Alert archive / Utah / Flash Flood Warnings in 2021

Flash Flood Warning 71, NWS Salt Lake City, UT

July 31, 2021Duchesne County, Wasatch County, Utah

NWS Salt Lake City, UT issued this flash flood warning at Jul 31, 2021, 1:23 PM MDT for Duchesne County, Wasatch 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, 1:23 PM MDT (19:23 UTC)
Expired: Jul 31, 2021, 4:15 PM MDT
In force: 3 hr
Issued by: NWS Salt Lake City, UT
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

Counties Duchesne County, UT, Wasatch County, UT

The radar

The Salt Lake City radar (KMTX), 189 km from the middle of the area, began a volume at 19:23 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, 7.4 hours before the alert went out and 120 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: 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.

273 
WGUS55 KSLC 311923
FFWSLC
UTC013-051-312215-
/O.NEW.KSLC.FF.W.0071.210731T1923Z-210731T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Salt Lake City UT
123 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...
  West Central Duchesne County in northern Utah...
  Southeastern Wasatch County in northern Utah...

* Until 415 PM MDT.

* At 123 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain over the Dollar Ridge Burn Scar. Between 0.3 and 0.6 
  inches of rain have fallen over the last 30 minutes. The expected 
  rainfall rate is 1 to 1.5 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 Strawberry River to its terminus at the 
Starvation Reservoir. 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 Dollar
           Ridge Burn Scar.

  SOURCE...Radar.

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

* Some locations that will experience flash flooding include...
  Promised Land Resort.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry washes is likely. The heavy rains 
will likely trigger rockslides, mudslides and debris flows in steep 
terrain, especially in and around these areas.

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

&&

LAT...LON 4017 11090 4015 11075 4015 11063 4017 11059
      4017 11053 4016 11052 4012 11063 4009 11079
      4007 11082 4003 11097 4012 11105 4018 11092

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-1.5 INCHES IN 1 HOUR

$$

GM

2 follow-up statements

607 
WGUS75 KSLC 312053
FFSSLC

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

UTC013-051-312215-
/O.CON.KSLC.FF.W.0071.000000T0000Z-210731T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Duchesne UT-Wasatch UT-
253 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING FOR THE DOLLAR RIDGE BURN SCAR REMAINS IN 
EFFECT UNTIL 415 PM MDT THIS AFTERNOON FOR WEST CENTRAL DUCHESNE AND 
SOUTHEASTERN WASATCH COUNTIES...

At 253 PM MDT, Doppler radar indicates earlier thunderstorms 
produced between .60 to 1.25 inches of heavy rain over central 
portions of the the Dollar Ridge Burn Scar. Flash flooding is 
ongoing or expected to begin shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Strawberry River to its terminus at the 
Starvation Reservoir. 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 Dollar Ridge Burn Scar.

SOURCE...Radar.

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

Some locations that will experience flash flooding include...
  The Promised Land Resort.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry washes is likely. The heavy rains 
will likely trigger rockslides, mudslides and debris flows in steep 
terrain, especially in and around these areas.

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

&&

LAT...LON 4017 11090 4015 11075 4015 11063 4017 11059
      4017 11053 4016 11052 4012 11063 4009 11079
      4007 11082 4003 11097 4012 11105 4018 11092

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

$$

GM

989 
WGUS75 KSLC 312224
FFSSLC

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

UTC051-312234-
/O.EXP.KSLC.FF.W.0071.000000T0000Z-210731T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Wasatch UT-
424 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING FOR THE DOLLAR RIDGE BURN SCAR HAS EXPIRED 
FOR WEST CENTRAL DUCHESNE AND SOUTHEASTERN WASATCH COUNTIES...

A debris flow has moved off the Dollar Ridge burn scar is currently 
moving through the Pinnacles and Promised Land Resort along the 
Strawberry River. This Flash Flood Warning has been replaced with an 
additional Flash Flood Warning which is valid through 715 PM MDT 
this evening as this debris flow continues to move downstream along 
the Strawberry River to its terminus at Starvation Reservoir.

LAT...LON 4017 11090 4015 11075 4015 11063 4017 11059
      4017 11053 4016 11052 4012 11063 4009 11079
      4007 11082 4003 11097 4012 11105 4018 11092

$$

GM

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 30, 7:17 PM MDT	Special Weather Statement	SLC	Beaver	43 min
Jul 30, 7:31 PM MDT	Special Weather Statement	SLC		44 min
Jul 31, 12:31 PM MDT	Special Weather Statement	SLC	Summit	44 min
Jul 31, 1:12 PM MDT	Special Weather Statement	SLC	Iron	33 min
Jul 31, 1:30 PM MDT	Severe Thunderstorm Warning	SLC	Iron, Washington	30 min
Jul 31, 1:39 PM MDT	Special Weather Statement	SLC	Morgan	36 min
Jul 31, 2:10 PM MDT	Special Weather Statement	SLC	Morgan	50 min
Jul 31, 2:38 PM MDT	Special Weather Statement	SLC	Morgan	37 min
Jul 31, 2:47 PM MDT	Severe Thunderstorm Warning	SLC	Morgan, Rich, Summit	28 min
Jul 31, 2:52 PM MDT	Special Weather Statement	SLC	Rich	23 min
Jul 31, 3:00 PM MDT	Areal Flood Advisory	SLC	Iron	107 min
Jul 31, 3:10 PM MDT	Special Weather Statement	SLC	Morgan	20 min
Jul 31, 3:16 PM MDT	Severe Thunderstorm Warning	SLC	Box Elder, Cache, Weber	29 min
Jul 31, 3:35 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Iron	3 hr
Jul 31, 3:41 PM MDT	Special Weather Statement	SLC	Cache	19 min
Jul 31, 4:00 PM MDT	Severe Thunderstorm Warning	SLC	Iron	30 min
Jul 31, 4:06 PM MDT	Special Weather Statement	SLC	Beaver	24 min
Jul 31, 4:10 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Utah	3 hr
Jul 31, 4:19 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Duchesne	3 hr
Jul 31, 4:39 PM MDT	Special Weather Statement	SLC	Rich	66 min
Jul 31, 5:01 PM MDT	Special Weather Statement	SLC		29 min
Jul 31, 5:11 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Washington	3 hr
Jul 31, 5:25 PM MDT	Special Weather Statement	SLC	Juab	35 min
Jul 31, 5:37 PM MDT	Special Weather Statement	SLC	Washington	38 min
Jul 31, 5:39 PM MDT	Flash Flood Warning Considerable damage threat	SLC	Kane, Washington	5 hr

Nearby

Flash Flood Warnings in Utah, 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.