31, 5:01 PM MDTSpecial Weather StatementSLC29 min
Jul 31, 5:11 PM MDTFlash Flood Warning Considerable damage threatSLCWashington3 hr
Jul 31, 5:25 PM MDTSpecial Weather StatementSLCJuab35 min
Jul 31, 5:37 PM MDTSpecial Weather StatementSLCWashington38 min
Jul 31, 5:39 PM MDTFlash Flood Warning Considerable damage threatSLCKane, Washington5 hr

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.